Determining transmission line path alternatives using a valley-finding algorithm

Abstract

Since new (Power) Transmission Lines (TLs) can have a long-term effect on the makeup of a landscape and on the human living space, it should be expected that the route of any new TL will be based on objective criteria that take into account the views of the public. Geographic Information Science (GIScience) provides powerful tools that assist in the determination of feasible locations for new TLs based on objective criteria and georeferenced data by combining methods from Multi-Criteria Decision Analysis (MCDA) and Least Cost Path (LCP) analysis. If such an approach is applied, the LCP analysis usually yields one optimal result. However, stakeholders and decision-makers prefer to compare multiple distinct path alternatives in order to find a solution that will be acceptable to as many stakeholders as possible. We have developed a method that calculates spatially distinct and Pareto optimal path alternatives based on the same cost surface using an algorithm for determining valleys on a Digital Elevation Model (DEM) to determine local low-cost points, which were then connected to a network graph by geometrical rules. Finally, we selected all non-dominated path alternatives that represented Pareto optimal conditions regarding a specific main objective. We then asked ten expert stakeholders to cross-compare the calculated path alternatives and assess our novel method. The concept of applying linear programming to obtain Pareto optimal path alternatives yielded routings that were mostly preferred over the LCP and had a greater likelihood of being realized than the results obtained by conducting the LCP analysis. The stakeholders determined the method's key concept to be useful and assert it a high potential to support planning, matter-of-fact argumentation, and discussions about TL routing.