1. Chapter 4. Modeling Transportation Demand and Supply
We cover only 4.1 in this class. By the end of this section the student will be able to:
List the four steps of transportation demand analysis
List the four steps of travel demand forecasting modeling process
Identify, quantify, and discuss the relationship between land use and transportation activity
Calculate estimates of the number of trips “generated” by a particular land use
Explain the purpose of Traffic Analysis Zone (TAZs)
Explain two-way relationship between land use and travel
Topics of Chapter 4 and Chapter 5 will be extensively covered in CEEn 565 Urban Transportation Planning taught by Dr. Schultz. (It will be offered in the fall semester every year.) If you are planning to take CEEn 565 as a technical elective, keep this textbook because Dr. Schultz covers the entire materials of Chapters 4 and 5 of this textbook as part of his CEEn 565.
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2. Mythaca’s congestion problem now (SR361)
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3. Mythaca’s congestion problem (SR361): one solution (bypass) and change in traffic
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4. 4.1.1 Anticipating future network needs
Transportation planning is a process that involves:
the analysis of current travel patterns,
the forecasting of future travel patterns (Transportation Demand Analysis),
the proposal of transportation infrastructure and services, and
the evaluation of proposed alternative projects to be considered by decision makers for implementation
The result is a plan – A set of improvements to be considered by decision makers.
Basic concepts of travel demand modeling:
Travel demand is a derived demand
Travel patterns are influenced by land use
Individuals’ decision making habits influence travel demand
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5. General 4 steps of transportation demand analysis
Data collection (population, land use, etc.)
Economic activity (employment, sales volume, income, etc.), land use (type, intensity), travel characteristics (trip and traveler profile), and transportation facilities (capacity, travel speed, etc.), population and demography, Origin-destination trip data.
Analysis of existing conditions and calibration
Analyze the data collected in the data collection stage. You may build mathematical models to describe the existing conditions and then use the relationships you have found in the existing parameters to forecast future values.
Forecast of future travel demand
4-step transportation demand forecasting modeling process
Analysis of the results
Analyze what you get from the 4-step demand forecasting process
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6. 4-step transportation demand forecasting modeling process (and this is what covered in this section.)
Preparation: population and economic analysis and land use analysis
Trip generation
Determines how many trips each activity (center) (residential area, commercial area, etc) will produce or attract
Trip distribution
Determines the origin or destination of trips that are generated at a given activity
Modal split
Determines which mode of transportation will be used to make the trip
Traffic assignment
Determines which route on the transportation network will be used when making the trip
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7. Travel demand forecasting modeling process (4-step model)
Should I make a trip?
What should be my destination?
What mode of transportation should I use?
What route or path should I take?
p.4.5 Think About It: Think back to the last four or five trips you made. Did you ask yourself any or all of the four questions above? If so, in what order did you consider the questions.
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8. Analysis zones for transportation study (TAZ)
First, we need to divide the study area into smaller zones of (hopefully) uniform land use
Dense area, in terms of population and businesses, has more zones. Zones usually get larger in less dense areas.
More reasonable to use TAZ than a site-by-site analysis when regional planning is done.
Standard trip generation methods:
site-based
zone-based
household-based
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9. Link-node map for highway system
Link-node maps are the starting point for the 4-step transportation demand forecasting process
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10. Graphical way of understanding the 4-step demand forecasting process
200 trips from zone 46 to zone 29
1000 trips attracted to zone 29: employment center
1000 trips generated in zone 46: residential area zone
70% this route (140 trips)
Auto total: 95% (190 trips)
Public transit: 5% (10 trips)
25% this route (50 trips)
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11. Transportation facilities
4.1.2 Land use and tripmaking
Finding how many trips are generated from a zone is the first step of urban transportation demand modeling. At a macro level, it is a region wide demand forecasting and at a micro level the public agency wants to know how many trips a development in a land can produce – like how many trips a planned Walmart might produce.
Tripmakers
Transportation facilities
Land use
MAG’s 2040 Transportation Plan
Demand Forecasting
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12. Estimating the number of trips generated:
CEEn 565 deals with various methods to do this step, but in this lecture, we use charts found in the ITE Trip Generation Handbook to show you how to get quickly ballpark estimates – and of course there are a few pitfalls...
(Walk through Example 4.1.)
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