Professional Traffic Operations Engineer

Certification Program Refresher Course

Student Supplement

Module 4
Traffic Control Devices

© 2022 - Institute of Transportation Engineers

1627 Eye Street, NW, Suite 550 | Washington, DC 20006
Introduction to Refresher Course
This Refresher Course provides an overview of topics, key references and independent study materials by
topic for practicing engineers who intend to take the PTOE certification examination. The suite of modules
includes six (6) webinar recordings on traffic operations analysis, operational effects of geometric designs,
traffic safety, traffic control devices, traffic engineering studies, and social, environmental, and
institutional issues, each accompanied by a student supplement.
This 2022 version of the course and student supplement is an update and expansion to a July 2016 course
managed by Robert K. Seyfried, P.E., PTOE. Contributors to that course were:
• Robert K. Seyfried, P.E., PTOE; President, R. K. Seyfried and Associates, Inc.; Evanston, IL
• Jerome Hall, Ph.D., P.E., Professor Emeritus, Civil Engineering, University of New Mexico,
Albuquerque, NM
• Pat Noyes, Principal, Pat Noyes and Associates, Boulder, CO
• Eric T. Donnell, Ph.D., P.E., Assistant Professor, Department of Civil and Environmental
Engineering, The Pennsylvania State University, State College, PA
• John M. Mason, Jr., Ph.D., P.E., Associate Dean of Graduate Studies, Research, and Outreach and
Professor of Civil Engineering, The Pennsylvania State University, State College, PA
• Martin E. Lipinski, Ph.D., P.E., PTOE, Professor, Department of Civil Engineering, University of
Memphis; Memphis, TN
This 2022 version was updated by:
• Peter J. Yauch, P.E., PTOE, RSP2i, Vice President, Iteris, Inc., Tampa, FL

Much appreciation is given to Stephen J. Manhart, P.E., PTOE, PTP, RSP1, Project Manager for Traffic
Engineering, Michael Baker International, Minneapolis, MN, for his review of the student supplements on
behalf of the Transportation Professional Certification Board.

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Contents
Fundamentals of Traffic Control Devices ...................................................................................................... 1
Manual on Uniform Traffic Control Devices ................................................................................................. 2
Signing ........................................................................................................................................................... 4
Dimensions................................................................................................................................................ 4
Retroreflectivity ........................................................................................................................................ 6
Message Clarity ......................................................................................................................................... 5
Regulatory, Warning, And Guide Signs ..................................................................................................... 6
Regulatory Signs .................................................................................................................................... 7
Warning Signs ....................................................................................................................................... 8
Guide Signs ............................................................................................................................................ 9
Motorist Information Signs ................................................................................................................... 9
Changeable Message Signs ................................................................................................................. 10
Highway Fonts ........................................................................................................................................... 5
Color .......................................................................................................................................................... 6
Location And Spacing ................................................................................................................................ 5
Transit, Bicycle, And Pedestrian Considerations..................................................................................... 10
Sign Supports .......................................................................................................................................... 10
Maintenance Of Traffic Control Signs ..................................................................................................... 10
Maintaining Adequate Retroreflectivity ............................................................................................. 11
Traffic Signals .............................................................................................................................................. 13
Signal Warrant Studies ............................................................................................................................ 13
Detection................................................................................................................................................. 14
Signal Displays ......................................................................................................................................... 14
Phasing And Timing (e.g., Clearance Intervals, Preemption) .................................................................. 15
Transit, Bicycle, And Pedestrian Considerations..................................................................................... 20
Hybrid Beacons ....................................................................................................................................... 21
Design, Placement, And Location ........................................................................................................... 22
Operations (e.g., Time-Of-Day Plans, Periodic Retiming, Signal Coordination) ..................................... 22
Signal Removal ........................................................................................................................................ 24
Pavement Markings .................................................................................................................................... 24
Color ........................................................................................................................................................ 25
Retroreflectivity ...................................................................................................................................... 26

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 Type Of Material ..................................................................................................................................... 26
Location And Placement (e.g., Longitudinal Versus Transverse) ............................................................ 26
Pattern .................................................................................................................................................... 27
Surface Versus Inlaid Application ........................................................................................................... 27
Transit, Bicycle, And Pedestrian Considerations..................................................................................... 28
Installation And Removal ........................................................................................................................ 28
Roadway/Railroad Grade Crossings ............................................................................................................ 28
Type Of Control ....................................................................................................................................... 29
Sight Distance.......................................................................................................................................... 30
Signal Preemption ................................................................................................................................... 30
Queue Management ............................................................................................................................... 30
Work Zones And Temporary Traffic Control ............................................................................................... 30
Types Of Work Zones (e.g., Temporary Versus Long-Term) ................................................................... 31
Signing, Markings, Taper Lengths, And Channelizing Devices ................................................................ 34
Motorist Information (e.g., Communication) ......................................................................................... 35
Queue Management (e.g., Detours) and Roadway Capacity.................................................................. 36
Flagging Operations ................................................................................................................................ 36
Temporary Traffic Signals ....................................................................................................................... 36
Potentially Hazardous Conditions ........................................................................................................... 36
Temporary Traffic Control Plans ............................................................................................................. 37
Transportation Management Plans ........................................................................................................ 37
Speed Management ................................................................................................................................ 38
Road User Guidance.................................................................................................................................... 38
Signage And Markings ............................................................................................................................. 38
Advanced Warning .................................................................................................................................. 39
Changeable Message Signs ..................................................................................................................... 39
Human Factors ........................................................................................................................................ 39
Highway Advisory Radios ........................................................................................................................ 39
Traveler Information Systems ................................................................................................................. 39
Transportation Systems Management And Operations (TSM&O) Applications ........................................ 40
Traffic Signal Coordination...................................................................................................................... 41
Traffic Management Centers .................................................................................................................. 42
Video Surveillance................................................................................................................................... 42

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 Real-Time Traveler Information .............................................................................................................. 42
System Software ..................................................................................................................................... 42
Communication Media Between Signal Devices And Control Center .................................................... 42
Center-To-Center Communication (e.g., Law Enforcement, Media, Subcenters) .................................. 43
Dynamic And Changeable Message Signs ............................................................................................... 43
Ramp Metering ....................................................................................................................................... 43
Detection................................................................................................................................................. 43
Managed Lanes (e.g., HOV, Truck, Bus, Toll) .......................................................................................... 44
Traffic Incident Management .................................................................................................................. 44
Implementing TIM Programs .............................................................................................................. 45
School Zone Applications ............................................................................................................................ 46
Safe School Routes .................................................................................................................................. 47
Speed Management (e.g., Enforcement, Traffic Calming)...................................................................... 47
Traffic Control (e.g., Signs, Pavement Markings, Beacons, Crossing Guards) ........................................ 47
Pick-Up, Drop-Off, And On-Site Circulation ............................................................................................ 48
REFERENCES ................................................................................................................................................ 49

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 Professional Traffic Operations Engineer
Certification Program Refresher Course

Module 4 - Traffic Control Devices

Fundamentals of Traffic Control Devices
Success in the driving task depends on the drivers’ ability to receive and utilize information from many
sources. Deficient information increases the drivers’ chances of committing errors and increases the
potential for crashes. The purpose of the highway information system (traffic control devices) is to aid and
upgrade drivers’ performance. The principles of “positive guidance” are based on the premise that if the
driver can be given enough information when it is needed in a usable form, the driver can perform more
safely and efficiently.
Three levels of driver information needs have been identified:
• Navigation level of driver performance includes the planning
and execution of a trip. Information at this level comes from
maps, guide signs, and landmarks.
• Guidance level of driver performance refers to the task of
selecting a safe speed and path on the highway. This is a
decision process in which the driver must evaluate the immediate situation, make speed and path
decisions, and translate those decisions into control actions. Activities include lane positioning,
car following, overtaking, and passing. Information at this level comes from the roadway itself,
and from pavement markings and regulatory and warning signs.
• Control level of driver performance includes the physical manipulation of the vehicle. The driver
exercises lateral and longitudinal control of the vehicle through the steering wheel, accelerator,
and brake. Information at this level comes primarily from the vehicle itself and is received through
most of the drivers’ natural sense mechanisms.
Positive Guidance deals mainly with driver information needs at the guidance level. A failure occurs when
the driver selects an inappropriate speed or path and may result in a crash. A high percentage (up to 90
percent) of driver guidance information (or misinformation) is received visually. “Informal” sources of
information include traffic, roadway design features, tree lines, etc. “Formal” sources include signs,
signals, and markings, and must be used to supplement or compensate
for the information (or misinformation) from the informal sources.
Driver navigation information needs to be considered as well.
Although a failure at the navigation level may not be catastrophic, the
lost or confused driver is more likely to make an error at the guidance
level.
Drivers are usually able to handle highway guidance information and,
given enough time, make a decision and take proper action. Driver
error and improper actions may result from one or a combination of
the following factors:
• Information overload occurs when too many sources of
information compete, and drivers may miss key information.

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• Defective information display occurs when the informal

information sources provide erroneous information.
• Missing information such as safe curve speed, hidden
driveways, or control of intersection right of way is not evident
from the informal sources.
• Deficient traffic control devices may result in driver errors by
providing too much information, too little information,
obsolete or inappropriate information, or non- uniform
displays.
Design and placement of traffic control devices must consider human
factors relative to:
• Timing - drivers can best handle information at a steady rate,
avoiding “peaks” and “valleys” of information. System design
should provide for an even pacing of information, relocating,
or “spreading” lower priority information.
• Primacy - drivers respond to competing information sources
based on the apparent urgency or importance based on their
survival in the traffic stream. Devices with insufficient target
value may contribute to driver error.
• Expectancy - drivers respond more quickly and more predictably to situations that they expect to
encounter. One purpose of traffic control devices is to give advance notice of an unexpected event
or situation.
• Redundancy - providing the same information in more than one way may be critically important
to overcome driver inattention or at locations where the driver may miss needed information.

Manual on Uniform Traffic Control Devices

Note: This document primarily discusses the Manual on
Uniform Traffic Control Devices (MUTCD) as published by the
United States Federal Highway Administration. The current
edition at the time of the preparation of this study guide is
the 2009 Edition with Revision 3. The Federal Highway
Administration is currently preparing the 11th Edition of the
MUTCD, which is anticipated to be adopted in mid-2023.
Significant changes are anticipated in the 11th Edition.
In Canada, the Transportation Association of Canada (TAC)
publishes the Manual of Uniform Traffic Control Devices for
Canada (MUTCDC); the MUTCDC is a common starting point,
as provinces adopt their own laws, regulations, and manuals
on traffic control devices. The current edition is the 6th
Edition. These are some significant differences between the
United States and Canadian manuals.

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Other countries have similar documents defining the requirements for traffic control devices.
For practice within countries outside the United States, the local equivalent of the MUTCD
should be consulted.
The purpose of the MUTCD is to promote uniformity in the design and application of traffic control
devices.
The MUTCD contains five basic criteria for any traffic control device:
• It must fulfill a need
• It must command attention of road users
• It must convey a clear, simple meaning
• It must command the respect of road users
• It must give adequate time for proper response
These basic requirements should be applied in the planning, design, placement, operation, and
maintenance of all traffic control devices. Traffic control devices should be planned and implemented as
a system, taking into consideration the functional classification of the roads, which comprise the system.
These basic requirements should be applied to the periodic review of the existing system of traffic control
devices as well as to the implementation of new devices. Traffic control devices should be applied only on
the basis of need, exercising appropriate engineering judgment, and evaluating need relative to nationally
recognized standards, warrants, criteria, and available research results.
Uniform design and application of traffic control devices improves driver expectancy since the driver will
encounter signs and markings, which convey similar information under similar circumstances
throughout the country. By using uniform shapes, colors, and symbols, the information is “coded” to
help drivers process information more quickly and correctly.
The words “shall,” “should,” and “may” are defined in the MUTCD as follows:
• Shall: a mandatory condition. Where certain requirements in the
design or application of the device are described with the “shall”
stipulation, it is mandatory that these requirements be met when
an installation is made. This is a “standard”.
• Should: an advisory condition. Where the word “should” is used,
the action is advised; recommended but not mandatory. This is
“guidance”.
• May: a permissive condition. No requirement for design or application is intended. This is an “option”.
The MUTCD defines the following terms as well:
• Engineering judgment: “The evaluation of available information,
and the application of appropriate principles, standards, guidance,
and practice as contained in (the MUTCD) and other sources, for
the purpose of deciding upon the applicability, design, or
installation of a traffic control device. Engineering judgment shall
be exercised by an engineer, or by an individual working under the

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supervision of an engineer, through the application of procedures and criteria established by the
engineer. Documentation of engineering judgment is not required.”
• Engineering study: “The comprehensive analysis and evaluation of available pertinent information,
and the application of appropriate principles, standards, guidance, and practice as contained in (the
MUTCD) and other sources, for the purpose of deciding upon the applicability, design, or installation
of a traffic control device. An engineering study shall be performed by an engineer, or by an individual
working under the supervision of an engineer, through the application of procedures and criteria
established by the engineer. An engineering study shall be documented.”

Signing
Signs provide road users with information about regulations and provide the warning and guidance
needed for road users. Sign applications, designs, and installations
need to provide for uniformity throughout the roadway network;
uniformity simplifies the task of the road user because it aids in
recognition and understanding, thereby reducing perception/reaction
time, and assists road users, law enforcement officers, and traffic
courts by giving everyone the same interpretation. Signs should be
used only where justified by engineering judgment or studies, and
roadway geometric design and sign application should be coordinated so that signing can be effectively
placed to give the road user any necessary regulatory, warning, guidance, and other information.

Dimensions
The MUTCD and a companion document, the “Standard Highway Signs and Markings” book, provide
details related to the dimensions of highway signs. The basic requirements of a sign are that it be legible
to those for whom it is intended and that it be understandable in time to permit a proper response. The
appropriate attributes for sign design include:
• High visibility by day and night; and
• High legibility (adequately sized letters, symbols, or arrows, and a short legend for quick
comprehension by a road user approaching a sign)
Sign shapes reflect their function and are defined in the MUTCD as follows:
Shape Signs
Octagon Stop
Equilateral Triangle (1 point down) Yield
Circle Grade Crossing Advance Warning
Pennant Shape/ Isosceles Triangle (longer axis horizontal) No Passing
Pentagon (pointed up) School Advance Warning Sign (squared bottom corners)
County Route Sign (tapered bottom corners)
Crossbuck (two rectangles in an "X" configuration) Grade Crossing
Diamond Warning Series
Rectangle (including square) Regulatory Series
Guide Series
Warning Series
Trapezoid Recreational and Cultural Interest
Area Series
National Forest Route Sign

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The MUTCD provides design details for up to five different sizes,

depending on the type of traffic facility, including bikeways. Smaller
sizes are designed to be used on bikeways and some other off-road
applications. Larger sizes are designed for use on freeways and
expressways and can also be used to enhance road user safety and
convenience on other facilities, especially on multi-lane divided
highways and on undivided highways having five or more lanes of
traffic and/or high speeds. The intermediate sizes are designed to be used on other highway types.

Location And Spacing

In general, roadside signs in rural areas shall have a mounting height
of at least 5 feet (1.5 m) above the near edge of pavement. In areas
where parking or pedestrian movements occur, the clearance to the
bottom of the sign shall be at least 7 feet (2.1 m). If a secondary sign is
mounted below another sign, the bottom of the secondary sign may
be 1 foot (0.3 m) lower than the mounting heights specified above.
When signs are mounted over the roadway, the minimum vertical
clearance is 17 feet (5.2 m).
For ground-mounted signs, the minimum lateral offset should be 12 feet (3.6 m) from the edge of the
traveled way, or 6 feet (1.8 m) from the outside edge of shoulder, whichever is greater. However, in urban
areas where sidewalk width is limited or where existing poles are close to the curb, a minimum offset of
1 foot (0.3 m) from the face of curb may be used; some agencies require more, particularly for snow
storage.

Message Clarity
Standardized colors and shapes are specified in the MUTCD so that the several classes of traffic signs can
be promptly recognized. Simplicity and uniformity in design, position, and application are important.
Uniformity in design includes shape, color, dimensions, legends, borders, and illumination or
retroreflectivity.

Highway Fonts
Sign lettering is required to be in upper case letters, except that the
names of places, streets, and highways shall be a combination of
lower-case letters with initial upper-case letters. The standard
alphabets used for signs shall be as shown in the “Standard Highway
Signs and Markings” book; fonts based on different widths are
designed as series B, C, D, E, E(modified), and F.
A new font, known as Clearview, was developed as an alternative to the standard alphabets described
above. FHWA provided interim approval to use Clearview on positive contrast guide signs (white legends
on green, blue, or brown backgrounds); some agencies adopted the font for their guide signs. FHWA
revoked the interim approval in 2016; however, a reinstatement was provided that allowed previously
approved agencies to continue to use the font.

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Colors
Standard colors have been defined for use on traffic signs; they indicate the general nature of the
message. The color codes include:
• Red – Regulatory
• Yellow – Warning
• Green – Guide
• Blue – Services
• Orange – Construction
• Brown – Recreation
• Fluorescent Yellow-Green – School Crossing
• Fluorescent Pink – Incident Management
• Purple – Electronic Toll Collection
An approved fluorescent version of the standard red, yellow, green, or orange color may be used as an
alternative to the corresponding standard color. The colors coral and light blue are being reserved for uses
that will be determined in the future by the Federal Highway Administration.

Retroreflectivity
Regulatory, warning, and guide signs and object markers shall be
retroreflective or illuminated to show the same shape and similar color
at night as well as during the day (unless specifically exempted by the
MUTCD. Retroreflection means that the light from vehicle’s headlights
striking the sign is reflected directly back to the light source. Because
the driver of a vehicle is located relatively close to the headlights of
the vehicle, retroreflectivity provides drivers with the ability to see
signs at nighttime.
Sign retroreflectivity is typically provided either by spherical glass beads or prismatic reflectors in the sign
material. The retroreflectivity of sign materials gradually deteriorates as the sign ages. The MUTCD
contains “minimum maintained retroreflectivity guidelines” for signs. These criteria provide guidance for
the replacement of signs as nighttime brightness degrades. Highway agencies must have a program to
ensure that signs maintain adequate retroreflectivity, such as periodic nighttime visual inspection,
measurement of retro- reflectivity, or periodic replacement based on sign life expectancy.
As an alternative to retroreflectivity, the sign can be illuminated using either external or internal lighting
sources. Normal street lighting or other ambient lighting is not considered adequate to fulfill this
requirement.

Regulatory, Warning, And Guide Signs

Signs are classified as regulatory, warning, guide, and motorist information signs.

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Regulatory Signs
Regulatory signs inform the road user of a law, regulation, or legal
requirement. They indicate where these regulations apply in cases
where this would not otherwise be apparent. In some cases, a
resolution or ordinance must be approved for the regulatory sign to
have a legally enforceable meaning.
Regulatory signs should be placed at the beginning of the section of
roadway where the regulation applies and repeated periodically throughout extended sections.
Some regulatory signs are critically important in conveying essential information to the road user.
However, many of these same signs may not command the respect of road users, because of excessive
use (such as STOP signs) or because of inappropriateness of regulation (such as unrealistically low speed
limits).
Selection and implementation of regulatory signs must be based on an engineering study which considers:
• Recognized warrants or criteria
• Realistic assessment of the roadway, traffic, and environment
• Evaluation of alternative countermeasures
• Based on a systems plan
Regulatory signs are generally rectangular in shape with a white background and black (or red in the case
of a prohibition) legend. Regulatory signs include:
• Right of way series such as STOP signs or YIELD signs. The sign
should be placed at or near the point where the driver is
required to stop and may be supplemented with a STOP line
or YIELD line on the pavement. If a crosswalk has been
established, the sign should be located about 4 ft. (1.2) m in
advance of the crosswalk, and even with the stop bar if it is
present. If sight distance to the STOP or YIELD sign is limited, a
STOP AHEAD or YIELD AHEAD sign should be installed.
• Speed series such as speed limit, speed zone ahead, and school speed zone signs. Speed zones
should be established based on an engineering study of prevailing roadway speeds (as a primary
factor), roadway and environmental factors, and crash history. Unrealistically low speed zones are
difficult to enforce and often have poor compliance.
• Lane Use and Movement series such as turn restrictions, lane use, one-way, and vehicle exclusion
signs. Where restrictions or prohibitions are required, the signs should be highly conspicuous with
lettering large enough to be read by drivers approaching the location of the restriction.
• Parking series signs regulate the use of the curb lane and other parking areas.
• Pedestrian series signs regulate pedestrian crossings.
• Traffic control signal series regulate traffic movements at signalized intersections.

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• Miscellaneous regulatory signs include weight limit, ROAD CLOSED, TURN ON HEADLIGHTS, etc.
signing.

Warning Signs
Warning signs inform road users of conditions on or adjacent to the
roadway that potentially could be hazardous. These conditions may
violate normal driver expectancy and/or may require extra decision-
making time to determine an appropriate response. Warning signs are
generally diamond-shaped with a yellow (or florescent yellow-green
for pedestrian, bicycle, and school signs) background and a black
legend.
To be effective, warning signs must be placed far enough in advance of the hazard so that drivers can take
appropriate actions. Warning sign location in advance of the hazard depends on speed, PRT
(perception/reaction) time, and (where applicable) the amount of speed reduction or maneuver distance.
PRT times range from 2.5 sec. for general warning signs to 14.5 sec. for signs requiring a high degree of
judgment and response from the driver. PRT time should also be used to determine minimum spacing
between warning signs. See Table 2C-4 of the MUTCD for warning sign placement criteria.
Warning signs are critical to road user safety, yet they may not motivate drivers to take appropriate action.
In some cases, this is because the warning may be non-specific or may apply only in rare instances.
Warning signs should be used sparingly, but when used should have primacy over other traffic control
devices. Conspicuity or target value of warning signs may have to be reinforced through redundancy
(multiple signs, flashing lights, pavement markings, etc.).
Warning signs include:
• Alignment series such as curve, turn, large arrow, and chevron
signs. The use of alignment series signs should be limited to
locations where the change in alignment is not apparent,
where a speed reduction of more than 5 mph (10 km/h) would
be required for comfortable operation, or where traffic
engineering studies indicate a need. A supplemental speed
advisory plate may be needed based on the results of a ball-
bank indicator test or other analysis of curve design speed.
• Intersection series such as crossroad, side road, T-intersection, and double- headed arrow signs.
Such signs may be useful at locations with limited visibility, where the intersection would be
unexpected, or where accident history indicates a need. They are not normally used where
junction or advanced route turn guide signs are in place.
• Traffic control series such as STOP AHEAD, YIELD AHEAD and
SIGNAL AHEAD. These signs are used when drivers do not have
sufficient visibility of the intersection traffic control device to
take appropriate action. See Table 4D-1 of the MUTCD for
minimum traffic signal visibility criteria.
• Cross section series such as road narrows, narrow bridge, and
divided highway signs. Where a lane is dropped, the warning sign location should provide drivers
with 14.5 sec of PRT time.

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• Advance crossing and crossing series such as pedestrian, bicycle, trucks, deer, etc. Only critical
locations (such as restricted sight distance, young or elderly pedestrians, or an accident history)
should be signed. School areas require special attention, focusing on the area adjacent to the
school and along designated school routes. The color “florescent yellow-green” is approved for
use for pedestrian, bicycle, and school zone warning signs. The current MUTCD also eliminated
the use of “crosswalk” lines on warning signs placed at the location of crossings. Instead, the
standard warning sign is supplemented with an angled down arrow to indicate the crossing
location.
• Surface conditions series such as Slippery When Wet, Pavement Ends, and Bump signs.
The MUTCD states that horizontal alignment warning signs on freeways, expressways, and roadways
functionally classified as arterials or collectors with an AADT of more than 1,000 vehicles per day shall be
in accordance with Table 2C-5. Signs designated as “Required” in Table 2C-5 are mandatory.
“Recommended” indicates that the sign is recommended but not mandatory. “Optional” means that the
sign may be installed but no recommendation is implied. The MUTCD indicates that Turn or Reverse Turn
signs shall be used (rather than Curve or Reverse Curve signs) where the advisory speed is 30 mph (50
km/h) or less. The Curve or Reverse Curve signs are used where the advisory speed is greater than 30 mph
(50 km/h).

Guide Signs
Guide signs provide navigation information, including route
designations, destinations, directions, distances, services, points of
interest, and other geographical, recreational, or cultural information
to assist road users in reaching their intended destinations. A high level
of guidance is essential to minimize confusion and to optimize safety
and efficiency of traffic flow. The principles of primacy, timing, and
spreading are important in the placement of guide signs. Redundancy
may be important to reassure drivers that they are on the desired route. Guide signs include street name
signs, route signs, destination and distance signs, and freeway and expressway interchange identification
signs.
Guide signs generally have green (or brown for recreational and cultural interest signs) backgrounds and
white legends. The MUTCD requires that the lettering for names of places, streets, and highways on guide
signs shall be a combination of lower-case letters with initial upper-case letters. The nominal loop height
of the lower-case letters shall be 3/4 the height of the initial upper-case letter.

Motorist Information Signs

Motorist information signs provide information about facilities,
services, businesses, and attractions on or near roadways. They
include general services indicating the availability of gas, food, lodging,
etc.; specific services (specific business identification for gas, food,
lodging, and attractions); recreational and cultural interest attractions
and traffic generators and tourist-oriented businesses. Motorist
information signs generally have blue backgrounds and white legends.

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Changeable Message Signs

Changeable message signs can display more than one message. They
may be changed manually, by remote control, or by automatic
controls. Such signs should be limited to not more than three lines with
not more than 20 characters per line. No more than two displays
should be used within any message cycle. The entire message should
be readable at least twice by drivers traveling at prevailing speeds. The
signs should not be used to display information other than regulatory,
warning, and guidance information related to traffic control. The use of animation, rapid flashing, or other
dynamic elements is not allowed.

Transit, Bicycle, And Pedestrian Considerations

In addition to signs designed for general motor vehicle traffic on roadways, special signs have been
developed for transit, bicycles, and pedestrians:
• Section 2G of the MUTCD addresses signing for preferential
lanes, which are lanes designated for special traffic uses such
as high-occupancy vehicles (HOVs), light rail, buses, taxis, or
bicycles.
• Signs for bicycle facilities are addressed in Part 9 of the
MUTCD, including bikeways, shared use paths, and bicycle
lane facilities.
• Signing for pedestrians include signs defined in Part 2 of the MUTCD, which includes pedestrian
restriction and warning signs, and in Part 7, which includes traffic control for school areas.

Sign Supports
Sign supports must be durable and structurally adequate to withstand
wind and ice loading. At the same time, they should not present a
hazard to road users and should fail in a safe and predictable manner
when struck by a vehicle. Post-mounted signs shall be crashworthy or
shielded with a longitudinal barrier or crash cushion if located within
the clear zone. On impact, the sign supports must break away, yield,
bend over, or fracture. After impact, the “stub height” of the support
remaining in the ground should not exceed 4 inches (100 mm) to avoid snagging the undercarriage of the
vehicle. Because large overhead sign support structures cannot be made to break away on impact, they
should be suitably shielded if located within the clear zone on a high-speed road.

Maintenance Of Traffic Control Signs

To ensure that road users have adequate opportunities to perceive and evaluate the information
contained on traffic control devices, the devices must be visible, well maintained, and effective in
communicating their message. The performance of traffic control devices is a critical issue as attention is
focused on the visual needs of older drivers and pedestrians. This is especially critical when driving at
night.
Traffic control device management (TCDM) is a program which is useful in determining:
• Type and number of devices present

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• Location
• Condition
• Effectiveness under various environmental conditions
• Work history of the devices
• Strategies for replacement.
TCDM requires an accurate inventory system, routine field inspections, a responsive and preventive
maintenance effort, and a replacement program. A proper management program can help agencies
maintain the effectiveness of their traffic control devices. Thorough documentation of this management
process can also strengthen defense in cases of legal claims.
The main objectives of a TCDM program are:
• Classification of all signs and markings by type, size, location,
condition of sign and post, and performance during the day
and at night.
• Discovery of conditions requiring a change in the size, location,
or type of sign; repair of the sign or post; replacement with a
new or refurbished sign.
• Plan for personnel effort and budget needed to adequately operate the TCDM program and to
develop a plan for implementing needed changes.
An important part of the ongoing TCDM process is the performance of routine field inspections. This
allows discovery of conditions requiring further attention. The follow-up action might entail repair,
replacement, or minor maintenance such as cleaning. Obstructions which restrict visibility, such as tree
limbs, bushes, weeds, or parked cars can be identified and noted for further action. Obsolete and non-
standard devices as well as devices which are no longer needed should be targeted for removal.
These inspections must be conducted both during the day and at night. As a general guide, at least one
daytime and one night inspection should be conducted on a yearly basis. The dates of each inspection
should be logged into the TCDM program. Employees of the highway or transportation agency, the police
department, and other governmental workers whose duties require that they travel on streets and
highways should be encouraged to report any damaged or obscured sign which they observe.

Maintaining Adequate Retroreflectivity

In order to remain reasonably visible at night, signs must maintain an adequate level of retroreflectivity.
Various methods can be considered for rating sign retroreflectivity.
• Visual Night Inspection. The retroreflectivity of a sign is
assessed by a trained sign inspector conducting a visual
inspection from a moving vehicle during nighttime conditions
using one or more of the following procedures:
• Calibration Signs. Prior to conducting a night sign inspection,
the sign inspector views sample signs that are at or near the
minimum retroreflectivity levels. These signs are viewed at night from the vehicle to be used
during the inspection and at distances that are representative of normal sign viewing distances.

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During the actual inspection, the inspector identifies signs that should be replaced based on how
their retroreflectivity compares to the calibration signs.
• Constant Parameters. The factors that influence night visibility (such as vehicle type, headlights,
view distance, driver age, and driver eyesight) are kept similar to the factors used to develop the
minimum retroreflectivity levels. The inspector identifies signs that should be replaced based on
a visual assessment.
• Comparison Panels. Small comparison panels at the minimum levels of retroreflectivity are used
to assess the retroreflectivity of a sign. A comparison panel is temporarily attached to an existing
sign in the field. An inspector views the sign and comparison panel combination at night. The
inspector identifies signs that should be replaced based on how their retroreflectivity compares
with the comparison panels.
• Measured Sign Retroreflectivity. Sign retroreflectivity is measured using a retroreflectometer.
Signs with retroreflectivity below the minimum levels should be replaced.
• Expected Sign Life. When signs are installed, the installation date is labeled or recorded so that
the age of a sign is known. The age of the sign is compared to the expected sign life. The expected
sign life is based on the experience of sign retroreflectivity degradation in a geographic area. Signs
older than the expected life should be replaced.
• Blanket Replacement. All signs in an area/corridor, or of a given type, should be replaced at
specified intervals. This eliminates the need to assess retroreflectivity or track the life of individual
signs. The replacement interval is based on the expected sign life for the shortest-life material
used on the affected signs.
• Control Signs. Replacement of signs in the field is based on the performance of a sample of control
signs. The control signs might be a small sample located in a maintenance yard or a sample of
signs in the field. The control signs are monitored to determine the end of retroreflective life for
the associated signs. All field signs represented by the control sample should be replaced before
the retroreflectivity levels of the control sample reach the minimum levels.
Maintenance records should be kept to document activity related to traffic control device inspections and
repairs. The date and time the agency was informed of a condition requiring investigation should be
recorded. The record should also include the name of the initiating party, actions taken, and when
completed. Other problems observed while responding to the maintenance request should be noted too.
These records are useful in future planning of maintenance force requirements and in legal defense cases.
Success and failure rates with different installation techniques, materials, or equipment can be
determined through monitoring and analyzing these maintenance records. In addition, as part of a
continuing maintenance and upgrading program, devices needing replacement can be scheduled on a
district or system wide basis.
To effectively plan a sign replacement schedule, monitor changes to the devices and reduce legal liability
through accurate documentation, an ongoing TCDM program is essential. The program consists of an
inventory of existing devices, a method to analyze, change and update the data, timely replacement of
devices at the end of service life, and adherence to established standards regarding sign type, application,
and design. If these guidelines are followed and the system is well organized, the agency is in a position
to defend itself against claims of negligence related to the placement or condition of traffic control
devices. It can also be reasonably certain the traffic control devices in place are performing as intended.

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Traffic Signals
Traffic control signals are power-operated signal displays. The primary function of a traffic signal is to
alternately assign the right-of-way to various traffic movements at an intersection or other roadway
location.
When properly located, designed, operated and maintained, traffic
control signals have the following potential advantages:
• Provide for the orderly movement of traffic
• Reduce the frequency of certain types of crashes (e.g., right
angle, crossing pedestrian, and possibly left turn)
• Increase the capacity of the minor street approaches
• Provide a means of interrupting heavy traffic flows to allow other traffic to enter or cross the
intersection
When poorly located, designed, operated or maintained, traffic
control signals have the following potential disadvantages:
• Increase delay and excess fuel consumption, especially during
off- peak periods
• Increase the frequency of certain types of crashes (e.g., rear
end, lane change, turning vehicle-pedestrian, and possibly
left turn)
• Result in driver frustration, and possible loss of respect for the device
• Induce road users to use alternative, less appropriate, routes to avoid such signals
The capability and commitment of the agency for proper maintenance of a traffic control signal should
be carefully considered early in the planning and design stages.

Signal Warrant Studies

Traffic control signals should not be installed unless one or more of the nine warrants contained in the
MUTCD are satisfied. In evaluating the MUTCD signal warrants, it is presumed that if installed, the device
will be properly operated and maintained, the geometric design of the intersection is adequate, nearby
traffic control signals are properly coordinated, and that the intersection control will be selected based
on a traffic engineering study and judgment. Satisfying one or more warrants is a necessary, but not
sufficient, indication of the need for signal control. The MUTCD signal warrants include:
• Eight-hour vehicular volume
• Four-hour vehicular volume
• Peak hour
• Pedestrian volume
• School crossing
• Coordinated signal system

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• Crash experience
• Roadway network
• Intersection near a Railroad Grade Crossing
See the MUTCD and Traffic Control Devices Handbook for additional discussion of traffic signal warrants.

Detection
Actuated traffic signal controllers use detectors to identify the demand
for a movement at an intersection and to relay that information to the
traffic signal controller. Detectors include multiple technologies and
can be used to sense vehicles, pedestrians, and bicycles.
Vehicle detection technologies include inductive loops,
magnetometers, magnetic detectors, microwave radar sensors,
infrared, ultrasonic, acoustic, and video image processing. The placement and configuration of these
vehicle detectors is based on the operating strategies and characteristics for the intersection, including
the speeds and number of lanes on the approaches.
Pedestrian detection includes active detection (primarily push buttons) and passive detection (typically
microwave, infrared, and video image processing technologies). The detection of bicycles is seeing
increased application and include a variety of technologies.

Signal Displays
Vehicle signal lens may be either 8 inches (200 mm) or 12 inches (300 mm) in diameter. The 12-inch (300-
mm) lenses are required by the MUTCD for new signal faces, except:
• Downstream signals where signals are closely spaced
• Circular indications where the posted speed limit is less than
30 mph
• Circular indications for a supplemental near-side signal
• Supplemental signal for the sole purpose of controlling
pedestrians or bicycles
Existing 8-inch (200 mm) signal lenses may remain in place for the remainder of their useful life.
A relatively recent addition to signal operations is the Flashing Yellow Arrow display for a permissive left
turn movement. Developed to address concerns of motorist comprehension of the circular green
indication for a permissive turn and the “yellow trap” or “left turn trap” (where a driver turning left on a
circular yellow indication may wrongly assume that opposing traffic is also stopping), the Flashing Yellow
Arrow is associated with the opposing green movement. The Flashing Yellow Arrow signal display can also
be used to restrict turns to protected only mode by time-of-day or even on a cycle-by-cycle basis.

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Pedestrian signal heads use symbolic WALKING PERSON and UPRASIED

HAND indications, although many installations with the word
messages WALK and DON’T WALK are still in use. The MUTCD requires
the use of pedestrian signal heads if the traffic signal meets Warrant 4
(Pedestrian Volume) or Warrant 5 (School Crossing), if the signal
operates with an exclusive pedestrian phase, at any established school
crossing, or where signal phasing may be confusing to pedestrians.
Accessible pedestrian signals are devices that communicate information about pedestrian timing in non-
visual format such as audible tones, verbal messages, and/or vibrating surfaces. The need for accessible
pedestrian signals at an intersection may be indicated by citizen requests, traffic volumes during periods
when pedestrians might be present, high volumes of right-turn-on-red, complex signal phasing, or
complex intersection geometry.
Countdown pedestrian signals display the number of seconds remaining in the pedestrian change interval.
The countdown begins at the beginning of the flashing UPRAISED HAND display and ends at the beginning
of the vehicle yellow change interval. The MUTCD requires the installation of countdown displays at all
pedestrian signal heads at crosswalks where the pedestrian change interval is more than 7 seconds.

Phasing And Timing (e.g., Clearance Intervals, Preemption)

A traffic signal phase is defined as the sum of the Green right-of-way, Yellow Change, and Red Clearance
intervals in a cycle that are assigned to an independent traffic movement of combination of movements.
An interval is the part of a signal cycle during which signal indications do not change.
A standardized phase numbering system has been adopted that
organizes phases by grouping them into continuous loops, referred to
as rings. Crossing or conflicting movements are separated by making
the movements sequential within the same ring, or by adding a barrier
between phases for one street and the phases for the conflicting
street. At any given time, the signal may display one phase from one
ring and one phase from the other ring, but not two phases from the
same ring. Both rings cross the barriers at the same time to ensure that conflicting movements from the
two crossing streets are not served at the same time.
The phasing and sequencing of a traffic control signal affect both the
safety and efficiency of intersection traffic operations. Basic principles
of signal phasing include:
• The number of phases used depends on the geometric design
of the intersection (number of approaches, lanes, exclusive
left-turn lanes), volume and directional movements of
vehicular traffic, and pedestrian crossing requirements.
• The purpose of phasing is to minimize the potential hazards at the intersection through the
separation of conflicting vehicular and pedestrian movements. However, this must be
accomplished without substantially reducing the efficiency of traffic flow.
• Consideration must be given to the fact that as the number of phases is increased, the total delay
to vehicles is increased and the traffic carrying capacity of the intersection may be reduced.

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At many locations, determinations must be made regarding the

provision of separate protected left-turn phases. Two “rules of thumb”
are commonly used to determine if separate left turn phases are
required; check with your appropriate jurisdiction for specific
requirements:
• If the volume of left turning vehicles exceed 100 vehicles per
hour, and
• If the product of the number of left turning vehicles times the opposing volume exceeds 50,000.
Where protected left-turn phases are provided, the left-turn traffic should be accommodated with a
combination of protected and permitted phasing wherever practicable in order to maximize capacity and
efficiency. A flashing yellow arrow can be displayed during the permissive left-turn period to emphasize
the need for left-turners to yield to oncoming traffic.
At locations where left-turning volumes are very high (e.g., more than 300 left turns per hour), multiple
left-turn lanes may be needed to meet user demands. If two or more left turn lanes are provided, this
movement should generally be made during a protected phase without opposing traffic.
The objective should be to devise the simplest design and the minimum number of phases that will
accommodate the existing and anticipated future traffic demands.
The timing of intervals within the sequence of operation for the traffic control signal must be determined
based on the type of the controller unit and the operational requirements of the intersection. Pre-timed
and actuated control are timed differently because of the inherent differences in operational philosophy
and functional characteristics of these control types. Timing strategies may also differ depending on
whether the intersection is isolated or part of a signal system. However, the following guiding principles
generally apply to all modes of control:
• Relatively short-cycle lengths tend to improve performance in
terms of minimizing overall intersection delay, provided that
the capacity of the intersection is not exceeded.
• If all traffic movements are to be provided with equal quality
of service, the green intervals lengths should be set
proportional to traffic demand volumes on a per-lane basis.
• The phase-change intervals (yellow change and possibly a red
clearance) for each phase must be determined to ensure that
approach vehicles can either stop or clear the intersection
without conflicts once the yellow change interval begins. The
MUTCD indicates that the yellow change interval should be
“approximately 3 to 6 seconds.” The ITE Recommended
Practice for determining the yellow change interval uses the
equation for US units:

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where:
𝑌𝑌 = minimum yellow change interval (sec.)
𝑡𝑡 = perception-reaction time (sec.)
𝑉𝑉85 = 85th percentile approach speed (mph)
𝑉𝑉𝐸𝐸 = intersection entry speed (mph)
𝑎𝑎 = deceleration (ft./sec./sec.)
𝑔𝑔 = grade of approach (percent/100, downhill is
negative grade)

Or for Metric units:

where:
𝑌𝑌 = minimum yellow change interval (sec.)
𝑡𝑡 = perception-reaction time (sec.)
𝑉𝑉85 = 85th percentile approach speed (km/h)
𝑉𝑉𝐸𝐸 = intersection entry speed (km/h)
𝑎𝑎 = deceleration (m/sec./sec.)
𝑔𝑔 = grade of approach (percent/100, downhill is negative grade

The Red Clearance interval is calculated in US units as:

Where:
𝑅𝑅 = red clearance interval (sec.)

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𝑊𝑊 = distance to traverse the intersection (width), stop

line to far side no-conflict point along the vehicle path
(ft.)
𝐿𝐿 = length of vehicle (ft.)
𝑉𝑉𝐸𝐸 = intersection entry speed (mph)
𝑡𝑡𝑠𝑠 = conflicting vehicular movement start up delay (sec.)

Or, for Metric Units:

Where:
𝑅𝑅 = red clearance interval (sec.)
𝑊𝑊 = distance to traverse the intersection (width), stop line to far side no-conflict point
along the vehicle path (m)
𝐿𝐿 = length of vehicle (m)
𝑉𝑉𝐸𝐸 = intersection entry speed (km/h)
𝑡𝑡𝑠𝑠 = conflicting vehicular movement start up delay (sec.)

Where pedestrians are present, interval timing must accommodate their crossing time. Timing for
pedestrians must account for:
• Pedestrian start-off time
• Pedestrian clearance time
• Buffer time
The start-off time must be long enough to permit all pedestrians who
are waiting to cross enough time to step into the street and start
crossing. During the start-off time, the pedestrian signal heads display
the WALKING PERSON symbol. The MUTCD indicates this period should
be at least 7 seconds but may be reduced to 4 seconds under unusual
circumstances. Where pedestrian traffic is heavy, a longer start-off
time may be needed.

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Pedestrian clearance time is the time needed to complete the street

crossing, at least as far as the far edge of the farthest traveled lane, or
to a median wide enough for pedestrian storage. The clearance time is
calculated as D/S where D is the crossing distance and S is the walking
speed of the pedestrians. Normally a walking speed of 3.5 feet/second
(1.1 m/sec) should be used. However, if the crossing is used by people
who may not be able to travel at this speed, such as wheelchair users,
then a lower walking speed should be considered. Also, if the crossing
is heavily congested, a lower walking speed may be appropriate. A
walking speed of 4 ft/sec (1.2 m/sec) may be used if there is an
opportunity for slower moving pedestrians to actuate a longer
clearance time by using an extended pushbutton push, or through
passive detection of pedestrians remaining in the crosswalk.
The pedestrian clearance time is the sum of the Pedestrian Change Interval plus the Buffer Interval.
During the Pedestrian Change Interval, the pedestrian signal displays a flashing UPRAISED HAND signal
indication. The MUTCD indicates that the Buffer Interval shall be at least 3 seconds long before any
conflicting vehicle traffic is released. The Buffer Interval may overlap some or all the vehicle Yellow Change
and Red Clearance intervals.
On high-speed approaches to signalized intersections, drivers may be
indecisive if the signal changes to yellow when the drivers are a few
seconds away from the intersection. The portion of the approach
where this indecisiveness tends to occur is referred to as the indecision
zone or dilemma zone. An inappropriate decision by such drivers may
result in either a rear-end collision or a right- angle collision.
To minimize the crash potential of the indecision zone, a vehicle actuated controller with appropriate
detection placement can be used. Because the area of indecision tends to lie in the range of 2.5 seconds
to 5.0 seconds of travel time upstream of the intersection, the traditional approach to providing dilemma
zone protection is to place advance detection at least 5.0 seconds travel time upstream of the
intersection. Then, a vehicle that has been detected within the last several seconds can be provided with
an extended green indication, so the driver is not confronted with a yellow signal. If no vehicles have been
detected in several seconds, then it is safe to end the green and begin a yellow signal because the closest
vehicle must still be more than 5 seconds away from the intersection and not within the zone of indecision.
At some locations, it is desirable to be able to transfer the normal
mode of signal control to a special signal control mode in order to give
priority to emergency vehicles or transit vehicles approaching the
intersection.
Railroad grade crossing signal preemption serves to ensure that the
separate railroad and highway traffic control systems do not conflict
with each other. Two potential problems that such preemption seeks
to avoid are:
• The queuing of highway traffic across the tracks at a grade crossing by an adjacent highway traffic
signal.

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• Interference to the operation of a highway traffic signal because of traffic backed up from a
downstream railroad grade crossing
Traditionally, the use of traffic signal preemption has been recommended whenever the distance between
the crossing and the signalized intersection is 200 ft. (60 m) or less. However, recent research has
indicated that this criterion is inadequate and that this distance be determined on the basis of the length
of the queue on the approach across the tracks created by the traffic signal.
The timing element that must be given foremost consideration to ensure the proper operation of signal
preemption is the warning time provided by the railroad active warning system to the traffic signal
controller assembly before arrival of a train. The proper warning time assures that the preemption
sequence can clear vehicles from the track before arrival of the train. In some cases, it may be acceptable
to shorten Green intervals and Pedestrian Walk and Clearance intervals in order to provide a Clear Track
Green interval as quickly as practicable.
Emergency vehicle preemption can be provided for any authorized emergency vehicle such as fire,
ambulance, or police. The purpose is to obtain a green signal for the emergency vehicle to give the vehicle
priority through the intersection. To obtain a green, the existing signal phase may be abbreviated, and
after a normal phase change interval, the green is transferred to the approach used by the emergency
vehicle. Normally, only that single approach receives the green. Preemption can be initiated by a
transmitter on the emergency vehicle or by a switch at the emergency vehicle base.
Transit vehicle priority is different than preemption in that its purpose is to modify the timing of the
normal sequence of operation to provide a green to the approaching transit vehicle sooner, rather than
transferring out of the normal sequence. Transit priority can be initiated by a transmitter on the transit
vehicle or by roadway detectors.

Transit, Bicycle, And Pedestrian Considerations

In addition to the pedestrian signals already discussed, special signals are provided as an option for both
bicycles and transit vehicles.
• Bicycle signals were given Interim Approval for use by FHWA
in 2013, after experimentation showed that they could be
effective in addressing specific concerns. These signals use
red, yellow, and green indications with the bicycle symbol
within the lenses. A Bicycle Signal sign is required to be placed
adjacent to the bicycle signal face. Currently, use is limited to
situations where bicycles moving on a green or yellow signal
indication are not in conflict with any simultaneous motor
vehicle movements. The operating agency must receive
approval from FHWA prior to installation.
• The MUTCD includes details for the optional use of special
signal indications consisting of white vertical, horizontal, or
angled bars in the section on Light Rail Transit Signals. In
addition, the MUTCD permits the us e of these indications for
bus transit applications if appropriate.

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• Accessible Pedestrian Signals (APS) are devices that

communicate information about the WALK and DON'T WALK
intervals at signalized intersections in non-visual formats to
pedestrians who are blind or who have low vision. APS can
provide information to pedestrians about:
o Existence of and location of the pushbutton
o Beginning of the WALK interval
o Direction of the crosswalk and location of the destination curb
o Intersection street names in Braille, raised print, or through speech messages
o Intersection signalization with a speech message
o Intersection geometry through tactile maps and diagrams, or through speech messages.

Hybrid Beacons
Hybrid beacons have been defined in the MUTCD for two primary applications:
• A Pedestrian Hybrid Beacon (PHB), sometimes referred to as a
HAWK signal, is used to warn and control traffic at an
unsignalized location to assist pedestrians in crossing a street
or highway at a marked crosswalk. A pedestrian hybrid beacon
may be considered for installation to facilitate pedestrian
crossings at a location that does not meet traffic signal
warrants or at a location that meets traffic signal warrants, but
a decision is made to not install a traffic control signal. Standard pedestrian signal faces are
provided for the crosswalk.
The PHB face consists of three signal sections, with a circular yellow signal indication centered
below two horizontally aligned circular red signal indications. The beacon is dark between
pedestrian activations, with the pedestrian indications displaying Don’t Walk. Upon activation,
the beacon will display a flashing yellow indication, followed by a steady yellow indication, and
then both red indications display a steady indication, at which time the Walk indication is
displayed. At the beginning of the pedestrian clearance interval, the pedestrian signal will display
Flashing Don’t Walk and the beacon will display an alternating red indication. Following
pedestrian clearance, the beacon will be dark, and the pedestrian indications will display Don’t
Walk.
• An Emergency Vehicle Hybrid Beacon is used in conjunction
with signs (EMERGENCY SIGNAL—STOP WHEN FLASHING RED)
to warn and control traffic at an unsignalized location where
emergency vehicle s enter or cross a street or highway. The
emergency vehicle hybrid beacon is similar in appearance to
the pedestrian hybrid beacon, but with a slightly different
operation. Normally, the beacon is dark. Upon activation, the
beacon will display a flashing yellow indication, followed by a steady yellow indication, and then
the two red indications flash alternately for the duration of the time needed for the emergency
vehicle to clear the location.

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Design, Placement, And Location

The MUTCD requires at least two signal faces for the major movement
on each approach to a signalized intersection. At least one, and
preferably both of these signal faces shall be at least 40 ft (12 m)
beyond the stop line and not more than 180 ft (55 m) beyond the stop
line (unless a supplemental near-side signal face is provided), and as
near as practical to directly in line with the drivers’ normal view, and
shall be located within a cone of vision 20o to the left and right of the
centerline of the approach, measured from a point 10 ft (3 m) in advance of the stop line.
Locating primary signal faces overhead on the far side of the intersection has been shown to provide safer
operation by reducing intersection entries late in the yellow interval and by reducing red signal violations,
as compared to post-mounting signal faces at the roadside or locating signal faces overhead within the
intersection on a diagonally oriented mast arm or span wire. On approaches with two or more lanes for
the through movement, one signal face per through lane, centered over each departing through lane, has
also been shown to provide safer operation.

Operations
Individual intersections must be timed and operated to provide for the safe and efficient movement of
road users (vehicles, pedestrians, and bicyclists) through the intersection, otherwise, the full benefits of
the installation will not be realized. In addition to the safety-related timings previously discussed (yellow
change, red clearance, and pedestrian clearance), green times should be developed to appropriately
allocate the right of way times to the various movements as necessary.
When two or more signalized intersections are close enough to each
other, consideration should be given to having them operate in
coordination with one another. Coordination means that there is a
predictable time relationship between the operations of each signal
relative to the operations of each of the other signals in the system.
One of the most cost-effective traffic operational improvements that
can be made in urban street systems results from the coordination of
traffic control signals along a street or within a network of streets.
The primary objective of signal coordination is to provide progression. The system will be progressive
when the time relationship between adjacent signals permits vehicles traveling at a planned speed to pass
through a green light at each intersection within the system without stopping. Advantages of progression
include:
• Reduction in overall travel time and delay
• Reduced frequency of stops, fuel consumption, air pollutant emissions, and vehicle operating
costs
• Reduction of crashes associated with stopping
• Built-in speed control

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Coordination can be achieved using a variety of techniques including time-based coordination, system
masters with interconnect to each local controller unit, or computer-
controlled systems.
Maintaining a consistent time relationship between adjacent signals
requires that the cycle lengths at all intersections within the system
must be the same. In systems where signals are spaced at
approximately even intervals along a street, a “first cut” estimate of an
efficient signal system cycle length can be calculated as:

where:
C = Signal system cycle length (sec.)
X = An integer (e.g., 1, 2, 3, etc.)
D = Average spacing between signals (ft or m)
V = Progression speed (ft/sec or m/sec)
The following factors will influence the desirability of system
operation, as well as the potential efficiency with which a system could
operate:
• Signal spacing. As a rule-of-thumb, signals that are located
within a distance of ½ mi. (1 km) or less should be considered
for system operation. However, even at greater spacing,
significant benefits may result from coordination. The desirability of system operation generally
increases as spacing between signals decreases; but the efficiency of system operation generally
increases as spacing increases. Irregular spacing also tends to degrade system efficiency.
• Directional movement. One-way operation greatly facilities progressive signal timing. This is true
whether it is a one-way street or a two-way street on which progression is only important in one
direction.
• Signal phasing. Multiple phases reduce the effective green time available to service the
coordinated through movements, and therefore tend to reduce system efficiency.
• Arrival patterns. If traffic arrives at the intersection in regular, dense platoons, progression
provides important benefits. Conditions which tend to break up platoons include excessive
distances between signals and high volumes of traffic turning onto and off of the street from
driveways or cross streets.
• Traffic fluctuations. Arrival characteristics and traffic volumes may vary greatly throughout the
typical day. Peak period conditions may indicate the need for system operation, but off-peak
conditions may best be served with isolated operation.
• Incompatible signal cycle requirements. To provide progression, all signals in the system must
operate on the same cycle length. The desirable cycle length for system efficiency may not provide

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efficient operation or adequate capacity at individual intersections within the system, and
compromises may have to be made. In some cases, a critical intersection can be operated at twice
or half the normal system cycle length.

Signal Removal
In many communities, due to lack of traffic engineering expertise, or political pressure, or both, traffic
signals have been installed at intersections where they are not warranted nor justified. In other cases,
signals may have been needed at one time, but changing conditions have reduced this need.
Many engineers are reluctant to attempt the removal of a signal,
fearing liability consequences. In reality, a reasonably analyzed,
carefully documented decision to reduce the restrictiveness of
intersection controls should not result in unreasonable risk of liability.
It must be recognized that traffic control signal removal often involves
institutional or political constraints; the removal decision process must
also include consideration of these factors in addition to the technical
issues.
Where a signalized intersection is to be converted to two-way stop control, three variables tend to have
a significant effect on the change in accident frequency:
• Adequacy of minor street sight distance
• Traffic volumes
• Average annual crash frequency prior to signal removal
Conditions favoring signal removal include adequate sight distance, lower traffic volumes, and a crash
frequency of at least two per year.
It is always easier to not install a signal initially than to put one in and then try to remove it later. An
agency needs to make some assessment of how well a new signal would fit into a future progression
system before the initial installation is made.

Pavement Markings
Pavement markings include lines, patterns, words, symbols, and other devices that are placed on or set
into the pavement surface for the purpose of regulating, warning, or guiding road users. Pavement
markings can be used to:
• Indicate regulations (no passing zones, mandatory turn lanes)
• Supplement other devices (stop lines)
• Guide road users (lane lines, crosswalks)
• Warn road users (Signal Ahead message, railroad crossing)
Pavement markings convey information in a “coded” form, using color, line design (solid, broken, width,
etc.), and number of lines.

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Pavement markings have definite limitations which must be recognized. They are obliterated by snow,
damaged by snow removal processes, including plowing and chemicals, hidden by stopped vehicles, may
lose visibility at night in the rain, and may wear rapidly under moderate to heavy traffic volumes, requiring
frequent maintenance. In spite of these limitations, pavement markings have the advantage, under
favorable conditions, of conveying information to road users without diverting attention from the
roadway.
A variety of pavement marking materials are available, including paint,
thermoplastic, epoxy, pre-formed tape, raised retroreflective and non-
retroreflective markers, in-pavement lighting devices, etc. Relative
costs, longevity, pavement type and condition, traffic volume, and
hazard to workers should be considered in selecting an appropriate
marking material.

Color
Colors used for pavement markings can include the following:
• White
o Longitudinal lines
 Separating traffic flows in the same direction
 The right-hand edge of the roadway
o Transverse markings
o Word, symbol, and arrow markings
o Crosswalk markings
o Chevron, diagonal, and crosshatch markings
• Yellow
o Longitudinal lines
 Separating traffic flows in opposing directions
 The left-hand edge of roadways on divided highways and one-way streets or
ramps
 The separation of two-way left turn lanes and reversible lanes from other lanes
• Red (typically raised reflective pavement markers)
o Truck escape ramps
o Wrong way movements
o Red colored pavement has been given interim approval by FHWA for use on transit lanes.
• Blue
o To supplement white markings for parking spaces for persons with disabilities
• Purple
o To supplement lane line or edge line markings for toll plaza approach lanes restricted to
vehicles with registered electronic toll collection accounts.
• Black is not considered a marking color but can be used to increase the contrast of other marking
colors.
• Green colored pavement has been given interim approval by FHWA for use on bicycle lanes.

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Retroreflectivity
Similar to signs, pavement markings must be retroreflective for
nighttime visibility. Glass beads placed in the marking material provide
this retroreflectivity. Revision 3 of the 2009 MUTCD now provides for
minimum r etroreflectivity, including:
• Maintain retroreflectivity at or above 50 mcd/m2/lx under dry
conditions for longitudinal markings on roadways with speed
limits of 35 mph or greater
• Maintain retroreflectivity at or above 100 mcd/m2/lx under dry conditions for longitudinal
markings on roadways with speed limits of 70 mph or greater.
Raised reflective pavement markers can also be used to create line patterns or supplement traditional
marking materials.

Type Of Material
Pavement marking materials fall into four primary categories:
• Thermoplastic – a heated plastic material that can be sprayed or extruded onto the pavement
surface
• Paint – in recent years, most agencies have used water-based paints because of their
environmental advantages over solvent-based paints
• Epoxy resin paints – a two component paint that can be sprayed onto the roadway surface
• Preformed tapes – often used for transverse markings and symbols, though can also be used for
longitudinal markings.
Each of these has three primary components – the binder (the material that provides thickness to the
markings), the pigment that provides the color, and glass reflective beads, which provide for the
retroreflectivity of the markings.
In addition, raised reflective pavement markers, which are typically plastic markers with prismatic
reflective elements, can be used to supplement the other markings or, if used in patterns, provide the
markings themselves. However, these are typically used only in areas without significant snowfall, as the
markers are often damaged by plowing operations.

Location And Placement

Longitudinal markings include centerlines, lane lines and edge lines.
These lines not only guide the lateral placement of vehicles on the
roadway, but also provide drivers with advance visibility of upcoming
changes in the roadway alignment and cross section.
The MUTCD requires centerline markings on all paved urban arterials
and collectors that have a traveled way of 20 feet (6.1 m) or more and
an ADT of 6,000 vehicles per day or more. Centerline markings are also required for all paved two-way
roads with 3 or more lanes for moving motor vehicle traffic. On two-lane roads with a marked centerline,
no-passing zones must be designated with a solid yellow line. Passing sight distance criteria are contained
in Table 3B-1 of the MUTCD.

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Edge line pavement markings may be used to denote the edges of the roadway. When used on a divided
highway or one-way street, the left edge line is yellow, and the right edge line is white. The MUTCD
requires edge lines for all freeways, expressways, and paved rural arterials with a traveled way of 20 feet
(6.1 m) or more and an ADT of 6,000 vehicles per day or more.
It is sometimes desirable to extend lane lines through an intersection or interchange where the design
complexity (offset, curve, or multiple-turn lanes) or traffic congestion make the driving task unusually
difficult.
Special longitudinal markings include:
• Solid white lines to discourage crossing (e.g., turn lanes, bicycle lanes, etc.)
• Double-broken, yellow lines to denote each lane line that will serve as a dividing line at some time
of the day for reversible lane operation
• Solid yellow plus broken yellow lines denoting each side of a two-way left turn lane.
Transverse markings include stop lines, yield lines, crosswalks, railroad crossing markings, and diagonal
lines used in painted channelization. Stop lines should be used when it is desirable to designate the desired
point at which vehicles are to stop for a STOP sign or signal. They are especially useful when the STOP sign
cannot be located adjacent to the desired stopping location.
Crosswalks both guide pedestrians to the desired crossing location and warn drivers of the potential
presence of pedestrians. Where transverse lines are used to mark a crosswalk, the gap between the lines
should not be less than 6 feet (1.8 m). Distinctive patterns such as diagonal stripes should be reserved for
crosswalks of special concern where added emphasis is needed.
Word messages and symbols should be limited to as few words as possible and never more than three
lines of information. Letters and symbols should be elongated to avoid a distorted appearance when
viewed from the drivers’ perspective. Words and symbols designating mandatory lane usage or
movement prohibitions should only be considered supplemental to standard regulatory signs. The MUTCD
restricts the use of the diamond symbol only to HOV lanes.
Delineators are retroreflective devices mounted at a height of 4 feet (1.2 m) above the roadway edge, at
a constant distance from the edge of roadway, 2 to 8 feet (0.6 to 2.4 m) from the outer edge of the
shoulder. Delineators are generally required continuously along the right side of freeways and
expressways, and along one side of ramps. They may also be used along any type of roadway.

Pattern
Longitudinal lines include four primary configurations:
• A double line indicates maximum or special restrictions,
• A solid line discourages or prohibits crossing (depending on the specific application),
• A broken line indicates a permissive condition, and
• A dotted line provides guidance or warning of a downstream change in lane function.

Surface Versus Inlaid Application

Traditionally, pavement markings have been placed on the surface of the roadway. However, in areas
with high traffic or where there is significant snowplow activity, some agencies are using inlaid markings
on asphalt pavements, which provides for an extended lifespan. The pavement surface where the marking

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is planned is ground to a depth of about 5 mm, and then thermoplastic material is placed to be flush or
slightly higher than the surrounding pavement surface.

Transit, Bicycle, And Pedestrian Considerations

One consideration related to pavement marking materials for bicyclists and pedestrians is the avoidance
of slip hazards; paints and especially thermoplastic can, in certain circumstances, be very slippery and
therefore a hazard. Many agencies include sand or other coarse materials within the marking materials
to provide additional slip resistance.
In a similar concern, the use of raised pavement markers in areas of pedestrian traffic should be minimized
because of the potential for a tripping hazard.

Installation And Removal

The installation of pavement markings is dependent on the material and the type of marking. Longitudinal
lines are typically placed with a truck mounted spray system; transverse lines and symbols often use hand
propelled applicators. Stencils can be used for word legends and symbols. Raised reflective pavement
markers are typically placed by hand and adhered to the pavement using epoxy or bituminous adhesive.
The removal of pavement markings can be accomplished by grinding or water blasting; overlaying an
existing marking with black paint is not allowed. Grinding and water blasting can leave some scarring on
the pavement surface which, depending on lighting conditions, might provide confusing or conflicting
guidance to the driver.

Roadway/Railroad Grade Crossings

The highway-railroad grade crossing is unique in that it constitutes the intersection of two transportation
modes, which differ both in the physical characteristics of their traveled ways and in their operation.
Crashes at highway-railroad grade crossings are rare and relatively random events, averaging 0.025
crashes per public crossing per year. They account for 0.1 percent of total traffic crashes in the United
States each year, although they represent 0.6 percent of the highway fatalities. The annual number of
grade crossing crashes has generally decreased over the years. However, the relatively high severity of
grade crossing crashes demands special attention.
In order to improve safety and efficiency at highway railroad grade
crossings, a wide range of potential improvements may be considered.
These include:
• Upgraded passive or active traffic control devices
• Changes in horizontal and/or vertical alignment of highway
and/or rail line
• Improvements in sight distance
• Crossing surface improvements
• Crossing illumination
• Grade separation
• Closing the crossing

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• Do-nothing
The standards for traffic control systems for highway-railroad grade crossings are set forth in Part 8 of the
MUTCD. These systems can be classified as passive and active, referring to the type of traffic control
devices employed.

Type Of Control
Passive devices include signs and pavement markings
• The standard railroad crossing sign or “crossbuck” is required
on each approach to all crossings (public and private) and is
normally installed on the right side of the roadway.
• A Railroad Advanced Warning Sign shall be used on each
roadway approach in advance of every grade crossing except
on low-volume, low-speed roadways crossing minor spurs or other tracks that are infrequently
used and which are flagged by train crews; in the business districts of urban areas where active
grade crossing traffic control devices are in use; or where physical conditions do not permit even
a partially effective display of the sign.
• STOP or YIELD signs may be used at the discretion of the state or local agency at any crossing with
two or more trains per day (if the crossing does not have active devices). They may also be used
at crossings where an engineering study establishes their need.
• Pavement markings placed in advance of a grade crossing consist of an X, the letters RR, a no-
passing marking (two-lane roads), and transverse lines, and are required on all paved approaches
where there are signals or automatic gates, or where vehicle speeds are 40 mph (65 km/h) or
greater. Dynamic envelope markings, denoting the clearance required for the train overhang
resulting from any combination of loading, lateral motion, or suspension failure, are optional.
Active devices include flashing light signals, bells, and gates.
• The flashing light signal installation displays red signals flashing alternately to indicate the
approach or presence of a train. Where additional emphasis or better visibility is required,
supplemental signals are placed on cantilevers.
• A highway railroad crossing gate is used as a supplement to flashing lights. Such gates are
classified as “traffic gates” in the MUTCD. They are designed to warn, but not primarily to provide
a physical barrier to vehicle and pedestrian traffic when in the lowered position.
In a “four-quadrant” gate installation, gates are placed on both sides of the roadway for each approach.
In order to prevent vehicles from being trapped between the gates, the gates on the far or exit side of the
track(s) are lowered at a later time than those on the near or entrance side. In some cases, detectors are
used to identify vehicles that may be stopped on the tracks, and the far side gates are not lowered until
the vehicles depart the track area.

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Sight Distance
Adequacy of sight distance is critical at passive crossings; however,
even where active devices are present or will be provided, sight
distance is beneficial to confirm the ability to cross the tracks. Three
key sight distance zones are:
• Approach Sight Distance - where the road user becomes aware
of the presence of a crossing ahead.
• Corner Sight Distance - allows an approaching road user the ability to see an approaching train
• Clearing Sight Distance - the visibility available to a road user along the track when stopped ahead
of the crossing

Signal Preemption
Where a signalized highway intersection is close to a railroad crossing and either the crossing is impacted
by queues from the intersection or the intersection is impacted by queues from the crossing, the railroad
signal control equipment and the traffic control signal control equipment should be interconnected, and
the normal operation of the traffic signals controlling the intersection should be preempted to operate in
a special control mode when trains are approaching.
A preemption sequence typically provides for a track clearance phase, where time is provided for vehicles
that may have stopped on the tracks to move forward, and then one or more dwell phases designed to
keep vehicles and pedestrians moving along paths that do not conflict with the track crossing. Upon the
passage of the train, the preemption routine would then advance to selected exit phases, from which the
intersection returns to normal operation.

Queue Management
Queue management can be provided through the use of Pre-Signals and Queue Cutter Signals. Pre-Signals
are used to stop vehicular traffic before the railroad crossing in cases where the queue from a signalized
intersection regularly extends back to the crossing area.
Queue-Cutter Signals are used where the crossing is located farther than 450 to 500 feet (depending on
vehicle lengths) from the highway intersection to reduce preemption times and to hold traffic upstream
from a crossing before a queue caused by a downstream traffic control signal or other roadway congestion
can grow long enough to back up into the crossing. Queue-cutter signal operation may be based on
downstream queue loop detectors, timed operations, or a combination of the two.

Work Zones And Temporary Traffic Control

Part VI of the MUTCD is entitled, “Temporary Traffic Control,” and provides guidance for traffic control
for highway work zones and incident areas. The principal objective of temporary traffic control is safety –
the safety of workers and safety of the road users. Proper traffic control devices and procedures will keep
traffic moving and enable workers to perform their tasks without unnecessary risk or delay.

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Typical problems encountered, which can contribute to road user

confusion and create hazardous situations include:
• Insufficient advance warning – inadequate signing, insufficient
distance in which to respond, unclear instructions.
• Inadequate guidance and delineation - lack of information,
poorly placed devices, conflicts with permanent pavement
markings.
• Unprotected hazards - debris, materials, equipment, and excavations.
• Conflicts created by work activities - workers outside of protected area, equipment operating too
close to the traveled way, traffic control devices obstructing vision.
• Poor housekeeping - debris on roadway, water or mud on pavement, dirty, damaged, or non-
functioning devices.
• Distractions to road users - gawking, unusual devices, operations too close to the traveled way.
• Confusion non-standard devices, too many choices for motorists, improper placement of devices,
too many or too few devices.
• Traffic congestion - backups, delays, driver frustration, and impatience.

Types Of Work Zones

The traffic control zone is the entire section of roadway containing the temporary traffic control devices
associated with a work activity. The zone extends from the first advance warning sign to the last sign or
channelization device. The traffic control zone typically includes:
• Advance warning area. In this area, the road user is given
information about hazards ahead and the actions which must
be taken. The only devices used in this area are signs.
• Transition area. In this area, traffic is channelized from the
normal lanes to the paths required to move through the
activity area.
• Activity area. This is the area where the work takes place. It is composed of:
 Work space. Area set apart for exclusive use by workers, equipment, and material.
 Traffic space. The portion of the roadway in which traffic is routed through the activity
area.
 Buffer space. A buffer space is used as recovery space for errant vehicles. No work activity
should take place in this space. The longitudinal buffer space may be placed in the initial
portion of a closed lane, which precedes the actual work space. The lateral buffer space
may be used to separate the traffic space from the work space or a potentially hazardous
area
 Termination area. The termination area is used at work sites to allow traffic to clear the
activity area and to return to the normal traffic lanes.

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The selection of traffic control procedures and devices is dependent on the following factors:
• Work activity. Work zones are frequently classified according to the type of work that is being
performed. Actually, this has little significance to road users. They are only concerned with the
impact of the work activity on their use of the facility.
• Construction projects commonly require several weeks, months, or even years to complete.
Traffic control procedures must accommodate both daytime and nighttime conditions. A long
duration makes it more attractive to invest in high-type traffic controls and facilities such as
barriers and temporary roadways.
• Maintenance operations are generally accomplished more rapidly, rarely exceeding a few days.
However, some maintenance activities involve extensive work and take on the basic
characteristics of a construction project.
• Utility operations are generally short daytime operations, except under emergency conditions.
Because crew sizes are generally small with only a few vehicles involved, the number and types
of traffic control devices placed in the traffic control zone may be minimal.
• Incidents such as crashes, emergencies and disasters may pose severe and unpredictable
problems. The ability to install proper traffic control may be greatly reduced in an emergency and
any devices on hand may be used for the initial response. If the situation is prolonged, the devices
should be upgraded.
• Work duration is a major factor in the design of the traffic
control zone. Duration is generally classified as:
o Long-term stationary activities are those which occupy a
location more than 3 days.
o Intermediate-term stationary work occupies the location from overnight to 3 days. It may not
be feasible or practical to use devices or procedures that would be desirable for long-term
projects such as altered pavement markings, barriers, and temporary roadways
o Short-term stationary work is daytime work that occupies a site from 1 to 12 hours. Most
maintenance and utility work is short-term stationary work. The crew is present to maintain
and monitor traffic control. Use of flaggers may be appropriate
o Short duration work occupies a location for up to one hour. There are hazards involved in
setting up and taking down traffic controls, and road user exposure time would be
significantly increased as the traffic control is expanded. Simplified traffic control procedures
may therefore be warranted. However, the use of fewer devices should be offset by the use
of other more dominant devices such as special lighting units on work vehicles.
o Mobile work moves intermittently or continuously along the roadway. It often involves
frequent, short stops as long as 15 minutes. For some continuously moving operations, where
traffic volumes are light and sight distance is good, a well-marked work vehicle may suffice.
Where feasible, warning signs should be placed along the roadway and moved periodically as
work progresses. Vehicles may be equipped with flashing vehicle lights, truck-mounted
attenuators, and appropriate signs, and flaggers and/or shadow vehicles may be useful. Safety
should not be compromised by using fewer devices simply because the operation will move
frequently.

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• Type of facility is also a primary factor in the selection of appropriate traffic control devices.
o Freeways and expressways require the highest type of traffic control because of high speeds,
multiple lanes, and often high volumes of traffic. Longer distances are needed to provide
adequate response times at high speeds. More signs may be needed to get messages to road
users traveling in interior lanes.
o Rural two-lane highways are characterized by lower volumes, but high speeds.
o Urban arterial streets generally have lower speeds but may still require a significant amount
of traffic control because of high volumes. Close intersection spacing may necessitate reduced
device spacing. The needs of pedestrians and cyclists may have to be addressed.
o Local streets typically have modest speeds and volumes. The number of signs and sign spacing
may be further reduced. In some cases, a single advance warning sign may be sufficient.
• Location of work sites within the right-of-way also influences the selection of traffic control
procedures and devices. As a general rule, the closer the work is to traffic, the more control
devices are needed.
The following principles provide a guiding philosophy of good traffic control for work zones.
• Traffic safety should be an integral and high-priority element of
every project, from planning through design and construction.
Work should be conducted with the safety of road users and
workers in mind at all times.
• Traffic movement should be inhibited as little as practicable.
Traffic control should be designed with the expectation that
drivers will reduce their speeds only if they clearly perceive a need to, and reduced speed zoning
should be avoided as much as possible. The traffic control plan should be designed so that
vehicles can reasonably safely travel through the work zone with a speed limit reduction of no
more than 10 mph (20 km/h). Frequent and/or abrupt changes in geometrics should also be
avoided. Roadway occupancy should be minimized, and where practicable should be scheduled
during off-peak or nighttime hours.
• Drivers, bicyclists, and pedestrians should be guided in a clear and positive manner. Adequate
warning, delineation, and channelization devices should be provided which are effective under
varying conditions of light and weather.
• To ensure acceptable levels of operation, routine inspection of traffic control elements should be
performed during both daylight and at nighttime. Individuals who are trained in the principles of
safe traffic control should be assigned responsibility for safety at work sites.
• Maintenance of roadside safety requires attention during the
life of the work site because of the potential increase in
hazards. It is desirable to provide an unencumbered roadside
recovery area. Signs and channelization devices should yield
when struck by errant vehicles. Equipment and materials
should not be stored or parked in a buffer space or clear zone.

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• Each person whose actions affect traffic control zone safety should receive training appropriate
to the job decisions each is required to make.
• Good public relations should be maintained by keeping road users, nearby property owners and
businesses, emergency service providers, and railroad and transit operators well informed, and
were needed, their needs accommodated.
Traffic control devices used in work zones include signs, pavement markings, channelization devices, and
other devices. Part VI of the MUTCD contains specific requirements for the design, color, size, and shape
of the traffic control devices used in temporary traffic control zones.

Signing, Markings, Taper Lengths, And Channelizing Devices

Signs provide information to road users regarding the situation ahead
and actions which must be taken. There are three types of signs -
regulatory, warning, and guide signs. Several factors to be considered
in applying signs in a work zone, including:
• Target value can be enhanced by placing signs where they
stand alone and contrast with their background. Target value
can also be enhanced by using larger sign sizes and placing
flags or flashing lights adjacent to the sign panel. Warning and guide signs have either orange or
florescent orange backgrounds to identify them as specifically related to the work zone.
Florescent pink has been adopted as a color for signs in incident management zones.
• Priority value is achieved when the sign is placed where it does not compete for the motorists’
attention. Priority value can be increased by avoiding unnecessary signs and removing or covering
signs that are not applicable.
• Legibility is achieved through the use of adequate size sign panels and lettering on the panel. It is
enhanced through periodic cleaning and replacement when the sign face has been damaged or
defaced.
• Retroreflectorization or illumination is required for all signs that are used at night.
Arrow displays may be used for stationary or mobile lane closures. For a stationary lane closure, the arrow
display should be located on the shoulder at the beginning of the taper.
Channelization devices are used to warn drivers of hazards created by the work activities and to guide and
direct drivers safely past the hazards. Because channelizing devices are potential obstacles, they shall be
crashworthy and should always be preceded by one or more warning signs advising road users of the
existence of the work zone. Channelizing devices should be constructed and ballasted to perform in a
predictable manner when struck by a vehicle. If struck, they should yield or break away, and fragments or
other debris from the device should not penetrate the passenger compartment or be a potential hazard
to workers or pedestrians. Channelizing devices include:
• Cones
• Tubular Markers
• Vertical Panels

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• Drums
• Barricades
When used to close a lane or shift traffic laterally on the roadway,
channelization devices should be arranged in tapers of adequate
length. The following equations can be used to determine taper
length:

L = WS2/60 (U.S. units) or L = WS2/155 (metric units)

For speeds of 40 mph (65 km/h) or less, and

L = W x S (U.S. units) or L = 0.625 x W x S (metric units)

For speeds of 45 mph (70 km/h) or more.
A minimum taper length of L should be used for merging tapers, and a minimum taper length of ½ L should
be used for shifting tapers. Shoulder closure tapers may be 1/3 L.
Lighting devices are often used to supplement channelization and
warning devices to attract the attention of road users, to identify
hazards, and to delineate the travel path.
Portable Barriers may be used to provide a physical device which
vehicles cannot penetrate under normal speeds and impact angles.
They may be constructed of concrete, steel, or any material that will
prevent vehicle penetration. There are four major applications of portable barriers:
• Temporarily separate two-way traffic
• Prevent road users from penetrating into an especially hazardous area such as an excavation
• Provide positive protection for workers or pedestrians
• Protect the components of the highway facility itself, such as a temporary bridge pier.
A barrier should only be installed if it reduces the severity of potential crashes.
Other devices that may be useful for work zones include:
• Truck-mounted attenuators, or crash cushions, can be attached to the rear of trucks used in or
adjacent to high-speed traveled lanes, especially on short duration or mobile operations.
• Rumble strips are transverse strips of rough textured surface on the pavement, used to alert
drivers of unusual or unexpected conditions, or to draw the drivers' attention to a traffic control
device.

Motorist Information (e.g., Communication)

Portable changeable message signs (PCMS) have the flexibility to display a variety of messages. They are
most useful where the message may need to be varied in response to changing traffic or work site
conditions and for emergency situations.
Highway Advisory Radio (HAR) systems can provide an audio message with greater detail than what is
possible through PCMS applications. Road users must actively change their radio channel to listen to the
HAR message, so capture rates are much lower than PCMS.

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Connected vehicle applications will provide greater opportunity for motorist information as that
technology matures.

Queue Management (e.g., Detours) and Roadway Capacity

Construction projects often create bottlenecks – areas of reduced capacity that can result in the
development of queues when the demand levels exceed capacity. Extended queues, besides creating
extended delays for road users, can also generate a hazardous condition for drivers approaching the work
zone and encountering the end of the queue.
Queues can be managed by reducing the demand through the reduced capacity work zone. Detours can
be provided to maintain an acceptable level of capacity; detour planning is an important part of the
Transportation Management Plan. In addition, restricting lane closure or other capacity reducing
activities to times of the day and days of the week when the demands are lower can help manage queues.
Public information, through press releases and announcements to the media, can also get the word to
road users to select alternate routes.
Detours are also effective where commercial vehicles might need to follow a different route from
passenger vehicles because of bridge, weight, clearance, or geometric restrictions. Also, vehicles carrying
hazardous materials might need to follow a different route from other vehicles.

Flagging Operations
Flaggers may be useful in guiding traffic safely through a work area and in protecting the public and
workers. Functions to be performed in a work zone for which flaggers may be necessary include:
• Alternately stop and release traffic when both directions of traffic use one lane.
• Stop all traffic for short periods of time to accommodate equipment movements, placing
apparatus over the roadway, etc.
• Maintain traffic through a work area at reduced speeds.
• Look out for and help protect the work crew.

Temporary Traffic Signals

Temporary traffic signals are sometimes used in work zones at locations like temporary haul road
crossings; temporary one-way operations along a one-lane, two-way highway; and temporary one-way
operations on bridges, reversible lanes, and intersections. Temporary traffic control signals should only
be used in situations where temporary traffic control signals are preferable to other means of traffic
control, such as changing the work staging or work zone size to eliminate one-way vehicular traffic
movements, using flaggers to control one-way or crossing movements, using STOP or YIELD signs, and
using warning devices alone. When used, temporary traffic signals must comply with the applicable
provisions of Part 4 of the MUTCD.

Potentially Hazardous Conditions

Road user and worker safety and accessibility in work zones should be an integral and high-priority
element of every project from planning through design and construction. Similarly, maintenance and
utility work should be planned and conducted with the safety and accessibility of all motorists, bicyclists,
pedestrians (including those with disabilities), and workers being considered at all times. If the work zone
includes a grade crossing, early coordination with the railroad company or light rail transit agency should
take place.

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Temporary Traffic Control Plans

Adequate maintenance of the traffic control zone over the life of the
project is essential to the safety of road users and workers.
Deficiencies that degrade the effectiveness of the traffic control
devices include dirt; damage from rough handling, traffic impacts, and
vandalism; displacement and damage due to construction activities;
weather; and malfunctions and burnouts. Routine maintenance
inspection of the traffic control zone is necessary to identify and
correct such deficiencies and to service the devices.
Field review should ensure that there is driver compliance with work zone traffic control. Where problems
are observed, the traffic control should be revised until compliance is obtained.
The needs and control of all road users (motorists, bicyclists, and pedestrians) including persons with
disabilities through a work zone shall be an essential part of planning, design, operation, and maintenance
of work area traffic control. Pedestrians should not be led into conflicts with work site vehicles,
equipment, or operations, or conflicts with roadway traffic moving through or around the work site.
Pedestrians should be provided with a reasonably safe, convenient, and accessible path that replicates as
nearly as practical the most desirable characteristics of the existing sidewalks.
Individual channelizing devices, tape or rope used to connect individual devices, other discontinuous
barriers and devices, and pavement markings are not detectable by persons with visual disabilities and
are incapable of providing detectable path guidance on temporary or realigned sidewalks or other
pedestrian facilities. When it is determined that a facility should be accessible to and detectable by
pedestrians with visual disabilities, a continuously detectable edging should be provided throughout the
length of the facility such that it can be followed by pedestrians using long canes for guidance
Part VI of the MUTCD contains a series of “Typical Application” drawings which provide guidance in the
concepts and principles of traffic control for work zones. These typical applications are not intended to be
applied rigidly. Rather, they provide guidance which may require modification in actual field applications.

Transportation Management Plans

A Transportation Management Plan (TMP) lays out a set of
coordinated transportation management strategies and describes
how they will be used to manage the work zone impacts of a road
project. The scope, content, and level of detail of a TMP may vary
based on the State or local transportation agency's work zone policy,
and the anticipated work zone impacts of the project. In some cases, a
regional TMP may be developed to better mitigate the combined
effects of several projects occurring within a corridor or roadway network.
Although TMPs are required for all federal-aid projects, those projects deemed as "significant" require a
comprehensive TMP consisting of the following:
• A temporary traffic control (TTC) plan to address traffic safety and control needs throughout the
work zone.
• A traffic operations (TO) component to address sustained operations and management of the
work zone impact area (which can extend a substantial distance away from the actual project
location).

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• A public information (PI) and outreach component to address communication needs with the
public and concerned stakeholders.

Speed Management
Speed is a contributing factor in about one quarter of all fatal work zone crashes. There are a variety of
methods and technologies that can be used to help manage and enforce speed limits in work zones,
including the use of law enforcement officers, automated enforcement (depending on regional
regulations), speed advisory systems, and variable speed limit (VSL) systems.
Many agencies utilize off-duty police officers in marked vehicles to be clearly visible speed deterrents
within work zones and to provide active enforcement when necessary. Automated enforcement systems,
primarily photo-radar speed enforcement, are options in those states and jurisdictions that allow them.
Many times, drivers don’t realize their own speeds; radar speed displays (speed feedback signs) have been
successful in alerting drivers that their speeds are excessive. And, the use of variable speed limits, slowing
drivers while construction activities are under way or when work zone queues are forming, can help
management speeds along the corridor.

Road User Guidance

As many road users may be encountering work zones for the first time, proper guidance is critical.

Signage And Markings

Signs in work zones have the same three categories as all road user signs: regulatory, warning, and guide.
Warning signs in work zones shall have a black legend and border on an orange background, except for
the Grade Crossing Advance Warning (W10-1) sign which shall have a black legend and border on a yellow
background, and except for signs that are required or recommended to have fluorescent yellow-green
backgrounds; regulatory and guide signs normally follow their standard colors. Where the color orange
is required, the fluorescent orange color may also be used to provide higher conspicuity, especially during
twilight .
Pavement markings should be provided in a work area, to the extent practical, comparable to the markings
normally maintained along adjacent roadways. The MUTCD includes the following provisions:
• In long-term stationary work areas, markings shall match the markings in place at both ends of
the project.
• Markings shall be in place along any surfaced detour or temporary roadway before it is opened
to traffic.
• In any work area where it is not practical to provide a clear path by markings, appropriate warning
signs, channelizing devices, and delineation shall be used to indicate the required vehicle paths.
In long-term projects, pavement markings which are no longer appropriate shall be removed or
obliterated.
Temporary markings are those pavement markings or devices that are placed within work zones to
provide road users with a clearly defined path of travel through the zone when the permanent markings
are either removed or obliterated during the work activities. All temporary broken-line pavement
markings shall use the same cycle length as permanent markings and shall have line segments that are at
least 2 feet (0.6 m) long. Unless justified based on engineering judgment, temporary pavement markings

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should not remain in place for more than 14 days after the application of the pavement surface treatment
or the construction of the final pavement surface on new roadways or over existing pavements.

Advanced Warning
The advance warning area is the section of highway where road users are informed about the upcoming
work zone or incident area. Typical distances for placement of advance warning signs on freeways and
expressways should be longer because drivers are conditioned to uninterrupted flow. Therefore, the
advance warning sign placement should extend on these facilities as far as 1/2 mile or more. On urban
streets, the effective placement of the first warning sign in feet should range from 4 to 8 times the speed
limit in mph, with the high end of the range being used when speeds are relatively high. When a single
advance warning sign is used (in cases such as low-speed residential streets), the advance warning area
can be as short as 100 feet. Since rural highways are normally characterized by higher speeds, the
effective placement of the first warning sign in feet should be substantially longer—from 8 to 12 times
the speed limit in mph.

Changeable Message Signs

Portable changeable message signs have a wide variety of applications in work zones including roadway,
lane, or ramp closures; incident management; width restriction information; speed control or reductions;
advisories on work scheduling; road user management and diversion; warning of adverse conditions or
special events; and other operational control. The primary purpose of portable changeable message signs
in work zones is to advise the road user of unexpected situations. Portable changeable message signs are
particularly useful as they are capable of:
• Conveying complex messages,
• Displaying real time information about conditions ahead, and
• Providing information to assist road users in making decisions prior to the point where actions
must be taken.

Human Factors
Much of the placement and application of traffic control devices is based upon the assumption that road
users will be prudent and reasonable in their actions, being observant, noticing and understanding the
devices, and taking the appropriate actions. Many drivers become familiar with their local roadways and,
unfortunately, do not expect the unexpected. Work zones and similar locations utilizing temporary traffic
control present the unexpected. Accordingly, special care is needed in applying temporary traffic control
techniques.

Highway Advisory Radios

A Travelers’ Information Station, also called Highway Advisory Radio, can be beneficial in some projects.
Travelers' Information Stations operate in the AM Broadcast Band (530 kHz - 1700 kHz) and are limited to
a 10-watt transmitter output power, an antenna height no greater than 15 meters (49.2 feet), and a
coverage radius of 3 km. FCC licensing is required and typically only available to governmental entities.

Traveler Information Systems

Advanced traveler information systems (ATIS) provide static and real-time information on traffic
conditions, schedules, road and weather conditions, special events, and tourist information.

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Traveler information systems include techniques to provide traveler information to individuals. They
include both pre-trip and en-route information. Concepts include:
• Pre-trip
o Commercial radio and television
o Telephone call-in systems (511)
o Ride matching and reservations
o The internet
o Kiosks
o Personal communications devices (PDAs)

• En-Route
o Variable message signs (VMS)
o Highway advisory radio (HAR)
o Transit stop displays
o MAYDAY systems
o Hazard warning systems
o In-vehicle navigation
o Dynamic route guidance

Transportation Systems Management And Operations (TSM&O)

Applications
TSM&O incorporates an integrated program to optimize the
performance of existing infrastructure through the implementation of
specific systems, such as Intelligent Transportation Systems (ITS), and
services that pre serve capacity and improve reliability and safety. The
TSM&O activities focus on a set of well-known strategies such as
incident management, traffic signal timing, ramp metering, road
weather management, and others.
Intelligent Transportation Systems (ITS) include the application of advanced and emerging technologies
in fields such as information processing, communications, control, and electronics to surface
transportation needs.
ITS concepts can be grouped in four areas:
• Transportation Systems Management
• Traveler Information Distribution
• Commercial Vehicle Operations
• Intelligent Vehicle and Connected Vehicle Systems

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Transportation systems management techniques encompass all

concepts used to manage transportation better – all modes, urban and
rural areas, freeways and surface streets. This category includes the
following:
• Arterial Management
• Freeway Management
• Incident Management
• Emergency Management
• Weather and Road Condition Warning Systems
• Railroad Crossing Systems
• Parking Management
• Electronic Toll and Traffic Management
• Transit Management
• Electronic Fare Payment Systems
Commercial vehicle operations involve applying information and communications technologies to
enhance the safety and economy of commercial trucks and buses. Concepts included in commercial
vehicle information systems and networks include:
• Commercial vehicle electronic clearance
• Automated roadside inspection stations
• Onboard safety monitoring technologies
• Commercial vehicle administrative processes
• Freight mobility systems
Intelligent vehicle and connected vehicle systems include the use of
driver assistance and vehicle control intervention systems to enhance
safety and efficiency of vehicle operations. They include the following:
• Rear-end and frontal collision avoidance
• Longitudinal and lateral control
• Lane departure avoidance
• Lane change and merge collision avoidance
• Visual enhancement systems
• Obstacle and pedestrian detection

Traffic Signal Coordination

Coordination is a tool to provide the ability to synchronize multiple intersections to enhance the operation
of one or more directional movements in a system. Examples include arterial streets, downtown
networks, and closely spaced intersections such as diamond interchanges. A well-timed, coordinated

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system permits continuous movement along an arterial or throughout a network of major streets with
minimum stops and delays, which reduces fuel consumption and improves air quality.

Traffic Management Centers

Traffic management centers (TMCs) serve as the control point for an area’s arterial and highway network.
The TMC monitors traffic signals, intersections, and roads and proactively deploys traffic management
strategies to reduce congestion and coordinate state and local authorities during special events,
emergencies, or daily stop-and-go traffic. Operators monitor closed circuit television cameras and alert
the proper authorities and approaching drivers about problem areas, reducing crashes and saving drivers
time, money, and wasted fuel.

Video Surveillance
The placement of video cameras along roadways or at key intersections provides for the monitoring of
traffic conditions without having to be physically in the field. Cameras typically have pan-tilt-zoom
capabilities to allow focusing on items of interest; for example, knowing the extent of damage following
a crash can provide valuable advance information to emergency responders. Cameras are best placed at
higher elevations, such as signal pole tops, to provide the greatest coverage.
Privacy is a major concern in the placement and use of cameras. Policies and/or hardware or software
restraints should be in place to eliminate viewing of sensitive areas such as private residences. Many
agencies do not record the video streams due to public records
concerns or storage space requirements.

Real-Time Traveler Information

Providing information to road users in real time is a major component
of traffic management. In the example of an incident that blocks a
major freeway, the rapid dissemination of information about the
blockage and alternate routes will help users minimize their delays while also helping workers at the
incident by minimizing traffic impacts at the site. Real time information can be provided though
changeable message signs, telephone and web-based systems, in-vehicle systems, and media broadcasts.

System Software
Software is required to operate the various components of the traffic management system – to collect
and aggregate data from various sources, to adjust signal timing, to control pan-tilt-zoom cameras, and
to update messages on changeable message signs. In the past, each of these subsystems were operated
independently with vendor-supplied proprietary software; in modern systems, these subsystems are all
integrated into a single system to speed response times and simplify efforts for the operator.

Communication Media Between Signal Devices And Control Center

The control center must be able to communicate with the field located traffic management devices such
as signal controllers, changeable message signs, and closed-circuit cameras. The communications media
must be able to provide sufficient bandwidth for the connected device and must also be secure.
The favored medium is fiber optic cable based, due to its very high bandwidth capabilities, strong security,
and virtually no interference from electrical interference or lightning. However, construction costs can be
significant, particularly if the fiber optic cabling is to be placed underground in conduit.

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Cellular based communications have been used both for isolated locations and some areawide
deployments; depending on the system configuration, leased cellular connections may be economically
superior to the costs of physical fiber optic infrastructure and its ongoing maintenance.
Wireless interconnection is often used for “last mile” connections; for example, to extend
communications from a signalized intersection with a fiber optic connection to a nearby signal not on the
fiber optic network.
Twisted-pair cabling, as used in the telephone industry, typically does not have the bandwidth needed for
quality color CCTV communications but may be appliable for interconnecting local signal controllers.

Center-To-Center Communication (e.g., Law Enforcement, Media,

Subcenters)
Many agencies provide center-to-center communications for the sharing of information and CCTV video
streams. These connections allow law enforcement and emergency services dispatch centers to be able
to see and understand what the traffic management center is handling during an incident. And, television
stations desiring access to CCTV images for their news broadcasts may also request connections. These
connections may be established through the existing communications network or through leased lines.

Dynamic And Changeable Message Signs

Changeable message signs include any sign that can alter its display, including internally illuminated signs
that can blank out a message. Dynamic message signs are a subset of changeable message signs and refer
to computer driven electronic signs (typically LED technology) that can provide messages that include
either text or graphical symbols. Both provide motorist information and are controlled from a centralized
traffic management center.

Ramp Metering
Ramp metering is used to control the flow of traffic upstream of points of recurring congestion to limit
the density of flow to a level below the point of maximum density for peak flow. This is typically done by
metering the flow on entrance ramps with traffic signals. Algorithms have been developed which use data
on mainline flow to establish metering rates limiting the rate at which ramp vehicles can merge with the
freeway flow. A typical ramp metering signal layout includes two-lens (red/green) or three-lens
(red/yellow/green) signal heads, controller cabinet, and upstream and downstream vehicle detectors.
Ramp control is being used successfully in many cities and has been proven to reduce freeway congestion
and improve safety. Engineering studies are needed to determine the feasibility of installing metering
devices at specific locations based on evaluations of freeway congestion, potential congestion reduction,
ramp geometry (particularly storage space beyond the ramp signal), and opportunities for motorists to
divert to other routes.

Detection
Detection technologies used in traffic management systems are essentially the same as those used at
signalized intersections, and include inductive loops, video, and microwave sensors. Along freeways,
these are often placed at regular intervals, such as half mile spacing, to identify variations in traffic flow,
volumes, and speeds, and to provide input into travel time estimates.

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Managed Lanes (e.g., HOV, Truck, Bus, Toll)

Managed lanes are highway facilities or a set of lanes where operational strategies are proactively
implemented and managed in response to changing conditions. The managed lane concept may vary in
specific definition from one agency to the next, but all the definitions have common elements:
• The managed lane concept is typically a "freeway-within-a-freeway" where a set of lanes within
the freeway cross section is separated from the general-purpose lanes.
• The facility incorporates a high degree of operational flexibility so that over time operations can
be actively managed to respond to growth and changing needs.
• The operation of and demand on the facility is managed using a combination of tools and
techniques to continuously achieve an optimal condition, such as free-flow speeds.
• The principal management strategies can be categorized into three groups: pricing, vehicle
eligibility, and access control.
Examples of operating managed lane projects include high-occupancy vehicle (HOV) lanes, value priced
lanes, high-occupancy toll (HOT) lanes, or exclusive or special use lanes. Each of these concepts offers
unique benefits; therefore, careful consideration is given to project goals and objectives in choosing an
appropriate lane management strategy or combination of strategies. Project goals may include increasing
transit use, providing choices to the traveler, or generating revenue.

Traffic Incident Management

Traffic incident management (TIM) provides an opportunity to enhance the operations of existing freeway
facilities with minimal capital investment. It addresses one of the most common sources of congestion
and provides significant return on investment. Traffic incident management provides a pre- planned,
coordinated approach to detecting and managing the response to incidents as quickly and safely as
possible, and returning the facility to normal operations.
Traffic incidents impact the transportation system by reducing capacity, increasing congestion-related
delay, and reducing safety. In terms of capacity, it is important to note that the percentage capacity
reduction is much greater than the percentage of lanes blocked by an incident. For example, if one out of
two freeway lanes is blocked by a crash, two-thirds of the roadway capacity is lost. This is due to traffic
from the closed lanes merging into the open lanes, the “gawker effect,” and the resulting upstream
congestion. This may be aggravated by emergency vehicles moving
through traffic or impacting the remaining lanes for specific
operations.
Delay resulting from incidents accounts for 50 percent or more of
congestion in metropolitan areas. In areas that do not experience
recurring or peak-hour delays, such as rural highways, incidents may
account for as much as 100 percent of delay. The impact of residual
delay following an incident is significantly higher than the delay associated with the incident itself. It has
been observed that in urbanized areas there can be as much as 5 minutes of residual delay for every 1
minute of incident impact.
If half or more of urban delay is attributable to incidents and, according to the 2021 Urban Mobility
Scorecard, the cost of congestion in 471 urban areas was $190 billion, traffic incident management
provides an opportunity to reduce at least half of that cost. Congestion is not limited to only peak periods.

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Approximately 41 percent of total delay occurs in the midday and overnight (outside of the peak hours)
times of day when travelers and shippers expect free-flow travel.
Improved safety is another important benefit of traffic incident management. Nationally, it has been
found that about 20 percent of incidents are the result of another incident. These secondary incidents
may include rear-end crashes, shoulder collisions, and responder incidents. These secondary crashes are
often more severe than the original incident. Those most at risk are victims of the initial incident and
emergency responders. In a recent year, 25 firefighters were killed in motor vehicle crashes, 6 after being
struck by a motor vehicle. Similarly, nearly 40 percent of all law enforcement officers killed in the line of
duty died in traffic. In addition, incident-related delay impacts the ability of emergency responders to
respond to the scene and to transport patients from the scene.
Traffic incident management provides an opportunity to enhance safety, reduce system delays, and
increase capacity. From a system management and operations perspective, and to address user and
customer service expectations, possibly the greatest benefit of traffic incident management is the ability
to increase system reliability by reducing the impact of non- recurring congestion.

Implementing TIM Programs

Key components of traffic incident management programs include a variety of specific tools, clearly
defined roles, guidelines for coordination with other agencies, training for field and response personnel,
and performance measures that can be used to determine program effectiveness
Potential components of a TIM program include operational, and programmatic applications that can be
used to enhance incident detection and verification, response, clearance, recovery and scene
management as well as traveler information. Each of these aspects of traffic incident management is
important to reducing the extent and duration of impact on the roadway.
• Video surveillance is one of the most effective tools for incident detection and verification. It
offers monitoring capabilities that can quickly identify an incident and provide specific
information to responders on the nature of the incident. It can also provide additional traveler
information if a feed is provided to a website or other broadcast media. Video surveillance also
supports management and operations of recurring congestion on a daily basis.
• Automated detection can include a variety of technologies used to detect changes in the speed
and/or density of traffic on the roadway. This can then be used to notify operators of congestion
and potential incidents.
• Cell phones are probably the most widely used device to notify responders and operators of
crashes or other incidents. Their use can be enhanced through public education, dedicated phone
numbers, and improved service.
• Spotters or probes are trained members of the public or agencies who travel on a roadway on a
regular basis or have a view of the facility from their work or home. They can report incidents or
other non-recurring congestion.
• Automated vehicle identifiers can be used to monitor the speed of traffic on facilities regularly
traveled by transit service or other operators using AVI.
• Weather stations can be used to detect weather-related incidents.
• Patrols, whether law enforcement or courtesy patrols can be used to detect and respond to
incidents. These can be implemented during peak periods or on a 24-hour basis.

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• Call boxes provide motorists with the ability to report incidents, particularly in areas with limited
services or limited cell phone access.
• Management centers, either traffic operations or emergency management centers, provide
information to responders and the public and help orchestrate response, clearance, and recovery,
including the implementation of alternative routes and traveler information.
• Incident response teams can be established to ensure rapid, coordinated response to traffic
incidents.
• Pre-planned diversion routes, or alternate routes, can be developed to assist in clearing traffic
from closed facilities and maintaining traffic flow through the system.
• Crash investigations sites provide a location for law enforcement to complete their paperwork
and to relocate vehicles involved in minor incidents. This helps restore travel lanes to traffic more
quickly.
• Quick clearance or move-it laws require drivers involved in minor crashes to move their vehicles
from the roadway as quickly as possible.
• Towing contracts - Many law enforcement agencies have call lists or contracts with towing
companies to aid in clearance. These can be expanded to include enhanced capabilities to address
a wide range of towing needs or to provide patrol functions on the highway.
• Courtesy patrols that patrol predetermined sections of roadway can help move stalled or
abandoned vehicles, change flat tires, or provide fuel to move vehicles out of travel lanes and off
highway shoulders.
• Changeable message signs – One of the best ways to provide information to travelers on the
roadway is through variable or dynamic message signs. These should be located to support
alternate route decision points.
• Highway advisory radios can provide more information than signs, including anticipated duration
and alternate route directions. These can be combined with roadside signs or VMS to notify
drivers to tune to the HAR frequency.
• Broadcast media, TV and radio, can be an excellent source for travel information. Building
partnerships and developing information feeds can increase the effectiveness of this outlet.
• New and evolving technology such as in-vehicle warning and route information during incidents,
automated weather detection and warning messages, and changeable speed limits all provide
opportunities to inform and warn motorists of incidents and manage travel.

School Zone Applications

Traffic flow around schools is often a concern. Young students may not be aware of the dangers of being
around moving vehicles, and parents, not comfortable with allowing their children to walk to and from
school, will drive them to and from the school. Recent research indicates that 20 to 25 percent of morning
traffic is due to parents driving their children to school. As a result, traffic congestion has increased around
schools, prompting even more parents to drive their children to school.
There is a need to provide options that allow all children, including those with disabilities, to walk and
bicycle to school safely. Children, in general, engage in less physical activity, which contributes to the

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prevalence of childhood obesity. Providing safe opportunities to walk to school will also help to reduce
traffic congestion around the schools.

Safe School Routes

Schools can create a Safe Routes to School (SRTS) program that integrates health, fitness, traffic relief,
environmental awareness, and safety under one program. Successful SRTS programs in the United States
have incorporated one or more of the following approaches:
• The Encouragement Approach uses events and contests to entice students to try walking and
biking.
• The Education Approach teaches students important safety
skills and launches driver safety campaigns.
• The Engineering Approach focuses on creating physical
improvements to the infrastructure surrounding the school,
reducing speeds and establishing safer crosswalks and
pathways.
• The Enforcement Approach uses local law enforcement to ensure drivers obey traffic laws.
The National Highway Traffic Safety Administration has spearheaded the SRTS effort and has developed
supporting materials for interested schools.

Speed Management (e.g., Enforcement, Traffic Calming)

Key to the SRTS program is managing speeds within the vicinity of the school or near school walk routes,
thus minimizing the possibility of a serious injury crash. Tools used for speed management on all roads
can be applied to school locations as well; traffic calming strategies coupled with enforcement are major
components.
Pedestrian safety depends upon public understanding of accepted methods for efficient traffic control.
This principle is especially important in the control of pedestrians, bicycles, and other vehicles in the
vicinity of schools. Neither pedestrians on their way to or from school nor other road users can be
expected to move safely in school areas unless they understand both the need for traffic controls and how
these controls function for their benefit.

Traffic Control (e.g., Signs, Pavement Markings, Beacons, Crossing

Guards)
Regardless of the school location, the best way to achieve effective traffic control is through the uniform
application of realistic policies, practices, and standards developed through engineering judgment or
studies. The MUTCD provides detailed information on traffic control devices used in school zones,
including special school related signs, pavement markings, and beacons.
Adult school crossing guards play an important role in the lives of children who walk or bicycle to school.
They help children safely cross the street at key locations. They also remind drivers of the presence of
pedestrians. The presence of adult crossing guards can lead to more parents feeling comfortable about
their children walking or bicycling to school.

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Pick-Up, Drop-Off, And On-Site Circulation

Traffic activity on school grounds as well as activity in the area surrounding the school must be considered
in the safety analyses. The queuing of motor vehicles to drop off and pick up children is a particular
concern because of the possibility of conflicts. An orderly process – a single line of vehicles, immediately
adjacent to the sidewalk – is highly desirable. The off-site drop off and pick up of children by parents
wanting to bypass the queue adds to the confusion of the area and has a significant impact on safety.

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REFERENCES
Questions for the certification examination are derived and/or documented from a number of
professional sources. Some of the most frequently cited references are:
Title: Highway Capacity Manual, 7th Edition: A Guide for Multimodal Mobility Analysis
Author(s): Transportation Research Board Inc.
Publisher: TRB, ISBN: 978-0-309-08766-7
ITE Publication Number: LP-674C
Publication Date: 2022

Title: Manual of Transportation Engineering Studies, 2nd Edition

Author(s): Edited by H. Douglas Robertson
Publisher: ITE, ISBN: 978-1-933452-53-1
ITE Publication Number: TB-012A
Publication Date: 2010

Title: Manual on Uniform Traffic Control Devices, 2009 Edition

Author(s): FHWA/ITE/ATSSA/AASHTO
Publisher: FHWA/ITE/ATSSA/AASHTO, ISBN: 978-1-56051-473-2
ITE Publication Number: MUTCD-10
Publication Date: 2009

Title: A Policy on Geometric Design of Highways and Streets, 7th Edition

Author(s): AASHTO
Publisher: AASHTO, ISBN: 978-1-56051-676-7
Publication Date: 2018

Title: Traffic Engineering Handbook, 7th Edition

Author(s): ITE, Brian Wolshon and Anurag Pande
Publisher: Wiley, ISBN: 978-1-118-76230-1
ITE Publication Number: LP-691
Publication Date: 2016

Title: Traffic Safety Toolbox: A Primer on Traffic Safety

Author(s): ITE
Publisher: ITE, ISBN: 0-935403-43-4
ITE Publication Number: LP-279A
Publication Date: 1999

Title: Transportation Planning Handbook, 4th Edition

Author(s): Edited by Michael D. Meyer
Publisher: ITE, ISBN: 978-1-118-76235-6
ITE Publication Number: LP-695
Publication Date: 2016

Title: Highway Safety Manual

Author(s): AASHTO
Publisher: AASHTO, ISBN: 978-1-56051-477-0
ITE Publication Number: LP-672
Publication Date: 2010

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Title: Signal Timing Manual - NCHRP Report 812, Second Edition

Author(s): Tom Urbanik, Alison Tanaka, et al.
Publisher: TRB, National Cooperative Highway Research Program
Publication Date: 2015

Website References
Connected Vehicles, https://www.pcb.its.dot.gov/eprimer/module13.aspx

Freight and Commercial Vehicle ITS, https://www.pcb.its.dot.gov/eprimer/module6.aspx#is

USDOT, ATDM Program Brief: An Introduction to Active Transportation and Demand Management.
http://www.ops.fhwa.dot.gov/publications/fhwahop12032/fhwahop12032.pdf

In addition to these professional references, a candidate may find it advantageous to review a general
traffic or transportation engineering text. Among the excellent texts currently available, the following
was frequently cited in question documentation:

Title: Fundamentals of Traffic Engineering, 16th Edition (Currently not Available)

Author(s): Homburger, W., et al.
Publisher: University of California
Publication Date: 2007

In addition, the following references relate to this current module:

Manual of Uniform Traffic Control Devices for Canada, Transportation Association of Canada, 2021.
https://www.tac-atc.ca/en/publications-and-resources/mutcdc
Standard Highway Signs, Federal Highway Administration, 2004 and 2012 Supplement.
https://mutcd.fhwa.dot.gov/ser-shs_millennium.htm
Rodegerdts, L.A., et.al., Signalized Intersection Information Guide, Federal Highway Administration Report
No. FHWA-HRT-04-091, Washington, DC, 2004.
A Toolbox for Alleviating Traffic Congestion, Institute of Transportation Engineers, 1997.
Traffic Control Devices Handbook, Institute of Transportation Engineers, 2014.

Module 4 © 2022 Institute of Transportation Engineers

Traffic Control Devices 4-50 Student Supplement