Ridership Accuracy and Transit Formula Grants

Abstract

The accuracy of annual unlinked passenger trips reported to the National Transit Database (NTD) at the agency level is examined by using a two-step approach. The first step compares ridership reported to the American Public Transportation Association (APTA) with ridership reported to NTD. NTD ridership can be as high as 50% more than APTA ridership, and such significant positive deviation exists persistently over time across many agencies. The second step explores potential sources of these deviations by examining their components. Random errors, including both sampling errors and some of the nonsampling errors, do not help explain these one-sided deviations, nor do occasional annual adjustments, such as special-events ridership in the NTD ridership. Much of this deviation appears to be attributable to systematic nonsampling sources that result from undercounting in direct counts, from unintentional biases in procedures, or perhaps from intentional manipulation. Although mechanisms and incentives exist for these sources, there is little evidence for any one specific source. How systematic errors could affect the allocation of two formula grants to Florida transit agencies—the Urbanized Area Formula Grant Program and Florida's Transit Block Grant Program—is quantitatively examined. A strategy for reducing systematic errors is also discussed.