Validation and Sampling of Automatic Rail Passenger Counters for National Transit Database and Internal Reporting at TriMet

This paper presents findings from an evaluation of the accuracy of automatic passenger counters (APCs) on the Tri-County Metropolitan Transportation District of Oregon's (TriMet's) light rail vehicles. APC boarding and alighting counts were compared with manually recorded counts. Overall, the APCs tended to undercount boardings and overcount alightings. Thus, correction factors will be needed for use of APC-recovered data for National Transit Database (NTD) and internal reporting. The paper also describes the sampling procedures employed by TriMet for NTD and internal reporting, in which sampled trips are linked to archived APC data records.