Public Transit Ridership Used in the Transportation Services Index

Friday, November 22, 2024

Return to all data sources used in the Bureau of Transportation Statistics’ Transportation Services Index.

General

The public transit component of the Transportation Services Index includes monthly data from the American Public Transportation Association (APTA) and monthly data from the Federal Transit Administration’s (FTA's) National Transit Database (NTD). Data for the years prior to 2010 are from APTA while data for years 2010 and later are from the NTD. BTS uses data from the NTD, because the data are available in a more timely fashion than from APTA. BTS selected 2010 as the first year to use the NTD, because 2010 corresponds to the year when collection for the NTD stabilized. Both sources provide the number of unlinked passenger trips for transit.

Transit modes, include, among others, bus, trolleybus, vanpool, jitney, and demand response service; and heavy rail transit, light rail transit, commuter rail (including Amtrak contract commuter service), automated guideway transit, inclined plane, cable car, monorail, aerial tramway, and ferryboat.

Methodology

Congress established the NTD to be the Nation’s primary source for information and statistics on the transit systems of the United States. Statute requires that recipients or beneficiaries of grants from the FTA under the Urbanized Area Formula Program (§5307) or Other than Urbanized Area (Rural) Formula Program (§5311) submit data to the NTD. To account for public transit services not reported to the NTD, APTA expands NTD data by mode in stratified categories of similar systems based on population and other characteristics according to vehicles operated.

Collection

FTA requires predominantly large and medium-size transit agencies to report annual unlinked passenger trips, which FTA includes in the NTD. Monthly data collection began as a pilot program in 2002. Over time, most transit properties developed new internal data collection and processing methods to meet the new requirements. These developments, combined with the implementation of more sophisticated validation checks by FTA, have resulted in more complete and accurate data in more recent years.

All ridership data reported to FTA relate to trips, not to people, because that is how transit agencies collect and report data. The use of passes, transfers, joint tickets, and cash by people transferring from one vehicle to another, one transit mode to another, and from one public transit agency to another makes it difficult to count people. Boardings (unlinked passenger trips) can be counted more accurately. At the largest public transit agencies, even boardings may be estimated for portions of the ridership.

The majority of people using public transportation take two trips per day (one to a destination in the morning and one home in late afternoon or evening). A small portion, perhaps 5%, makes only one trip. Larger portions take more than four trips per day. At most agencies (10% to 30%) of riders transfer to a second transit vehicle to reach their final destination.

FTA does not collect data from all transit agencies. To account for public transit services not reported to FTA and hence not included in the NTD, APTA estimates U.S. transit totals by supplementing the NTD with survey data collected from APTA transit system members and other undisclosed sources.

Data reported in the NTD and by APTA are for “report years”. A report year is each public transit agency’s fiscal year that ends during a calendar year. For example, report year 2018 contains agency data from the fiscal year that ended in 2018.

Data Quality Questions

Coverage/Completeness

After the close of a month, transit properties have one month to compile and submit data to the NTD. Therefore, 30 days elapse from the end of the month until transit agencies submit data. Some data may be missing for the most recent month if a transit agency failed to report data on time. Once a transit agency submits data, FTA reviews and analyzes its completeness and reasonableness. Transit agencies may revise their data at any time during the calendar year reporting cycle. These revisions will be reflected in subsequent release of the monthly data base.

FTA requires agencies to report a 100 percent count of unlinked passenger trips if the data are available and reliable. However, many agencies do not have the technology or the means required to perform a 100 percent count. (This is because the reporting of unlinked passenger trips requires an accurate count of the number of transfers made by passengers.) In other cases, the service is too complex to allow a 100 percent count. In these cases, FTA allows reporting based on sampling. In general, FTA does not know what method agencies use to determine unlinked trips, i.e., if it is based on sampling or a 100 percent count.

APTA releases a quarterly ridership report based on the NTD and other data sources approximately 60-75 days after the end of the quarter. The data in the report pertain to public transportation agency services operating directly operated (DO) and/or purchased transportation (PT) modes. There report includes monthly totals for the current and past two calendar years.

Is this data source a frame or sample?
See above.

Does the sample cover the entire frame? Or is there some group that is missing or underrepresented in the sample? For the excluded group, what percentage of the total do they make up?
See above.

Timeliness

Are the data available monthly?
Yes.
How soon the data are available after the month is over?
After the close of a month, transit agencies have one month to compile and submit data to the NTD. Therefore, 30 days elapse from the end of the month until agencies submit data. Some data may be missing for the most recent month if a transit agency failed to report data on time.
Are the data easy to access and use?
Yes.
Website: https://www.transit.dot.gov/ntd
Are the microdata available for use?
Yes. https://www.transit.dot.gov/ntd

Accuracy

Are there duplicate records?
No. Once FTA receives data, FTA reviews and analyzes completeness and reasonableness.
Are there outliers in the data?
No.
Are data missing for individual records? If so, how are they identified?
See above.
How accurate are the key fields (i.e., miles or trips)?
The key field is unlinked passenger trips. Accuracy depends on the individual agency and the data collection system used.
Are variances available for this data source? If so, what method was used to calculate variances?
No.

Comparability

Are the data comparable over time within the data source? If not, can data be made to be comparable (i.e., combining two data series)?
The data for the years before 2010 are from APTA. The data for 2010 and after are from the NTD. The two sources are comparable although APTA totals tend to exceed those in the NTD. APTA supplements the NTD with data from other sources to capture transit agencies that do not report to FTA and hence are not part of the NTD.

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