TRANSPORTATION ENGINEERING
AND PLANNING
(110 401367)
SPRING 2019-2020
Lecture. No. 6
Travel demand forecasting
Dr. Hamza Alkuime
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Topic 2 : Transportation planning
References
■ Nicholas Garber and Lester Hoel ,Traffic & Highway
Engineering, 5th Edition.. Cengage Learning, 2015
Chapter 12 : Forecasting Travel Demand
Section 11.4
■ Daniel J Findley, Christopher Cunningham, Bastian J.
Schroeder, Thomas H. Brown, Highway Engineering:
Planning, Design, and Operations, 2016, Elsevier
Chapter 2.2: Planning concepts and Four-step process overiew
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Topic 2 : Transportation planning
References
■ Nicholas Garber and Lester Hoel ,Principles of Highway
engineering and traffic analysis, 5th Edition, 2012
Chapter 8 : Travel Demand and traffic forecasting
■ Partha chakroborty and Animesh Das, Principles of
transportation engineering, 2012,
Chapter 9: Transportation demand analysis
■ Dušan Teodorović and Milan Janić,Transportation
engineering theory, practice and modeling , 2017,
Chapter 8: Transportation demand analysis
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Review
Planning-Level Demand Estimation
■ The traffic that this land use will add to the highway and transit
facility can be determined using the four-step process
■ The urban traffic forecasting process involves
Tip generation
Trip distribution
Modal split
Network assignment
■ The travel forecasting process is used to estimate the traffic
volume volumes on each link of the system
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Review
Defining the Study Area
■It is usually necessary to delineate the study area
boundaries and to further subdivide the area into
traffic analysis zones (TAZ) for data tabulation
Review
The process involves :
1. Defining the Study Area
2. Data Collection
3. Population and Economic Data
4. Transportation Inventories
5. Information Systems
6. Travel Surveys
7. Calibration
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Review
Highway planning study
■ The process involves developing a computerized
network of the existing street and highway system is
produced
■ The network consists of a series of
links
Nodes
Centroids
External stations
Review
Traffic Analysis
Zones (TAZ)
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Review
Highway planning study
■ Links
a portion of the highway system that can be described by its capacity, lane width, and speed
■ Nodes
The end point of a link and represents an intersection or location where a link changes
direction, capacity, width, or speed
■ Centroids
The location within a zone where trips are considered to begin and end
■ External stations
are those roadways where traffic is likely to enter or exit the study area
It established at the study area boundary
Travel demand
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Planning definitions and terms
■ Capacity
A transportation facility’s ability to accommodate a moving stream of people or vehicles in a
given time period
■ Land use
Refers to the manner in which portions of land or the structures on them are used (or
designated for use in a plan), such as commercial, residential, retail, industrial, etc
■ Mode:
A specific form of transportation, such as automobile, subway, bus, rail, air, bicycle, or foot.
■ Performance measures:
Indicators of how well the transportation system is performing with regard to such measures
as average speed, reliability f travel, and accident rates. Used as feedback in the decision-
making process
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Nature and analysis of transportation demand
■ Transportation demand is a derived demand
– That is, a person generally demand to be transported not because
he/she just wants to move, but because he/she wants to achieve
some other purpose such as reaching school, university, or office.
■Travel demand is primarily generated by the
populations need to work, socialize, stud, etc.
– Therefore, it is not surprising that two of the major aspects in
travel demand analysis are land use and trip-purpose
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Nature and analysis of transportation demand
Land use
■ Land use refers to the manner in which portions of land
or the structures on them are used (or designated for
use in a plan), such as commercial, residential, retail,
industrial, etc
■ Land use affects the transportation demand through
generation and distribution of trips
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Nature and analysis of transportation demand
Relationship between land-use and transportation demand
■ It is not necessarily a
one-way effect but
rather a part of a
cycle
In this cycle in which
land-use changes the
transportation needs
which in turn change
land-use
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Nature and analysis of transportation demand
Definition of a trip
■Trip
Is an out-way movement from a point of origin to a point
of destination.
The basic quantity in travel demand
It materializes after the trip-maker makes certain decisions
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Nature and analysis of transportation demand
Trip-purpose
■Home-based trips
If either origin or
destination of a trip is the
home of the trip maker
■Non home-based trips
Any trip that is not a
home-based trip
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Nature and analysis of transportation demand
Trip-purpose
■ Home-based work (HBW)
If the trip is between the
home and the work of the trip
make
■ Home-based other (HBO)
If the trip is between the
home and destination except
the work of the trip maker
■ Non-home based (NHB)
Any trip is not HBW or NBO
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Nature and analysis of transportation demand
Trip types
■ Trip production
All the trips of
home based
The origin of the
non home-based
trips
■ Trip attraction
Trips do not
classify as trip
production
Image source: https://www.civil.iitb.ac.in/~vmtom/1100_LnTse/203_lnTse/plain/
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Nature and analysis of transportation demand
Trip-purpose
■Travel demand behaviors changes with the trip-
purpose
Work trips
Recreation trips
Shopping trips
■The analysis of travel demand is done separately
for different trip-purposes
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Nature and analysis of transportation demand
Trip-purpose
■ Work trips
Limited number of decisions are available
A person does not necessarily decide every time whether to go to work or
not
Generally fixed location and time
The choice of rout and mode of travel are not daily decisions
■ Recreation trips
A large number of decisions are available
To go or not
Where, when, and how to go
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Trip-maker travel decisions
■ This decisions can be
broadly classified
into:
The decision to travel
The decision on the
choice of destination
The decision on the
choice of mode
The decision on the
choice of route
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Trip-maker travel decisions
Assumptions of non-sequential decision making
Usually the sequential
demand analysis is
used to determine the
travel demands, even
thought this assumption
may be debatable
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Travel demand forecasting
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Forecasting travel demand
Travel demand definition
■It is the number of persons or vehicles per
unit time that can be expected to travel on a
given segment of a transportation system
under a set of given land-use, socioeconomic,
and environmental conditions
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Sequential demand
analysis
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Sequential demand analysis
The analysis procedure
1. The entire study area is divided into various zones based on
land-use
2. The total number of trips generated in the zone are estimated
using trip generation models
3. The output of the trip-generation models are used to
determine the number of trips between all zone pars using the
trip- distribution models
4. The relative shares of the generated trips for the different
modes are estimated using the mode-choice models
5. The traffic –assignment models are used to estimate the
volume on each link of the network
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