Analytic Hierarchy Process and Geographic Information Systems to Identify Optimal Transit Alignments

Honolulu, Hawaii, like other urbanized centers, is struggling to solve problems of transportation supply and demand. One proposed solution is construction of a fixed-rail transit system along the east west corridor, to connect the western part of the county to the downtown work zones. Setting up a transit alignment that meets technical, social, economical, and environmental considerations is a challenge. This study coupled the technologies of analytic hierarchy process (AMP) and geographic information systems (GIS) to assist in the decision-making process of determining optimal transit alignment between the competing Salt Lake and Airport alignments in Honolulu. The goal of the AHP structure was to determine the location for the transit alignment: technical, social, economical, and environmental considerations are the criteria, and suitability levels are the alternatives. A uniform grid structure was developed: thematic maps related to the independent variables were converted into a 0.1-square-mile grid map. The grid data and survey results were entered into the AHP structure to produce an index of suitability that could be plotted in the GIS environment to indicate optimal alignments for the rail transit system on the basis of public preferences and technical criteria.