CE416 Lecture 01: Introduction
CE416
Geometric Design of Highways
Fall 2015
Instructor: Dr. Mohamed Imbarek Esekbi
Department of Civil Engineering
E-mail: Prof.Esekbi@ outlook.com
Lectures: Group Monday/Thursday Room
1 8:00 – 9:30 C7
2 11:00 – 12:30 C2
Office Hours: 9:45 – 10:45, Monday & Thursday or by appointment
Course Outline
Course Topics
1. Introduction and roadway function
2. Design controls
3. Sight distance
4. Horizontal alignment
5. Vertical alignment
6. Cross-sections
7. Intersection and Interchanges
8. Parking Facilities
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CE416 Lecture 01: Introduction
Texts and References Course Outline
Text Book:
A Policy on Geometric Design of Highways and Streets (AASHTO )
Principles of Highway Engineering and Traffic Analysis, 5th Edition
Fred L. Mannering and Scott S. Washburn
Course Notes, Prof. Mohamed Esekbi
References:
Libyan Manual for Geometric Design of Highways
Design Criteria for Infrastructure Projects-Rev 03 (HIB)
Website: https://www.facebook.com/groups/ce416
Texts&Ref
https://www.facebook.com/groups/ce416
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CE416 Lecture 01: Introduction
Course Outline
Grading system:
Home Works 20%
Midterm 20%
Attendance & Quizzes 10%
Final Exam 50%
100%
Introduction & Course Overview
• Course Overview – Q&A’s:
- why is this course offered?
- what pre-knowledge are needed?
- About the textbook, are there any alternatives?
- what will we learn from this course?
- how is this course organized?
- what you should be able to do after the course?
- how can this course assist in my professional career?
- how can this course assist in my academic career?
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CE416 Lecture 01: Introduction
Introduction & Course Overview
why is this course offered?
Geometric Design of Highways: An important component of
Highway Engineering
CE314 Highway Engineering
CE416 Geometric Design of Highways
Highway Engineering CE414 Pavement Design
CE516 Advanced Highway Materials
CE517 Advanced Pavement Design
Geometric Design of Highways
Highway, Geometry, Design
What pre-knowledge are needed?
CE311- Transportation Engineering
Why the text book is so expensive? Are there any alternatives?
The “Green book” is regarded as the “bible” of Highway Design
• Most state DOTs (Department of Transportation) adopt the
principles of Green book in the “state highway design manual”,
some states use Green Book directly
• Almost all text books available are developed based on the
Green book
• However, the Green Book tells you about the “PRINCIPLES”, you
need also learn the “hands-on” things – the purpose of the
homework and projects
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CE416 Lecture 01: Introduction
What will we learn from the course?
Principles of highway and street design
Highway classification
Design speed
Design vehicles
Sight distance
Highway Alignment (Horizontal, Vertical curves)
Cross-section
Intersections
Parking lots
What should I be able to after the course?
Conduct preliminary design of rural, urban highway &
streets including route selection, alignment design, and
intersection design
How will my performance be evaluated?
Attendance, home works, quizzes, midterm and final exams.
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CE416 Lecture 01: Introduction
how can this course assist in my professional career?
Consulting firms – Contractors
Traffic engineering division
Department of transportation – highway design division
County/city traffic engineering office
how can this course assist in my academic career?
Highway geometric design and safety
Traffic engineering
Driver characteristic study
Design standards
Highway Geometric Design
Introduction
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CE416 Lecture 01: Introduction
Definition of Geometric Design :
• geometric design of highways deals with the dimensions
and layout of visible features of the highway.
• Geometric design fulfills the requirements of the driver
and the vehicle, such as comfort, efficiency and safety.
• Proper geometric design will help in the reduction of
accidents and their severity.
Goals of geometric design
• Maximize the comfort, safety and economy of facilities.
• Provide efficiency in traffic operation.
• Provide maximum safety at reasonable cost.
• Minimize the environmental impacts.
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CE416 Lecture 01: Introduction
Functional Classification
of Highways
Shara 11th June
Algharbi Road
University
Abouslem Road
street
Airport Shargya
Road street
2nd Ring
Road
Sample of the street map of Tripoli
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CE416 Lecture 01: Introduction
Highway Classification System
• The classification of highways into different
operational systems, functional classes, or
geometric types is needed for communication
among engineers, administrators, and the
general public.
• Various classification schemes have been
applied for distinct purposes in different rural
and urban regions.
Highway Classification
System
• Classification of highways by design types based on the major geometric
features (e.g., freeways, conventional streets, and highways) is the most
helpful approach for highway location and design procedures.
• Classification by route numbering (e.g., Numbers, Letters, and colors) is
the most helpful approach for traffic operations.
• Administrative classification (e.g., National Highway System or Non-
National Highway System) is used to denote the levels of government
responsible for and the method of financing highway facilities.
• Functional classification, the grouping of highways by the character of
service they provide, was developed for transportation planning
purposes.
• Comprehensive transportation planning, which is an integral part of
total economic and social development, uses functional classification as
an important planning tool.
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CE416 Lecture 01: Introduction
THE CONCEPT OF FUNCTIONAL CLASSIFICATION
Hierarchies of Movements and Components
• The functional classification of a highway or street is primarily
based on motor vehicle travel characteristics and the degree of
access provided to adjacent properties.
• Motor vehicle travel involves a series of distinct travel
movements. The six recognizable stages in most trips include:
1. main movement
2. transition
3. distribution
4. collection
5. access
6. termination.
Figure shows a hypothetical highway trip
using a freeway, where the main
movement of vehicles is uninterrupted,
high-speed flow.
When approaching destinations
from the freeway, vehicles reduce
speed on freeway ramps, which act
as transition roadways.
The vehicles then enter moderate-
speed arterials (distributor facilities)
that bring them nearer to the vicinity
of their destination neighborhoods.
They next enter collector roads that
penetrate neighborhoods.
The vehicles finally enter local access roads that provide direct
approaches to individual residences or other terminations.
At their destinations, the vehicles are parked at an appropriate terminal
facility.
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CE416 Lecture 01: Introduction
• Each of the six stages of this
hypothetical trip is handled by
a separate facility designed
specifically for its function.
• Because the movement
hierarchy is based on the total
amount of traffic volume,
freeway travel is generally the
highest level in the movement
hierarchy, below that is
distributor arterial travel, and
lowest in the movement
hierarchy is travel on collectors
and local access routes.
Functional Relationships
• Functional classification is applied to group streets
and highways according to the character of service
they are intended to provide.
• This classification recognizes that individual roads
and streets do not serve travel independently.
• Most travel involves movement through road
networks and can be classified by its relationship to
such networks in logical and consistent categories.
• Functional classification of roads and streets is also
consistent with categorization of travel.
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CE416 Lecture 01: Introduction
Highway Functions
In Figure A, lines of travel desire are straight
lines connecting trip origins and destinations
(circles).
• The widths of the lines indicate the relative
amounts of travel desire.
• The sizes of the circles indicate the relative trip-
generating and attracting power of the places
shown.
Because it is impractical to provide
direct-line connections for every desire
line, trips should be channelized on a
limited road network in the manner
shown in Figure B.
• Heavy travel movements are served
directly or nearly so
• Smaller movements are channeled into
somewhat indirect paths.
The facilities in Figure are labeled local access, collector, and arterial,
which are terms that describe their functional relationships.
Highway Functions
The arterial highways generally
provide direct service between
cities and larger towns that
generate and attract a large
proportion of the relatively longer
trips.
Roads of the intermediate
functional category (collectors)
serve small towns directly,
City Town
connecting them to the arterial
Village
network.
Arterials
local roads serving individual Collectors
farms and other rural land uses Locals
or distribute traffic to these local
roads from the arterials.
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CE416 Lecture 01: Introduction
Arterials
Highway Functions
Schematic Illustration
of a Portion of a
Collectors
Suburban Street
Network
Locals
Highway Functions
Mobility Vs Accessibility Mobility Freeways
Mobility: Arterials
The ability to move goods and Mobility Higher degrees of Mobility
Low degree of access
passengers to their destination.
(in a reasonable time)
Collectors
Accessibility: Balance between Arterials
and Collectors
the ability to reach desired
destination,
Access Locals
Lower degrees of mobility,
High degree of access
Local Streets
Accessibility
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CE416 Lecture 01: Introduction
Functional System Services Provided
Arterial Provides the highest level of service at the
greatest speed for the longest uninterrupted
distance, with some degree of access control.
Collector Provides a less highly developed level of
service at a lower speed for shorter distances
by collecting traffic from local roads and
connecting them with arterials.
Local Consists of all roads not defined as arterials or
collectors; primarily provides access to land
with little or no through movement.
Highway Classification in Libya
28
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CE416 Lecture 01: Introduction
Role of Functional Classification
in Design Process
Design Speed Horizontal / Vertical
Alignment
Functional
Classification
Cross Section
Thank you
Next Lecture : Design Factors
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