Developing Guidance for a Corridor Level Vehicle Occupancy Rate Data Collection Program

Moving Ahead for Progress in the 21st Century Act (MAP-21) and Smart Scale continue to foster congestion management initiatives, many of which emphasize more person movements than vehicle movements; therefore,vehicle occupancy data are becoming increasingly important. Presently there are two data sources for obtaining the number of persons per vehicle: the American Community Survey (ACS) administered by the U.S. Census Bureau, and the National Household Travel Survey (NHTS) administered by Federal Highway Administration (FHWA). The former only provides occupancies for one trip purpose (the work trip) and is updated every one to five years depending on the jurisdiction’s population; the latter provides occupancies for many trip purposes but is only updated roughly every 7 years. Neither source provides corridor-specific occupancies. In order to calculate MAP-21 PM3 measures, there is a need to have detailed corridor specific occupancy rate data by time of day (am peak, mid-day, pm peak,weekend) and vehicle types (car, bus, and truck). The objective of this research is to establish guidance on how to collect, where to collect, when to collect, why to collect, and what to collect so that the Virginia Department of Transportation (VDOT) Transportation Mobility Planning Division can build an occupancy rate data collection program similar to VDOT's Traffic Engineering Division’s short-term traffic count program. The research and resulting guidance will provide VDOT with methodologies to assess carpooling, commute-shed activity patterns, and impacts of congestion management strategies at the corridor level. Consequently, MAP-21 and Virginia Smart Scale performance measure requirements can be realized.