Chapter 4Chapter 4 11
Chapter 4. Modeling Transportation Chapter 4. Modeling Transportation Demand and SupplyDemand and Supply
1.1. List the four steps of transportation demand analysisList the four steps of transportation demand analysis2.2. List the four steps of travel demand forecasting modeling List the four steps of travel demand forecasting modeling
processprocess3.3. Identify, quantify, and discuss the relationship between Identify, quantify, and discuss the relationship between
land use and transportation activityland use and transportation activity4.4. Calculate estimates of the number of trips “generated” by a Calculate estimates of the number of trips “generated” by a
particular land useparticular land use5.5. Explain the purpose of Traffic Analysis Zone (TAZs)Explain the purpose of Traffic Analysis Zone (TAZs)6.6. Explain two-way relationship between land use and travelExplain two-way relationship between land use and travel
We cover only 4.1 in this class. By the end of this section the student will be able to:
Topics of Chapter 4 and Chapter 5 will be 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 keep this textbook because Dr. Schultz covers the entire materials of Chapters 4 and 5 of this textbook as part of his course.
33Chapter 4Chapter 4
Mythaca’s Mythaca’s congestion congestion
problemproblem(SR361): (SR361):
one one solution solution (bypass) (bypass)
and and change in change in
traffictraffic
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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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55Chapter 4Chapter 4
Data collection Data collection (population, land (population, land use, etc.)use, etc.)
Economic activity (employment, sales volume, income, Economic activity (employment, sales volume, income, etc.), land use (type, intensity), travel characteristics (trip etc.), land use (type, intensity), travel characteristics (trip and traveler profile), and transportation facilities (capacity, and traveler profile), and transportation facilities (capacity, travel speed, etc.), population and demography, Origin-travel speed, etc.), population and demography, Origin-destination trip data.destination trip data.
Analysis of existing Analysis of existing conditions and conditions and calibrationcalibration
Analyze the data collected in the data collection stage. You Analyze the data collected in the data collection stage. You may build mathematical models to describe the existing may build mathematical models to describe the existing conditions and then use the relationships you have found conditions and then use the relationships you have found in the existing parameters to forecast future values.in the existing parameters to forecast future values.
Forecast of future Forecast of future travel demandtravel demand
4-step 4-step transportation demand forecasting modeling transportation demand forecasting modeling processprocess
Analysis of the Analysis of the resultsresults
Analyze what you get from the 4-step demand forecasting Analyze what you get from the 4-step demand forecasting processprocess
General 4 steps of transportation demand analysis
66Chapter 4Chapter 4
4-step transportation 4-step transportation demand forecasting demand forecasting modeling processmodeling process
Preparation: population and economic analysis and Preparation: population and economic analysis and land use analysisland use analysis
Trip generationTrip generation Determines how many trips each activity (center) Determines how many trips each activity (center) (residential area, commercial area, etc) will produce or (residential area, commercial area, etc) will produce or attractattract
Trip Trip distributiondistribution
Determines the origin or destination of trips that are Determines the origin or destination of trips that are generated at a given activitygenerated at a given activity
Modal splitModal split Determines which mode of transportation will be used Determines which mode of transportation will be used to make the tripto make the trip
Traffic Traffic assignmentassignment
Determines which route on the transportation network Determines which route on the transportation network will be used when making the tripwill be used when making the trip
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Travel demand Travel demand forecasting forecasting
modeling process modeling process (4-step model)(4-step model)
1. Should I make a trip?
2. What should be my destination?
3. What mode of transportation should I use?
4. What route or path should I take?
p.187 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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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
Land useTransportation facilities
MAG’s 2040 Transportation PlanDemand Forecasting
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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 a few pitfalls...
(Walk through Example 4.1.)
1010Chapter 4Chapter 4
Analysis zones for transportation study (TAZ), Analysis zones for transportation study (TAZ), p.194-196p.194-196First, 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 thana site-by-site analysis when regional planning is done.
Standard trip generation methods:• site-based• zone-based• household-based
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Link-node map for highway systemLink-node map for highway system
Link-node maps are the starting point for the 4-step transportation demand forecasting process
1212Chapter 4Chapter 4
Graphical way of understanding the 4-step Graphical way of understanding the 4-step demand forecasting processdemand forecasting process
1000 trips generated in zone 46: residential area zone
1000 trips attracted to zone 29: employment center
200 trips from zone 46 to zone 29
Auto total: 95%(190 trips)
Public transit: 5%(10 trips)
70% this route (140 trips)
25% this route (50 trips)