The National Academies

NCHRP 08-123 [Active]

Census Transportation Data Field Guide for Transportation Applications

  Project Data
Funds: $500,000
Staff Responsibility: Christopher McKenney
Research Agency: Cambridge Systematics
Principal Investigator: Krishnan Viswanathan
Effective Date: 5/15/2019
Completion Date: 3/31/2022


The Census Transportation Planning Products (CTPP) data sets and the American Community Survey (ACS) are critical data elements that support analysis of transportation planning, policies, programs, and project selection.  As a result of changes in the data products over the last 10 years, ongoing staff turnover, and emerging technologies, many transportation agencies find themselves without the necessary expertise to use this data effectively to support transportation analyses.  In addition, there is no centralized resource to learn how to use the data for real world applications, resulting in wasted time and resources and questionable analyses.

When the Census Bureau introduced the ACS as the replacement to the Long Form, it brought with it a change in how the data were collected and packaged for public release.  This change in turn brought a whole new set of data issues for the transportation analyst.  Large margins of error, privacy protection rules and procedures, imputation, rounding, data suppression, changes to the survey instrument and variables, and period estimates all have stretched the learning curve for the user.   Staff from state departments of transportation (DOTs), metropolitan planning organizations (MPOs), and transit operators all have struggled with the use and application of the ACS and data products derived from it, such as the CTPP and Public Use Microdata Sample/Public Use Microdata Area (PUMS/PUMA).  A detailed guide addressing these various problems and issues would facilitate improved use of available data and application of related analytical strategies and tools.


The objective of this research is to develop a field guide for the transportation community on how to best use Census data, including the ACS, CTPP, LODES Employment-Household Dynamics (LEHD), and PUMS/PUMA, to address transportation issues. 

The field guide is expected to play a critical role in enabling users at all levels to learn about and apply census data and its derivatives—efficiently, empirically, and economically.  Research teams are encouraged to be creative in their suggestions for alternative media targeted to specific audiences as a final product to increase awareness of the field guide.


Proposers are asked to present a detailed research plan for accomplishing the project objective.  Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time, including an indication of how proposed research will make use of and build on available resources.  Proposals must demonstrate in sufficient detail an understanding of the issues and a sound approach to meeting the research objectives, including prioritizing critical issues.  It should also include a review of other related studies in general and NCHRP research studies in particular. 

At a minimum, the product of this research should 

1.    Clearly define available data and provide analytical methods for what the data can or cannot be used for, explaining technical issues regarding margins of error, geography, data suppression, data imputation, rounding, perturbation, data currency/period estimates, and other relevant factors;

2.    Describe approaches for using data to address transportation issues, including travel demand modeling, equity analysis, resiliency planning, dynamic travel patterns, disruptive technologies, alternative commute opportunities, new data sources (location-based services), and new data techniques (data fusion, such as with the National Household Travel Survey data, transaction data, probe data, etc.);

3.    Illustrate data usability with case studies varied in size as well as complexity, including applications that cross industries (public and private) and agencies, from local to national, and from single to multimodal where possible;

4.    Explore options for data access: e.g., Application Programming Interface (API), File Transfer Protocol (FTP), web access, data services, and issues with data governance;

5.    Distill critical findings into a product separate from the field guide suitable for broad presentation, communication, and dissemination.

6.    Serve as a field guide and training reference on the uses and application of the ACS, CTPP, LEHD, and PUMS/PUMA data sets;

7.    Provide practitioners with a thorough understanding of the datasets, including a comparative analysis characterizing strengths and weaknesses for given applications, reflecting an historical perspective;

8.    Identify and include metadata—describing content, methods and timeliness of the data, and details of the table structures and variable definitions;

9.    Instruct users on when and how to use the data with real world and visual examples, from different types of transportation agencies including local agencies, state DOTs, and MPOs, addressing multi-modal applications.

10.  Explore potential substitutability of “Big Data” for those census data uses where new sources of data can expand applications, addressing privacy issues, security, reliability, and other issues.

The research plan should be presented as a two-phase effort and should describe specific tasks for each phase, including interim and final deliverables. 

Phase I

The research team will develop a framework to illustrate the organization and application of various datasets, both existing and potential.  In addition, the team should include a description and evaluation of shortcomings as well as suggested potential approaches for improving, eliminating, and/or expanding applications, an annotated outline of the proposed field guide, and a detailed scope of work for preparation and testing the field guide that will occur in Phase II. 

The product of Phase I will include an interim report that presents a detailed framework for developing the field guide: a review of known and anticipated issues, a summary of current applications using the datasets, and an annotated outline of the proposed guide.  As indicated, the interim report will also include the detailed scope of work for preparation and testing of the field guide in Phase II.  Phase I should account for no more than 30% of the overall effort.  The NCHRP panel will meet with the research team at the end of Phase I to review the interim report.  NCHRP will approve the Phase I interim report prior to moving on to Phase II. 

Phase II

Work in Phase II will encompass the tasks necessary to produce the field guide, including a process to validate the usefulness and applicability based on case studies, through workshops or other options.  Final products of phase II should also include any training materials, tools, or other innovative resources to enhance usability; a discussion of strategic approaches to and risks associated with data mining; and recommendations for effective dissemination of the guide.  It should also include presentation materials to enhance dissemination and awareness of the field guide. 

The research plan should build in appropriate checkpoints with the NCHRP project panel including, at a minimum, (1) a kick-off teleconference meeting to be held within 1 month of the contract’s execution date; (2) the face-to-face interim deliverable review meeting to be held at the end of Phase I; and (3) at least two additional web-enabled teleconferences tied to NCHRP review and approval of any other interim deliverables as deemed appropriate.

Note: The cost of teleconferences, in-person meeting venue, and NCHRP panel member travel will be paid by NCHRP.

Final Deliverables

Final deliverables will include at a minimum: (1) the field guide; (2) a final report that documents the entire research effort; (3) an executive summary as a stand-alone document that outlines the research findings and recommendations; (4) a presentation for state DOT staff and senior management that simply and concisely explains why the field guide and supporting materials are helpful and how they will be used; and (5) an executive-level brochure/infographic summarizing salient findings of the field guide suitable for an executive/senior management audience.  Any tools developed as part of the research program will use open source or commonly used software. 

Final deliverables will also include a stand-alone technical memorandum entitled, “Implementation of Research Findings and Products.” 

STATUS: Phase I of the study is now underway..

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