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Uses of Census Data in Transportation

Data Evaluation and Enhancement

A Guidebook for Using American Community Survey Data for Transportation Planning

Authors: McGuckin, Nancy; Ruiter, Earl Cambridge Systematics, Incorporated-100 Cambridge Park Drive, Suite 400 Cambridge, MA 02140 ; NuStats, LLC-3006 Bee Caves Road, Suite A-300 Austin, TX 78746

Publication Date: 2007

Abstract:

Census data have long played a central role in transportation planning and analyses. In particular, the planning community has made extensive use of the Census Long Form. Beginning with this decade, the Census Bureau's American Community Survey (ACS) will replace the Census Long Form. This practitioner's guidebook focuses on incorporating ACS data into the transportation planning processes at national, state, metropolitan, and local levels. The guidebook evaluates ACS data and products and demonstrates their uses within a wide range of transportation planning applications. Transportation planners, travel demand forecasters, and others that conduct population and demographic analyses will find this report of significant use. As these transportation professionals struggle to use the limited local data and changing national data as the basis for transportation plans, the report will provide methods and tools to improve the connection between planning and programming.

Subject Areas and Index Terms

Administration and Management; Data and Information Technology; Planning and Forecasting; Transportation (General); I72: Traffic and Transport Planning

Census; Demographics; Forecasting; Handbooks; Programming (Planning); Surveys; Transportation planning; Travel demand; American Community Survey

Availability: Transportation Research Board Business Office Order URL: http://trb.org/news/blurb_detail.asp?id=8523

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Order URL: http://worldcat.org/isbn/9780309099110

Data Evaluation and Enhancement

Assessing the Accuracy of Agency Population Projections for Texas's Metropolitan Statistical Areas

Authors: Weston, Lisa Marie; Bomba, Michael S Transportation Research Board-500 Fifth Street, NW Washington, DC 20001

Transportation Research Board 87th Annual Meeting

Publication Date: 2008

Abstract:

Long-range, regional demographic projections are a critical component of local government planning for future infrastructure and services. However, because local governments frequently update studies, the accuracy of population projections is often not rigorously challenged. Inaccurate long-range demographic projections can have potentially serious consequences when they are incorporated into the traffic and revenue studies required to sell the commercial bonds needed for the construction of toll roads. Under these circumstances, tolling entities can incur significant expense or even jeopardize their credit worthiness, if grossly inaccurate demographic forecasts overestimate future toll road revenue. Alternatively, exceedingly low demographic projections may make a proposed toll road unable to secure financing or may lead toll agencies to pay higher bond rates than necessary. This paper reports the preliminary results of an ongoing study to assess the accuracy of agency-prepared demographic projections for the largest metropolitan statistical areas (MSAs) in Texas. Twenty different agency population projections prepared between 1958 and 1989 were collected and assessed against U.S. Census data for this study. The researchers found these agency population projections were frequently inaccurate and sometimes with a high margin of error. Not surprisingly, the margins of error tended to be greater in fast growing regions and in regions with volatile local economies. In some instances, population projections for early forecasts periods also had relatively high margins of error, thus reinforcing the assumptions of private sector investors who believe that significant risks exist at the early stages of bond repayment for tolled facilities.

Subject Areas and Index Terms

Data and Information Technology; Finance; Highways; Planning and Forecasting; Terminals and Facilities; I10: Economics and Administration; I72: Traffic and Transport Planning

Bonds; Finance; Revenues; Statistical analysis; Strategic planning; Toll facilities; Toll roads; Texas

Availability: Transportation Research Board Business Office

Data Evaluation and Enhancement

Design Considerations to Mitigate Non-Response in Regional Household Travel Surveys

Authors: Bricka, Stacey Transportation Research Board-500 Fifth Street, NW Washington, DC 20001

10th National Conference on Transportation Planning for Small and Medium-Sized Communities

Publication Date: 2006

Abstract:

Household travel surveys provide demographic and travel behavior details that inform the transportation planning process in general and regional travel demand modeling in particular. They are typically conducted about once every 10 years, based largely on the availability of funding. These surveys document details such as mode of travel, time of day that travel is taking place, and the reasons for travel. The data are used to generate trip rates, build origin-destination tables, and update other assumptions used in the development of a regional travel demand model. They also help to inform policy decisions and prioritize infrastructure investments. Since the late 1970s, most household travel surveys in the US have been conducted using a combination of telephone and mail. Households are randomly sampled, contacted about participating in the study, and, if amenable, are provided with travel logs or diaries for household members to use to document their travel for a specific time period, most often 24-hours. They are either recontacted by telephone to retrieve their travel information or asked to mail these logs back to a central location for processing. The final data sets provide detailed travel behavior information for the region. Despite the importance of this data in planning for the region's mobility needs and addressing critical transportation-related questions, not all sampled households participate in household travel surveys. Some refuse to participate because of the intrusiveness or time associated with the task of recording all travel for the 24-hour period or because they feel disenfranchised. These refusals are sometimes direct ("don't call me again!") and sometimes indirect (they don't answer their phones). A second group of respondents might be interested in responding but are not home when the telephone interviewers attempt to contact them. A third respondent type includes those without telephones or with cellular-only service, who are not included in a random telephone sample so they are not called at all. All these households travel in the region and contribute to the congestion and other problems to be addressed in the planning process. "Non-response" is a term typically used to refer to the phenomenon that not all sampled households opt to participate in a survey. It is typically measured through comparing the demographics of participating households to the study area population (typically using census data). While slight variations between the population and sample are to be expected, certain sub-population groups tend to be consistently under-represented in the sample. Prior research has shown these groups to include one-person/one-worker households, larger households, lower income households, and minority households. The purpose of this paper is to summarize the population subgroups commonly under-represented in travel surveys, focusing primarily on studies in small and medium-sized communities. A synthesis of the non-response findings from those studies is presented and categorized. For each group, specific design and procedural recommendations effective in other studies are presented. This is followed by a case study of how a transportation planner can use census data to pre-identify potential non-responders in a given region, and how to select methods or processes to mitigate non-response in that region's travel survey. The important consideration is that these improvements can be built into the design at the start of the study, thus avoiding costly survey corrections while enriching the representativeness of the final data set in an efficient manner. The result is a step-by-step plan for identifying potential non-respondents up front and ensuring that the travel survey design incorporates measures to attract and maintain these groups in the final data set.

Subject Areas and Index Terms

Data and Information Technology; Highways; Planning and Forecasting; Society; I72: Traffic and Transport Planning; Census; Households; Medium sized cities; Small cities; Transportation planning; Travel surveys; Nonresponse (Surveys)

Availability: Transportation Research Board Business Office

Data Evaluation and Enhancement

Development of Zonal Employment Data for Delaware Valley Region Based on Census 2000

Authors: Zakaria, Thabet Transportation Research Board-500 Fifth Street, NW Washington, DC 20001

Evaluation of Census Transportation Planning Package 2000 for the Delaware Valley Region

Publication Date: 2006

Abstract:

Accurate zonal employment data is required for travel analysis, travel forecasting, transportation planning, and economic development projects. This paper describes the methodology used by DVRPC to develop 2000 zonal employment data or total jobs estimates for the Delaware Valley region based on the census employed persons at work, which are included in the Census Transportation Planning Package 2000 and the journey-to-work traffic flows. A three-step method was used to develop county, municipal, and zonal employment estimates for the region, which includes 9 counties, 355 municipalities, and 1,912 Traffic Analysis Zones. The Census Bureau is the only agency that provides employed persons data at the zonal level. Employment estimates from the Bureau of Economic Analysis, Bureau of Labor Statistics, Pennsylvania and New Jersey Departments of Labor (ES-202), and local data such as the Pennsylvania occupational privilege tax records were used to compare the employment estimates developed by DVRPC. The DVRPC county, municipal, and zonal employment estimates are based on quality data from Census 2000 and are consistent with other federal, state, and county estimates. The 2000 count and characteristics of workers produced by the Census Bureau are reasonable and consistent with the census definition of employed and unemployed persons. Although it does not include the number of total jobs and comparable Standard Industrial Classification sectors, CTPP 2000 data can be adjusted easily and utilized in transportation and regional planning studies such as travel simulation, trend analyses, job access, reverse commuting, and the preparation of transportation plans and programs.

Subject Areas and Index Terms

Data and Information Technology; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure

Census; Employment; Estimates; Forecasting; Statistics; Pennsylvania

Availability: Transportation Research Board Business Office Order URL: http://trb.org/news/blurb_detail.asp?id=1121

Data Evaluation and Enhancement

Evaluation of Census Transportation Planning Package 2000 for the Delaware Valley Region

Authors: Zakaria, Thabet Transportation Research Board-500 Fifth Street, NW Washington, DC 20001

Transportation Research Board 85th Annual Meeting

Publication Date: 2006

Abstract:

In this paper, the Census Transportation Planning Package 2000 (CTPP 2000) for the Delaware Valley region is described, analyzed, and evaluated with special emphasis on the journey-to-work trip data, means of transportation, travel time, employed persons at work, employment, households, vehicle availability, and other data required for transportation planning. The evaluation of Parts 1 and 2 of CTPP 2000 indicated several errors in the data, which were corrected by DVRPC before the data was used in various transportation planning projects. However, data disclosure rules, applied to some tables in Part 3, made the zone-to-zone worker flows by means of transportation totally useless. Except for such tables, CTPP 2000 data is generally accurate and useful for transportation and economic development studies. But, the data should be reviewed and adjusted, if necessary, before they are utilized in transportation planning projects. Based on this evaluation, a set of eight recommendations regarding sample size, nonresponse and imputation, public relations and marketing, place of work coding, processing, data rounding, swapping, and disclosure threshold is proposed. Except for development of a 20 percent sub-sample to improve the accuracy of the responses to the questionnaire, change to rounding rules, and elimination of disclosure threshold, these recommendations are completely consistent with those used by the Census Bureau in Census 2000. Almost all of the CTPP 2000 errors can be avoided if these recommendations are implemented in the future. This is especially important since the overwhelming majority of users cannot review the CTPP data, identify errors, and make appropriate corrections. DVRPC expects the next CTPP to contain accurate data that can be used without any major correction or adjustment. The CTPP is the most efficient and convenient way for obtaining census data to support a wide range of transportation planning studies.

Subject Areas and Index Terms

Data and Information Technology; Highways; Planning and Forecasting; I21: Planning of Transport Infrastructure

Accuracy; Census; Data quality; Statistics; Transportation planning; Census Transportation Planning Package

Availability: Transportation Research Board Business Office Order URL: http://trb.org/news/blurb_detail.asp?id=1121

Data Evaluation and Enhancement

Household Travel Surveys with GPS: An Experiment

Authors: Bricka, Stacey; Zmud, Johanna P; Wolf, Jean L; Freedman, Joel

Transportation Research Record: Journal of the Transportation Research Board

Publication Date: 2009

Abstract:

This paper documents the results of a pilot test done for the Oregon Household Travel Survey. The pilot was designed to enable the Oregon Department of Transportation to determine the role of a Global Positioning System (GPS) in the upcoming survey effort. Specifically, a three-pronged approach was employed. Households were randomly selected for inclusion in the study and then assigned to one of three groups: (a) the traditional survey approach, (b) the traditional approach with GPS, and (c) GPS only. A total of 299 households from the city of Portland, Oregon, were recruited into the pilot, with 235 completing all required activities. A comprehensive evaluation of the similarities and differences in results across the three groups showed differences in respondent burden, completeness of travel details obtained, and costs. Results from this experiment also showed differences in nonresponse bias. The traditional survey had an expected nonresponse for the large households, low-income households, and young adults. Minority participation was on par with census figures. The GPS groups showed higher participation rates for young adults and nonminorities. These data confirmed the general thought that GPS was an effective tool for mitigating nonresponse among young adults. However, the minority nonresponse bias increased significantly with technology, suggesting that other methods would be more appropriate. With regard to completeness of data, geocoding rates are higher for the GPS groups, and there are significant differences in trip departure times, which could affect peak hour and time-of-day modeling. As expected, the costs were higher for the GPS groups, but the expectation is that these costs will fall as processes are standardized across studies and new technologies are introduced.

Subject Areas and Index Terms

Data and Information Technology; Highways; Planning and Forecasting; I72: Traffic and Transport Planning

Bias (Statistics); Costs; Data quality; Demographics; Global Positioning System; Households; Low income groups; Minorities; Pilot studies; Socioeconomic factors; Travel surveys; Young adults; Portland (Oregon); Nonresponse (Surveys)

Availability: Transportation Research Board Business Office Order URL: http://trb.org/Main/Blurbs/Information_Systems_Geographic_Information_Systems_162392.aspx

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Order URL: http://worldcat.org/isbn/9780309126205

Data Evaluation and Enhancement

Longitudinal Employer-Household Dynamics as a Source for Journey to Work Flow Data

Authors: Viswanathan, Krishnan; McWethy, Laura; Tierney, Kevin F Transportation Research Board-500 Fifth Street, NW Washington, DC 20001

Transportation Research Board 89th Annual Meeting

Publication Date: 2010

Abstract:

The move to the American Community Survey (ACS) will significantly affect how transportation planners access, use, and interpret Census data. Among the various issues that affect transportation planners, one of the main concerns is that the ACS samples 1 in 40 households as compared to the Decennial Census Long Form that sampled 1 in 6 households and the corresponding limitations on data available for public release. Therefore, synthetic data sources such as the Longitudinal Employer Household Dynamics (LEHD) need to be considered as a source of journey to work flow information. Data comparisons at the state, county and block level do not show discernible trends in terms of whether the ACS or the LEHD estimates employment and workplace location better. When considering trip length distribution for home to work, the LEHD consistently has longer trips than the ACS at the county level. However, when considering MPO areas with multiple counties, the trip length distributions are much closer with the LEHD trip length just slightly longer than the ACS in most instances. While the LEHD can be a potential source of data for calculating journey to work flow and enhancing the ACS, further work using microdata at the Census Bureau is needed to conclusively determine whether this potential can be realized.

Subject Areas and Index Terms

Data and Information Technology; Highways; Transportation (General); I72: Traffic and Transport Planning

Census; Data quality; Longitudinal studies; Metropolitan areas; States; Statistical sampling; Transportation planning; Travel time; Trip length; Work trips; American Community Survey

Availability: Transportation Research Board Business Office

Data Evaluation and Enhancement

Model-Based Synthesis of Household Travel Survey Data in Small and Midsize Metropolitan Areas

Authors: Long, Liang; Lin, Jie; Pu, Wenjing

Transportation Research Record: Journal of the Transportation Research Board

Publication Date: 2009

Abstract:

Household travel data synthesis-simulation has become a promising alternative or supplement to survey data from both small urban areas and large metropolitan regions in which data are expensive to collect or the data required to support the planning process have become outdated. This paper proposes and applies model-based approaches [i.e., small area estimation (SAE) methods] to synthesize household travel characteristics. The proposed methods address the sampling-bias concerns in the existing methods. Specifically, three SAE methods "the generalized regression estimators method, the empirical best linear unbiased predictor (EBLUP) method, and the synthetic method (an EBLUP without random area effects)" are applied to synthesize household travel characteristics at both census tract and individual levels. The SAE framework of synthesizing household travel characteristics is demonstrated with the National Household Travel Survey data and the Census Transportation Planning Package data in the Des Moines metropolitan area in central Iowa. Results indicate that SAE methods are promising approaches to synthesize unbiased aggregate and disaggregate household travel characteristics by incorporating population auxiliary information and local, small-household travel survey data. The proposed data synthesis methods and analysis findings will provide a useful tool for practitioners, planners, and policy makers in transportation analyses. The paper also points out that by linking population synthesis with the travel data simulation framework described here, this method could be of broad application in transportation planning.

Subject Areas and Index Terms

Data and Information Technology; Highways; Planning and Forecasting; I72: Traffic and Transport Planning

Data quality; Households; Mathematical models; Metropolitan areas; Representative samples (Statistics); Transportation planning; Travel demand; Travel surveys; Des Moines (Iowa); Data synthesis; Synthesized travel characteristics

Availability: Transportation Research Board Business Office Order URL: http://trb.org/Main/Blurbs/Information_Systems_Geographic_Information_Systems_162392.aspx

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Order URL: http://worldcat.org/isbn/9780309126205

Data Evaluation and Enhancement

Retrospective Analysis of Population Projections - 25 Years Later

Authors: Baltz, David K Transportation Research Board-500 Fifth Street, NW Washington, DC 20001

11th National Conference on Transportation Planning for Small and Medium-Sized Communities

Publication Date: 2008

Abstract:

One aspect of population projections used for traffic modeling in small and medium sized cities and counties is that agencies seldom if ever go back to evaluate how accurate their long range projections have been. Typically once a new or revised set of projections are made, the old projections are quickly forgotten long before the horizon year is ever reached. This paper and presentation will provide a post horizon-year retrospective evaluation and analysis of a set of 20-year population projections I prepared in the early 1980's for the Stanislaus Area Association of Governments when I was employed by Stanislaus County, California. These projections were important because they set new countywide population control totals, which were later disaggregated to the cities and to traffic analysis zones for land use and transportation planning. The population projections were prepared following the 1980 Decennial Census using three relatively independent methodologies, with several alternatives run for each. These methods can be described as 1) a trend extrapolation method that used past population levels and a simple regression model, 2) an employment based method, which combined employment projections with projections of future labor force participation rates to determine future population, and 3) a cohort component model, which utilized interstate and inter-county migration trends to project the net migration component. In using three different methodologies it was hoped that some consistent future population levels would emerge. This approach was successful in this regard. On the surface, it appears that the 20-year projections prepared in the early 1980's were actually quite accurate. But this analysis will dig deeper into the data to try to determine if this accuracy was attained by the quality of the methods used or merely by random chance. This paper and presentation will look at the various factors that went into the three methodologies and compare assumptions with what actually transpired over the 20-year period. Some of these factors included employment growth, changes in labor force participation rates, net migration to Stanislaus County, and natural increase (fertility and survival rates). The impact of each of these factors on the accuracy of the projections will be evaluated. Projecting is a difficult business. Very seldom are we able to give true estimates or probabilities of the expected accuracy of our projections. This analysis is a once in a career opportunity to try to get a handle on this question of population projection accuracy. Hopefully this paper and presentation can add to a limited literature on the subject.

Subject Areas and Index Terms

Highways; Planning and Forecasting; I72: Traffic and Transport Planning

Labor force; Long range planning; Population forecasting; Population growth; Traffic models; Transportation planning; Stanislaus County (California); Retrospective analysis

Availability: Transportation Research Board

Data Evaluation and Enhancement

The ACS Statistical Analyzer

Authors: Chu, Xuehao University of South Florida, Tampa-National Center for Transit Research, 4202 East Fowler Avenue Tampa, FL 33620-5375 ; Florida Department of Transportation-605 Suwannee Street Tallahassee, FL 32399-0450 ; Department of Transportation-Office of Re

Monograph

Publication Date: March 2010

Abstract:

This document provides guidance for using the ACS Statistical Analyzer. It is an Excel-based template for users of estimates from the American Community Survey (ACS) to assess the precision of individual estimates and to compare pairs of estimates for their statistical differences. The ACS Statistical Analyzer covers the following four functions and fifteen sub-functions (not listed): (1) To derive other precision measures for published ACS estimates at American FactFinder or from the Census Transportation Planning Products (CTPP), which already have a margin of error (MOE); (2) To derive the precision measures for estimates that do not already have an MOE; (3) To derive the precision measures of new estimates obtained from two or more original estimates that already have an MOE; and (4) To compare pairs of two estimates that already have an MOE. Measures of precision for an estimate include its MOE, relative reliability, and confidence interval. The implementation of the ACS Statistical Analyzer is expected to reduce the agency cost of, and to lessen the technical barriers to, dealing with the precision of ACS estimates when agencies use these estimates. These direct benefits in turn can lead to wider and more effective usage of ACS data.

Subject Areas and Index Terms

Data and Information Technology; Planning and Forecasting; Public Transportation; I72: Traffic and Transport Planning

Estimates; Precision; Public transit; Statistical analysis; ACS Statistical Analyzer; American Community Survey

Availability: National Technical Information Service

Data Evaluation and Enhancement

Transportation Planning Capacity Building Peer Exchange Using ACS Data in Transportation Planning Applications

Authors: American Association of State Highway and Transportation Officials-444 North Capitol Street, NW Washington, DC 20001

Publication Date: 2007

Abstract:

This report summarizes the presentations and discussions at a Peer Exchange held through the FHWA/FTA Transportation Planning Capacity Building (TPCB) Program. The peer exchange was organized by the American Association of State Highway and Transportation Officials (AASHTO) Standing Committee on Planning (SCOP) Census Data Workgroup. Attendees were from AASHTO, state departments of transportation, metropolitan planning organizations and councils of government, universities, Census Bureau, the United States Department of Transportation, and the private sector. Following the keynote addresses, issue-specific sessions were held in which multiple presenters gave short presentations and all participants joined in discussion. Transportation planners and analysts are making or contemplating a transition from using data from the decennial Census "long form" to the new American Community Survey (ACS).

Subject Areas and Index Terms

Data and Information Technology; Highways; Planning and Forecasting; I72: Traffic and Transport Planning

Census; Transportation planning; American Community Survey; Application data; Data sources; Peer exchange; Transportation data

Descriptive Analysis

American Community Survey 2005: San Francisco Bay Area Data Summary

Authors: Metropolitan Transportation Commission-101 Eighth Street Oakland, CA 94607-4700

Monograph

Publication Date: July 2007

Abstract:

This report contains selected tabular summaries of data for the San Francisco Bay Area from the American Community Survey (ACS) 2005. Focus of the report is on the ACS 2005 data and on the comparisons of the ACS 2005 data with that of data from the Census 2000. Tables in the data summary are tabulated according to the following themes: 1) household and population characteristics; 2) race and ethnic characteristics; 3) social/economic characteristics; 4) labor force characteristics; and, 5) commute/journey to work characteristics.

Subject Areas and Index Terms

Data and Information Technology; Economics; Highways; Society; I10: Economics and Administration

Census; Commuting; Demographics; Ethnic groups; Households; Income; Labor force; Occupations; Population; Race; Statistics; Tables (Data); Work trips

Availability: Available from UC Berkeley Transportation Library through interlibrary loan or document delivery Order URL: http://library.its.berkeley.edu; Metropolitan Transportation Commission.

Updated: 06/06/2011
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