Transit Data Shed Light on Ridership Trends, Service Impacts

Transit agencies across the country conduct detailed passenger studies and surveys to better understand transit passenger trends. The data from many of these studies are now housed in the transit passenger data section of the Transportation Secure Data Center (TSDC) at the National Renewable Energy Laboratory (NREL).

“The TSDC hosts data from some of the largest transit systems in the country,” said NREL Transportation Researcher Joe Fish, who manages the TSDC. “These data provide transit agencies, transportation planners, and mobility researchers with real-world insights on public transit ridership and service trends.”

Growing Archive of Data From Transit Passenger Studies and Surveys
With funding from the Federal Transit Administration, the TSDC’s transit section was created in collaboration with Kansas State University to provide a centralized archive for passenger transit data from across the nation. Since then, the data archive has continued to grow.

“Researchers and planners can use the data for myriad types of analysis—to better understand how a transit system is being used, to see how well it meets the needs of disadvantaged communities or people with disabilities who may rely on public transit, or to gain insight into the long-term trends resulting from the COVID pandemic, for example,” said NREL Researcher Venu Garikapati, who leads the Transportation Modeling and Metrics team. “Public transit also has an important role to play in decarbonizing the transportation system—understanding use patterns is critical to improving transit service and ultimately increasing its use.”

The TSDC’s transit data downloads include accompanying documentation, such as summary reports, survey instruments, and targeted metadata to help users quickly sift through the available data and understand the fields it contains. Metadata spans the name of the survey and transit agency, the transit agency’s unique five-digit National Transit Database code, the year the survey was conducted, the travel mode (i.e., bus, light-rail, vanpool, etc.), the types of data available, the data-collection method, and the recruitment method and related incentives.

“As data-collection methods change over time, shifting from paper, phone, or GPS-based collection to more automated electronic methods, the types of data we host will continue to evolve,” Fish added.

About the Transportation Secure Data Center
The new transit-oriented section builds on the TSDC’s long-standing household travel data section, which NREL launched more than a decade ago in partnership with the U.S. Departments of Energy and Transportation and now houses data from more than 100 travel studies and surveys conducted across the nation.

The TSDC provides free access to data from surveys and studies while preserving the privacy of individual participants. Cleansed data, with personally identifiable information removed, are readily available for download via the TSDC website after a simple, one-time registration process. Meanwhile, more detailed spatial data are accessible to approved users via a restricted and secure virtual connection.

Before adding new data packages to the TSDC, NREL screens the initial data for quality control, translates each data set into a consistent format, and interprets the data for spatial analysis. For household travel data sets with GPS coordinates, NREL’s processing routines join data points to the road network, link U.S. census and other spatial data layers, and add road-grade information. For the transit section, NREL pairs raw transit data with general transit feed specification data to provide information about the routes available when a given study or survey was conducted.

Researchers and academics from around the world tap into the TSDC’s rich transportation data for diverse research studies and analyses, as described in the more than 230 journal articles, conference papers, and technical reports listed on the TSDC’s publications webpage.