Least-Cost Path Routing for the 20" ANOH Pipeline

Poorly documented geology, difficult terrain, long distances, and abrupt bends all push up the cost of building natural gas pipelines. This study set out to find a better right-of-way for the 20-inch ANOH gas pipeline before mainline construction, using GIS rather than paper maps.

Environmental, engineering, man-made, natural, socio-cultural, and economic criteria — land use and land cover, slope, roads, rivers, existing rights-of-way, and geology — were built from Landsat 8 imagery, SRTM elevation data, and national survey datasets. The Analytic Hierarchy Process weighted each criterion through pairwise comparison, and the weighted overlay produced a discrete cost surface. From there, cost-distance and backlink rasters drove a least-cost path search between the documented source and destination.

Both optimal routes came out shorter than the existing 28 km right-of-way — 22.42 km and 21.78 km — and avoided every river, road, and pipeline crossing the existing route makes. That matches the 15–30% savings the literature attributes to GIS-based least-cost routing, and supports using the method as a standard preliminary step in route selection.