Trials network analysis and path optimization in the western Italian Dolomites

The purpose of this work is the development of an automatic procedure for the analysis and optimization of paths on the Trentino, Italy, mountain trails network. The Tridentine Alpinist Society (Società degli Alpinisti Tridentini, SAT) provides a map of the Trentino mountain trail network in the KML, SHP and GPX formats with ODbL license. The availability of this map allows the GIS analysis of the topological features and environmental aspects of the graph of the corresponding network. The evaluation of the traveling times for each path is carried out according to the Schweizer Wanderwege formula, which links walking speed to the slope, but with the possibility of adding reductive coefficients of the speed as a function of the accidentality of the terrain. The estimated time for each trail has been verified by comparing it to the empirical travel time published by the SAT. After modifying the network topology by breaking lines at intersection points. it has been possible to compute the traveling time for each trail section. Traveling times in the two directions, length and height difference has been associated to each trail section, to be used as “costs” in path minimization. Points of interest have been added to the network to be used as nodes, i.e. points of departure and / or arrival of routes or intermediate points stop. These points have been associated with relative "cost" values of the average stay times. Simulations have also been done on the network graph in order to identify the minimum paths: starting from a parking, touching some significant points (shelters, mountain huts, panoramic sites, ...) and returning to the initial parking lot. As an element of "cost" they have been used the planimetric distance, the travel time or the height difference, with or without stopping times on the nodes. The whole procedure was automated through a Python script that performs processing in GRASS GIS. Estimated traveling times are in good agreement with empirical times and the network analysis and path minimization have shown that the minimum cost path can be very different depending on the cost choice. In particular, for mountain paths, shortest paths are different whether the distance, the traveling time or the total height difference is minimized.