Understanding Travel Demand Modeling: A Comprehensive Overview
Explore the essential components of travel demand modeling, including trip generation, distribution, mode choice, and assignment. Learn about trip production, attraction modeling, and practical applications through in-class activities and examples.
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Travel Demand Modeling 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 Mode Choice Zone Trip Zone Trip Mode 1 Mode 2 Attractions Productions 1 2 3 1 2 3 Traffic Assignment Trip Distribution 1 2 3 Route 1 Route 2 Route 3 1 2 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 In TAZ 235, you have following socioeconomic data; Households (HH): 23,000 Average Annual Income per HH: $30,000 Average cars per HH: 1.4 Average number of people per HH: 2.1 Average number of workers per HH: 1.4 Total Office Space: 2,000,000 ft^2 Total Retail Space: 5,000,000 ft^2 Estimate zone productions and attractions? ??????????????? = 0.3 + 0.82 ??????? 0.0024 ???? 0.041???? 4.7? 06 ?????? 9
Trip Attraction Models 10
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 Trip generation process usually results in non- equal numbers of total production & attraction Trip productions considered more accurate (based on survey data) Trip attractions modified so that total trip attractions are equal to total trip productions Adjustment factor: fa = Pi/ Ai, i zone Adjusted attractions for each zone: Aadji = Ai*fa 13
In-class Activity 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
