A link-focused methodology for evaluating accessibility to emergency services

This paper considers the development of a new measure for evaluating accessibility to emergency services via a road network called critical closeness accessibility (CCA). CCA quantifies the relative importance of each link in a roadway network with respect to its system-wide contribution to emergency service accessibility and is based on the network science/graph theory concept of closeness. CCA is a link-focused measure that used to evaluate accessibility on a link-by-link basis and can be used for disconnected networks. We introduce a relative importance-based weighting approach for both origins and destinations that can be applied to different types of nodes including generic link endpoints that represent individual intersections and roadway segments in GIS-based roadway maps as well as to physical locations. CAA offers a unique approach for evaluating accessibility that accounts for the spatial distribution of emergency service locations, the topology of the road network, and the engineering characteristics of the road network such as road types, capacities, volumes, and travel speeds. (C) 2013 Elsevier B.V. All rights reserved.