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Four-Step Model

The document outlines the transportation planning process, focusing on travel demand forecasting and the traditional four-step model: trip generation, trip distribution, modal split, and traffic assignment. It details how trip generation assesses the number of trips based on various factors, while trip distribution allocates these trips between zones using methods like the gravity model. Additionally, it discusses modal split and route assignment to optimize transportation network usage.

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venom34545
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40 views36 pages

Four-Step Model

The document outlines the transportation planning process, focusing on travel demand forecasting and the traditional four-step model: trip generation, trip distribution, modal split, and traffic assignment. It details how trip generation assesses the number of trips based on various factors, while trip distribution allocates these trips between zones using methods like the gravity model. Additionally, it discusses modal split and route assignment to optimize transportation network usage.

Uploaded by

venom34545
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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CONTRIBUTORS

OF
TRANSPORTATION
PLANNING
PROCESS
TRANSPORTATION PLANNING GOALS
TRAVEL DEMAND FORECASTING
• Number of vehicles expected to travel between a
particular origin and destination via particular
route and mode of travel oven a given time period
• Required for:
❑New construction
❑Expansion/improvement of the existing facilities
FOUR DECISIONS ARE THE BASIS OF THE
TRADITIONAL TRAVEL DEMAND MODEL
•CHOICE AND REASON TO TRAVEL
•DESTINATION OF TRAVEL
•MODE BY WHICH TO TRAVEL
•ROUTE ON WHICH TO TRAVEL
TRIP GENERATION
The four-step transportation model is a traditional model for
transportation planning and forecasting that consists of the following
steps:
1. Trip generation- Determines the number of trips that are generated
and attracted to a specific zone. Factors that influence trip
generation include income, vehicle ownership, employment, and
land use.
2. Trip distribution - Distributes trips between zones, taking into
account constraints like distance.
3. Modal split - Determines the mode of transportation used for a trip.
4. Traffic assignment - Assigns trips to the transportation network,
taking into account that users want to minimize their travel time.
1. TRIP GENERATION
2. TRIP DISTRIBUTION
3. MODAL SPLIT
4. ROUTE ASSIGNMENT
1. TRIP GENERATION
1. TRIP RATE METHOD

ANS: 5189 TRIPS


2. CROSS CLASSIFICATION
3. MULTIPLE LINEAR REGRESSION ANALYSIS
BEFORE THE HOUSEHOLD MOVES: 0.535 TRIPS
AFTER THE HOUSEHOLD MOVES: 0.985 TRIPS
O-D MATRIX
2. T R I P D I S T R I B U T I O N

•Process by which trips generated in one


zone are allocated to other zones
•Uses different methods but gravity model
is most popular
Growth Factor Methods
• Assume that in the future trip making pattern will remain
substantially the same as today but that the volume of trips will
increase according to the growth of the generating and attracting
zones
• Often adequate for small towns where considerable changes in
land use and external factors are not expected
SYNTHETIC METHODS
SAMPLE PROBLEM
New attraction for each zone at Kth iteration
3. MODAL SPLIT
MNL MODEL

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