Country: Canada
Key Area: Transportation
Services: Asset Management,GIS,Transportation Asset Management

GIS is particularly effective in support of transportation corridor studies where a number of data layers or themes are analyzed. An example is data highlighting the impact of  proposed highway alignment alternative routes. Using GIS can improve efficiency gains with the use of imbedded GIS spatial analysis and mapping tools to optimize project workflows. It can also improve the quality of deliverables through a more thorough analysis of multiple alignment options, improved map products, better support for public presentations, and the preparation of value added digital mapping project files for subsequent client use. One specific project example is the determination of alternative route corridors for a new section of the Trans Canada Highway in New Brunswick. Use of GIS was particularly effective for this study due to the availability of high-quality digital topographic and property mapping for the project area, including digital elevation models. The various layers included areas of excessive slope, buildings, wetlands, land cover, and heritage sites. Other constraint areas such as wildlife habitat areas, environmentally sensitive areas, archaeological sites were added through field survey and digitization from hard copy maps. More than 100 constraint layers were developed to support the corridor analysis.

A GIS-based polygon overlay analysis methodology was used to evaluate alternative corridors and individual alignments within each corridor. Buffers were created around each alignment to create a polygonal corridor feature, and these polygons were then overlain on each constraint area to determine areas of impact. These were weighted according to constraint severity and accumulated across all constraints to develop a total impact score for each corridor and alignment option. These total scores were ranked, and the team sought to select a solution that minimized the impact of the highway on the surrounding landscape.

GIS tools were also used to create improved hard copy map outputs for the client and in support of public presentations.