Decision Support for Dimensioning an Innovative Rail-Road Transport System

This paper proposes an optimization algorithm to support decision makers in the dimensioning of a new type of public transport service. In particular, vehicles capable of traveling on both rail and road are exploited to revitalize capillary railway lines, characterized by low demand but very high societal impact. To support decisions on infrastructure modifications and fleet size, we propose an algorithm based on the solution of a mixed-integer linear programming model. In particular, the infrastructure modifications considered consist in the construction of road-type sidings on the existing railway line, to allow vehicle crossing. We assess the performance of our algorithm on a real case study: the line joining the cities of Limoux and Quillan, in France. The results highlight how investing in siding construction can indeed improve the regularity of the timetable that can be planned. However, depending on the available fleet and the desired frequency, they may not be strictly necessary.