Source: American Public Transportation Association (APTA) (private nonprofit organization).
The TSI uses monthly American Public Transportation Association (APTA) data for the transit component of TSI. APTA is a nonprofit association of transit systems and commuter rail operators, transit associations, state departments of transportation, and other organizations. According to APTA, over 90 percent of persons using public transportation in the United States and Canada are served by its members. The number of unlinked passenger trips is the measure used for the TSI.
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.
APTA data for the reference year is initially published as preliminary data. Some agencies routinely revise their data in succeeding quarters and the following year.
Some transit agencies do not report data for all modes; occasionally an agency will report only two of the three months of the quarter data for a mode. APTA may exclude such modes when calculating the extrapolated totals.
The U.S. Federal Transit Administration requires that annual unlinked passenger trips and passenger-miles data be collected or estimated by the predominantly large and medium-size transit agencies participating in its National Transit Database (NTD). APTA supplements this with monthly data, which includes some small transit agencies not in the NTD.
All ridership data reported relate to trips, not to people, because that is how data are collected and reported. 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. APTAs best estimate is that the number of people using public transportation on any day is about 45% of the number of trips reported. Saturday ridership is often about 50% of weekday ridership, and Sunday ridership may be only 25%.
APTA transit ridership data are obtained from APTA members. APTA reporting is voluntary, but virtually all of the larger and many medium-sized transit agencies report. Normally, all heavy rail and trolleybus agencies participate, and virtually all light rail and commuter rail agencies do report. Large extrapolations are necessary for bus, demand response, ferryboat, vanpool, and the minor rail modes.
APTA ridership data are unofficial, preliminary data reported by about 250 transit agencies that are extrapolated to get a national estimate. The data are reported monthly, so the combination of months adds up to a calendar year total. These monthly data are published quarterly on the APTA website. First quarter data are available about July 15 each year; second quarter about October 15; third quarter about January 15; and fourth quarter about April 20. There are no other sources for getting the monthly passenger-miles. Passenger-miles data are only collected and reported annually in the National Transit Database.
Data Quality Questions
This is a voluntary response survey. It includes all of the largest transit agencies and covers about 90% of the total ridership. This ridership includes about 250 of the 600 transit agencies that are members of APTA. APTA data are updated monthly. Data can be cross checked against the NTD on an annual basis.
- Is this data source a frame or sample?
The data source is a sample.
- 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?
The ridership survey is conducted among APTA members. All reporting is voluntary, though APTA does receive reports from virtually all the larger and many medium-sized transit agencies. Normally, all heavy rail and trolleybus agencies participate, as do virtually all light rail and commuter rail agencies. APTA data represent about 90% of the estimated national total.
- Are the data available monthly?
No, the data are monthly, but are published quarterly.
- How soon the data are available after the month is over?
Data are released quarterly; usually with a lag of 4 to 6 months if data come from the APTA web site.
- Are the data easy to access and use?
- Are the microdata available for use?
Each year's file contains that year and the preceding year. Thus, 2003 includes both 2003 and revised 2002. 2002 contains 2002 and revised 2001, 2001 contains 2001 and revised 2000, etc. These files contain the individual pieces of data that are collected from each transit agency. [s21]
- Are there duplicate records?
No. APTA performs a primary check of the data and contacts individual agencies about questionable data.
- Are there outliers in the data?
- Are data missing for individual records? If so, how are they identified?
Some transit agencies do not report data for all modes; occasionally, an agency will report only two of the three months of the quarter for a mode. Because of these problems, APTA has developed a procedure to ignore such modes when calculating the extrapolated totals. The period for reporting the data to APTA is 90 days. If the data are not reported within the time period, APTA will estimate the data based on the previous data it has received from that agency.
- 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. (See further discussion under Detailed Description of Methodology.)
- Are variances available for this data source? If so, what method was used to calculate variances?
- 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)?
Although there is about a 5% difference in the agencies and modes reported from year to year, the data should be comparable since the same extrapolation procedure is used.
Other Questions and Important Information
- Is sufficient documentation available for the data source?
The definitions for public transportation transit can be found either in the Public Transportation Fact Book or http://www.apta.com/research/info/define/.
- Data dictionary:
Unlinked passenger trips are the number of passengers who board public transportation vehicles.
- Detailed description of the methodology:
Some rail systems have complete, real-time data, using automated fare collections systems. Others have complete but not real-time data. Demand response systems typically have complete data based on trip requests. Many systems, especially most bus systems, rely on periodic driver surveys. The results of these surveys are impacted by which routes are surveyed in a given month, driver accuracy in reporting, accuracy of reporting of transfers, and other things.
- Operational details:
Data are reported in thousands, in PDF file format. The latest three years' data are preliminary.
- Estimation methods:
For small agencies, it is easy to report the actual ridership, for some large agencies, the number of boardings would be estimated for the portion of the ridership. If the agencies did not report 3 months of data for that quarter for a transit mode, the data would be ignored for that mode.
- Are other sources available for the same data?
Monthly data are not available elsewhere at this time.
- Who is the contact for the data source?
American Public Transportation Association, http://www.apta.com.