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

S. Biba, K. M. Curtin, G. Manca
2010 International Journal of Geographical Information Science  
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
more » ... 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. transit routes in order to perform planning and operational functions (Dallas Area Rapid Transit 1998, Dallas Area Rapid Transit 2002, Federal Highway Administration 2002 , Wu and Hine 2003 . Unfortunately, since the methods used within the GIS consistently overestimate the population with access to transit (O'Neill et al. 1992 , Zhao et al. 2003 , planners and decision makers lose confidence in the ability of GIS to provide reliable answers to policy questions, particularly those questions concerning the changes in accessibility that will be achieved by changes in service. In order to address this concern, this research presents an improved method for determining the population with walking access to transit facilities -the parcel-network method. This method employs high-quality cadastral data with network functionality to determine walking distances to transit facilities in order to more precisely estimate the population with access to transit. As is shown below, this method provides more conservative population estimates than the methods currently in use, it produces summary statistics and output data sets that cannot be generated through the other methods, and it provides a more flexible basis for further refinement of the transit forecasting and planning process. Although our method is designed for a transportation application, the novel integration of cadastral data with network analysis in our method holds promise for research in many areas of geographic information science. Section 2 reviews the literature in this area, followed by a description of the steps involved in building and using the parcel-network method. This is followed by an application of this new method using a set of data from the north Dallas region. A quantitative comparison of the results is made for the buffer, network-ratio, and parcelnetwork methods. Additional research opportunities are discussed in Section 6. Literature review The literature concerning the determination of transit service areas falls into two main areas. First, there is research concerning the existing methods for determining transit service areas, specifically the buffer (or area-ratio) method and the network-ratio method. Second, all methods for determining transit service areas depend on estimating walking distance for transit users. We review both of these research areas below. 2.1. Existing methods for determining transit service areas
doi:10.1080/13658810802646679 fatcat:cqjbuqmgrnh3ppot2c2jikhy4u