Evaluating the structure and use of hiking trails in recreational areas using a mixed GPS tracking and graph theory approach

Recreational trails encourage numerous outdoor leisure activities in a variety of urban, rural, and natural environments. Understanding the way trails function is crucial for the designers and managers of recreational sites to balance the needs of visitors and site capacities. This paper presents a new approach to evaluate the structure and use of hiking trails by combining GPS tracking and analytical methods based on graph theory. The study is based upon empirical data (N = 482 GPS tracks) collected in the Lobau, which is part of the Danube Floodplains National Park in Austria. The physical structure of trails (structural network; undirected graph) and their usage (functional network; directed graph) were analysed using a graph theory approach. The network coherence (connectivity indices: β, γ, α), the movement direction at path segments and the relative importance of network nodes (node centrality measures: degree, closeness, betweenness) were calculated. The Lobau trail network is not evenly used by park visitors. Therefore, the calculated parameters differ between the structural and functional networks. From management perspective the results obtained for the functional network are particularly important. 61% of recreational use (hiking) concentrates on designated trails, 21% on non-marked paths and 18% is off-trail use. In most cases the location of signposts and information boards in the Lobau corresponds with the highest node centrality measures in the functional network (degree and betweenness). The proposed methodology can be easily adopted for the evaluation of any trail network in outdoor recreational sites.