Stop Aggregation Model

Abstract

The development and the application of a stop aggregation model (SAM) for a transit network based on Google's General Transit Feed Specification (GTFS) are detailed. The use of GTFS has been drawing attention in the public transit planning arena. A SAM is proposed to explore how to use this innovative data source in a transit network. The hypothesis is based on the fact that transit users' activity may not originate from or be destined to an individual stop per se. Rather, the activity is associated with a specific location in the vicinity of the stop, and this location may be covered by several adjacent transit stops. Therefore, the goal of a SAM is to define a generalized definition of a stop that more closely matches the nature of locations that serve as passenger origins and destinations. To define an aggregate area around a transit stop or station, three parameters are investigated: distance or proximity, text in the stop description, and the catchment (service) area. These aggregated stop groups can be represented as a single node in the transit network, depending on the level of aggregation desired. A case study of the Minneapolis–Saint Paul metropolitan area in Minnesota is performed with GTFS data from Metro Transit. A SAM can be practically applied in estimating aggregate-level origin–destination flows and linking with onboard survey data.