Task Order 5110
Policy and Behavioral Research
A GIS-based Tool for Forecasting the Travel Demands
of Demographic Groups within California
&mdash An Optimal Resource Allocation Tool
Konstadinos G. Goulias
Geography Department
University of California, Santa Barbara
Overview
Assessments of transportation investment from a "social efficiency" viewpoint are absent from transportation practice. This is mainly due to the lack of tools capable to assess the role of transportation investments on the efficient allocation of time by the residents of each locality. In this project we will develop a tool that identifies specific locations in the state where resource allocation has succeeded in maximizing benefits to the public. In addition, the tool and the map derived from this tool will show which locations in California fail to be optimal and require their residents to travel excessively to pursue the same amount of activities when compared to other optimal locations around the state where traveling enables better time allocation. Most important the tool will also be able to show which demographic segments suffer the most from suboptimal time allocation and what type of investment is needed to alleviate this suffering. In addition, this new tool will show the distribution of benefits of the transportation system and will identify differences in benefits across demographic segments.
The tool will be designed as a Geographic Information System tool that computes the quality of service offered by the transportation system at different locations using data about individuals and their households as well existing databases of infrastructure investment. Using statistical techniques, levels of service offered by the transportation system will be correlated to the social and demographic characteristics of residents throughout California. The GIS maps will provide a visualization of this relationship in space and across demographic segments to aid Caltrans and other cognizant agencies in planning efficient and optimal allocation of resources.
Tasks
The project is comprised of two distinct phases. The objective of the first phase is to produce a statewide tool for efficiency measurement that is primarily based on available data and off-the-shelf software tools. The objective of the second phase is to explore a more detailed, more precise, and more accurate methodology that will be tested in Santa Barbara. Lessons learned from the Santa Barbara case study will pave the way for statewide deployment. The overall methodology we will use in this project is described in the following steps.
Step 1 &mdash Time Allocation Equations:
Develop activity/travel demand equations that can represent the entire state using recent survey data. The main data source for developing the activity-based travel demand equations will be the 2001 Caltrans California Statewide Household Travel Survey
http://www.dot.ca.gov/hq/tsip/TSIPPDF/2000_Household_Survey.pdf.
Step 2 &mdash Develop an inventory of facilities and quality of service indicators
Members of this team developed in other projects accessibility indicators using existing data on highways and public transportation, travel time inventories, and largely available census information.
Step 3 &mdash Develop Statewide Predictions using PUMS & Microsimulation
Public Use Microdata Samples (PUMS) is a 5% sample of the US Census population http://www.census.gov/acs/www/Products/PUMS/ at it is available at the individual person and household levels. It contains almost all the social and demographic details collected by the Census 2000. This database will be used to predict costs (travel) and benefits (time to activities) for the entire state by complete enumeration (i.e., use the person-by-person equations from Step 1 to predict dependent variables as a function of the observed social and
demographic characteristics in PUMS).
Step 4 &mdash Production function and optimal resource allocation
Data Envelopment Analysis (DEA), will be used to compute a scalar measure of efficiency and determines efficient levels of inputs and outputs for the California regions under evaluation.
Step 5 &mdash Build Maps
Using GIS data from the 2000 Census Transportation Planning Package (CTPP) http://www.fhwa.dot.gov/ctpp/ and as explained above we will then predict (using complete enumeration) and expand to the whole population action spaces, accessibility measures, and travel behavior patterns.
In this project a unique collaboration between the University of California at Irvine with the University of California at Santa Barbara is envisioned. PATH divided the project into two independent tracks for each of the two campuses that will be progressing in parallel to accomplish the project mission. UC Irvine will emphasize model estimation and UC Santa Barbara will emphasize development of the optimal resource allocation assessment and map creation as well as overall project oversight. Project completion is expected to be in August 2006.
|