Travel Demand Modeling 4 step models 1 Trip

4 -step Models 1. Trip Generation: How many people travel? 2. Trip Distribution: What

Examples of 4 -steps Models Trip Generation Zone Trip Productions Zone 1 1 2

In-class activity TAZ 1 TAZ 6 Home Work A worker leaves TAZ 1 in

Step 1: Trip Generation • Trip Production Modeling Techniques: • • Regression Techniques Cross

In-class activity Estimate Zone Productions 9

Cross Classification Models Step 1: create matrix that shows number & percentage of HHs

Balancing Productions and Attractions Ø Trip generation process usually results in nonequal numbers of

In-class Activity Ø Balance trip production and attractions for the following two senecios. Scenario

Sources of Uncertainties in Predicting Number of Trips • The model development • The

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Travel Demand Modeling (4 -step models) 1. Trip Generation 2. Trip Distribution 3. Mode Choice 4. Trip Assignment 1

4 -step Models 1. Trip Generation: How many people travel? 2. Trip Distribution: What are the travel patterns for the study area? 3. Mode Choice: What travel modes are used? 4. Trip Assignment: What trip paths will be followed through the transportation network? 2

Examples of 4 -steps Models Trip Generation Zone Trip Productions Zone 1 1 2 2 3 3 Trip Attractions Trip Distribution 1 1 2 3 Mode Choice Mode 1 Mode 2 Traffic Assignment Route 1 Route 2 Route 3 3

Define Trip Production and Attraction 5

In-class activity TAZ 1 TAZ 6 Home Work A worker leaves TAZ 1 in the morning to go to work in TAZ 6. In the evening, same worker comes back TAZ 1. How many trips?

In-class Activity Example 7

Step 1: Trip Generation • Trip Production Modeling Techniques: • • Regression Techniques Cross Classification (or category) Analysis. • Trip attraction models 8

In-class activity Estimate Zone Productions 9

Trip Attraction Models 10

In-class Activity 11

Cross Classification Models Step 1: create matrix that shows number & percentage of HHs as function of HH attributes (most common size, income, auto ownership, # of workers) Step 2: create matrix that shows average number of trips per HH versus HH attributes Step 3: Use O-D data from survey to determine percentage of trips by trip purpose as function of HH attributes Step 4: calculate total number of trips per day generated in zone 12

Balancing Productions and Attractions Ø Trip generation process usually results in nonequal numbers of total production & attraction Ø Trip productions considered more accurate (based on survey data) Ø Trip attractions modified so that total trip attractions are equal to total trip productions Ø Adjustment factor: fa = ΣPi/ ΣAi, i – zone Ø Adjusted attractions for each zone: Aadji = Ai*fa 13

In-class Activity Ø Balance trip production and attractions for the following two senecios. Scenario 2 Scenario 1 Unbalanced NHB Trips NHB Productions NHB Attractions 1 240 100 2 400 200 3 160 300 Total 800 600 Source: Traffic & Highway Engineering, Garber & Hoel 14

Sources of Uncertainties in Predicting Number of Trips • The model development • The prediction of future demographics • The use of the model for predicting the future 15