GEOG 111/211A Transportation Planning UTPS (Review from last time) Urban Transportation Planning System –Also known as the Four - Step Process –A methodology to model traffic on a network –Developed in 1962 (Chicago) Four Steps: –Trip Generation Estimate Person Trips for each TAZ –Trip Distribution Distribute Person Trips from TAZ to TAZ –Mode Choice Convert Person Trips to Vehicle Trips –Traffic Assignment Assign Vehicles to the Network Oct/Nov 2004

GEOG 111/211A Transportation Planning Survey Data – interviews of persons about their behavior Models of behavior – extract key aspects to capture most variation Use models – incorporate models into a computerized map If no survey available? Discuss options in class!

GEOG 111/211A Transportation Planning The Four Steps: Trip Generation= Estimate Person Trips for each TAZ Trip Distribution = Distribute Person Trips from TAZ to TAZ Mode Choice = Convert Person Trips to Vehicle Trips Traffic Assignment = Assign Vehicles to the Network Pre 4-step = Land Use and Demographics? Post 4-step = Emissions, Traffic Simulation, Link by Link Evaluation

GEOG 111/211A Transportation Planning Key Concepts of UTPS TAZ: Traffic Analysis Zone –A TAZ is an arbitrary subdivision of the study area –TAZs are used in trip generation and trip distribution –TAZs may be any shape or size, but US Census Blocks, Block Groups, and Tracts are often used BlockBlock GroupTract i.e., a city block

GEOG 111/211A Transportation Planning Key Concepts of UTPS Centroid –Every TAZ (Gate and Internal Zone) has a centroid, usually placed roughly at the geographic center of the TAZ –All trips to or from a TAZ are assumed to start or end at the centroid Discussion –Why do we use TAZs and centroids to model trips?

GEOG 111/211A Transportation Planning Key Concepts of UTPS Gate TAZs –TAZs placed outside the Study Area where major roads cross the boundaries of the study area –Used to model External Trips (i.e., trips with an origin or destination or both outside the study area) –Gate TAZs represent all areas outside of the study area (Study Area) Gate TAZ Network

GEOG 111/211A Transportation Planning Gate TAZ Centroid

GEOG 111/211A Transportation Planning Every zone is a node (the centroid) with an identifier and type

GEOG 111/211A Transportation Planning Trip Generation Additional suggested reading material: Ortuzar & Willumsen, third edition, Chapter 4.

GEOG 111/211A Transportation Planning Trip Generation Objectives Estimate amount of trip making going out of a TAZ Estimate amount of trip making going into a TAZ Account for differences among TAZs due to person and household characteristics Account for differences among TAZs due to business (establishments) characteristics Develop functions to predict future amount of trip making

GEOG 111/211A Transportation Planning Trip Generation Usual Process Collect Data, usually by Surveys and Census –Sociodemographic Data and Travel Behavior Data Create Trip Generation Models Estimate the number of Productions and Attractions for each TAZ, by Trip Purpose Balance Productions and Attractions for each Trip Purpose –Total number of Productions and Attractions must be equal for each Trip Purpose

GEOG 111/211A Transportation Planning Trip Generation Models Regression Models –Explanatory Variables are used to predict trip generation rates, usually by Multiple Regression Trip Rate Analysis –Average trip generation rates are associated with different trip generators or land uses Cross - Classification / Category Analysis –Average trip generation rates are associated with different trip generators or land uses as a function of generator or land use attributes Models may be TAZ, Household, or Person - Based

GEOG 111/211A Transportation Planning Usual Unit of Analysis TAZ - zonal rates (Number of trips as a function of a zone’s population characteristics) Household rates (Number of trips as a function of household characteristics) Person rates (Number of trips as a function of person characteristics) NEW (PennState Research)! Multilevel rates (Number of trips as a function of person & household & TAZ characteristics)

GEOG 111/211A Transportation Planning Units and Models TAZ-based models = productions and attractions converted to origins and destinations Household and/or person - based models = origins and destinations Establishment - based = attractions need to convert to destinations

GEOG 111/211A Transportation Planning Common Trip Definitions in CE422 Trip: a one - way movement from one place to another HB = Home Based: a trip where the home of the traveler is either the origin or the destination of the trip HBW = Home Based Work: trips between home and work HBNW = Home Based Non-Work: trips between home and shopping, also called HBS (Home Based Shopping) HBO = Home Based Other: trips between home and a non - work / shopping location NHB = Non Home Based: trips where neither end of the trip is the home of the traveler

GEOG 111/211A Transportation Planning Related Definitions Home Work School 1.Home-based school trip 2.NonHome-based work trip 3. Home-based work trip 1+2+3=Tour or Trip Chain (home-based)

GEOG 111/211A Transportation Planning Productions - Attractions Residential Area Non-Residential Area Non-Residential Area Non-Residential Area Production Attraction Production All Home - Based Trips Non - Home - Based Trips = Origin = Destination See also OW-p. 124

GEOG 111/211A Transportation Planning Trip Balancing Methods Hold Productions Constant –Attractions are multiplied by the ratio of the sum of non- gate productions to the sum of non - gate attractions –Most common form of trip balancing Hold Attractions Constant –Productions are multiplied by the ratio of the sum of non- gate productions to the sum of non - gate attractions Hold Neither Productions or Attractions Constant –Not used very often Note: Gate Productions and Attractions are not included in this balancing process

GEOG 111/211A Transportation Planning Examples Day/ - discussion of time-of-day issueshttp://tmip.fhwa.dot.gov/clearinghouse/docs/Time- Day/ (this is the metropolitan plan where models are used) All sites verified October 2004

GEOG 111/211A Transportation Planning Gate Trip Estimation Gate Trips Must be Modeled Separately –Gates have specific traffic volumes associated with them –Gates do not have sociodemographic data –Gates may represent trips with extremely variable trip lengths Gate Trip Modeling –Correlate percentages of traffic volumes to different trip purposes (e.g., X% * Total daily volume observed = trips for commuting)

GEOG 111/211A Transportation Planning ITE Trip Generation Manual Trip Rate Analysis Model –Univariate regression for trip generation –Primarily for businesses (attraction rates) –Explanatory variables are usually number of employees or square footage –Models developed using data from national averages and numerous studies from around the US Copies of the ITE Trip Generation Manual may be Found in the Hammond and PTI Libraries

GEOG 111/211A Transportation Planning

TAZ Issues Data availability limited by privacy issues Larger TAZs, with complete data, are no longer necessarily homogeneous Model accuracy decreases with larger TAZs TAZ Scale Modeling Accuracy Data Availability Block GoodPoor Block Group Not GoodExcellent Tract PoorGood

GEOG 111/211A Transportation Planning Model Formulation and Surveys Privacy –May limit data collection efforts –Private information must remain secure Response Rate –Good survey should have at least 85% response rate Representative Sample Size –Pop. representation most important Model Stability and Transferability –Over time, behavior may change –Behavior is not necessarily the same from place to place

GEOG 111/211A Transportation Planning Trip Generation Example Similar to the lab exercise From the Puget Sound Region in 1989 Subsistence (work + school trips) These are one way trips (origins) instead of productions

GEOG 111/211A Transportation Planning Sample Descriptives Class: What do you observe?

GEOG 111/211A Transportation Planning Trip Generation Linear Regression Model for Subsistence Trips Class: Interpret the model

GEOG 111/211A Transportation Planning Goodness of fit

GEOG 111/211A Transportation Planning Let’s Improve the Model If (age < 20) Teen = 1. If (age >= 20 and age < 35) Young=1. If (age >= 35 and age < 65) Midage=1. If (age >= 65 and age < 75) Senior=1. If (age >=75) VSenior=1.

GEOG 111/211A Transportation Planning Descriptives of the New Vars

GEOG 111/211A Transportation Planning Linear Regression

GEOG 111/211A Transportation Planning Leisure Trip Generation The same model as for subsistence did not work!!!!!

GEOG 111/211A Transportation Planning New model for leisure

GEOG 111/211A Transportation Planning Goodness of fit

GEOG 111/211A Transportation Planning Compare frequencies Class: Which one is easier to estimate?

GEOG 111/211A Transportation Planning Traditional Trip Generation Input: social and economic characteristics Output: productions/attractions, origins/destinations by zone Key concepts: trip generation by purpose maybe more accurate but some purposes easier to predict (trips to work) Other: Goods movement productions/attractions are handled in a similar way (Freight Forecasting Manual exists)

GEOG 111/211A Transportation Planning Post-MTC Lawsuit Models Level of service = “quality” of transportation system measured in travel time from an origin to a destination Trip generation also function of level of service New models for induced demand = new demand for travel after improvements in level of service Activity-based models to reflect “scheduling” of persons, coordination of activities Multilevel models to reflect within group coordination

GEOG 111/211A Transportation Planning In the Lab - Check TAZ population and productions Businesses and attractions What do you expect the relationship to be? Does the relationship make sense?

GEOG 111/211A Transportation Planning Summary Collect data using surveys Derive a model using statistics Use the model to predict number of trips generated in each zone Apply this at each centroid representing a zone Have all this ready for the next step – trip distribution If you cannot run a survey – use equations from ITE trip generation manual or other studies – check for similarities/verify results!