A new method for determining the population with walking access to transit

The use of geographic information systems in determining transit service areas has not progressed far beyond simple buffering operations even though there is widespread capability to analyze network walking distances in conjunction with demographic, cadastral, and land-use data sets. This article presents a method for determining the population with walking access to bus stop locations using the spatial and aspatial attributes of parcels and the network distances from parcels to bus stop locations. This parcel-network method avoids the well-known and unrealistic assumptions associated with the existing methods and reduces overestimation of the population with access to transit, resulting in improved spatial precision and superior inputs to transit service decision-making processes. Comparisons of the parcel-network method, the buffer method, and the network-ratio method are made in a study area within the Dallas metropolitan area. The novel integration of cadastral data with network analysis in our method holds promise for research in many areas of geographic information science.