Resumen
Among the most effective actions to promote functional cycling, i.e., cycling as a mean of transport, infrastructure design and planning are major topics. Much less attention has been dedicated to the design and deployment of bikeways devoted to recreational cycling, despite the role of cycle routes in promoting cycle tourism, and the effectiveness of cycle tourism in fostering sustainable and environmentally friendly economic growth, in addition to encouraging healthy life styles. In this paper we contribute to fill this gap: we propose a quantitative based methodology for designing a cycle-tourist network infrastructure intended to provide local administrators with a quantitative based decision support tool to optimally exploit the scarce public funding devoted to the project deployment. We consider as a case study the data of the Trebon region, in South Bohemia. Given the local points of attractions and a set of potential links which can be turned into cycle pathways against a little investment in addition to a set of links already fit for cyclists, a network of cycle routes that interconnects a set of pre selected gates must be designed, so that the total link refurbishment cost is budget compliant and the attractiveness of cycle itineraries from gate to gate supported by the infrastructure is maximized. In previous studies we showed how to compute a resource-constrained optimal path from origin to destination, which maximizes a utility function related to the attractiveness of the arcs and nodes along the path. In a later work we generalized the problem to the case of multiple users with different utility functions that must share the same monetary budget. Building on these results, in this paper we propose a heuristic solution approach for the network design problem, where routes connecting several origin destination pairs have to be designed, yielding a connected infrastructure which allows for further itineraries. We exploit the ability of modern solvers to quickly find solutions to the single-pair single-user aforementioned case to generate a pool of promising paths from gate to gate, according to different preferences and constraints. In a second step, the network is built by solving a second combinatorial optimization problem which selects a path for each pair of gates from the pool, to yield a budget compliant connected infrastructure. Finally, a post optimization step deletes redundant links, if any. The solution approach is validated by an experimental campaign performed on realistic data for the Trebon zone, in Southern Bohemia.