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Data Integration for Small Geography Origin-Destination Trip Tables


In an effort to increase data reliability, utilizing data from multiple sources can increase the accuracy or at least lessen the effects of missing pairs. The Census Transportation Planning Products (CTPP) and the Longitudinal Employer-Household Dynamics (LEHD) both produce home to work origin-destination data at small geography and both data sources have many strengths. LEHD has the advantage of the workplace information coming from administrative records assuming the workers work at a centralized location. CTPP, on the other hand, picks up the actual work location from the worker regardless of the employer location. In addition to combating the difficulties in determining the workplace geography for most workers, the CTPP and LEHD can be used to validate the overall trends seen in flows from home geography to work geography.

After Census 2000, the CTPP began to utilize data drawn from the American Community Survey which has a smaller sample size, nationally, than the long-form of the Census. As a result there is less data available for worker flow generation. Furthermore, concern about respondent confidentiality has made it necessary for the Census Bureau to engage in stricter protection of the data which is particularly detrimental to worker flow data. In addition to data swapping and top-coding which are standard approaches to protecting the identity of respondents, any geographical flow pair must have at least three observations for the flow to be shown. With a diminished sample size, this greatly reduces the effectiveness of the dataset for small geography.

On the other hand, LEHD has long had a “headquarters” problem. Many workers work at a different location than the official address of their employer. Some employer types are not included such as active duty military and until very recently all levels of civilian government. Also CTPP only records a person's primary job, so any comparative analysis with the data requires the user to remove other jobs held for any worker with more than one.


The purpose of this research is to explore ways to combine the CTPP and LEHD flows at small geography. This is not an additive exercise since both datasets overlap one another to some degree. The challenge is to determine to what degree the two datasets overlap and what degree they are complimentary. This is particularly valuable as inputs into local and regional travel demand models for long range transportation plans, resulting air quality analysis, and environmental impact studies. This is also relevant for transportation planners who utilize model outputs as well as planners conducting analysis using flow input data. This is the first step in a greater effort to combine data from different sources to get at the “truth” in terms of work trip flows that drive so much of the transportation infrastructure.

Sponsoring Committee:AED20, Urban Transportation Data and Information Systems
Research Priority:High
RNS Developer:Mara Kaminowitz and Clara Reschovsky
Source Info:ABJ30(1) and CTPP program
Date Posted:12/28/2016
Date Modified:04/20/2018
Index Terms:Data collection, Data quality, Origin and destination, Trip tables, Workplaces, Households, Travel surveys,
Cosponsoring Committees: 
Data and Information Technology
Planning and Forecasting
Transportation (General)

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