Flexible services for people transportation: a simulation model in a discrete events environment

The realization of innovative transport services requires greater flexibility and inexpensive service. In many cases the solution is to realize demand responsive transportation system. A Demand Responsive Transport System (DRTS) requires the planning of travel paths (routing) and customer pick-up and drop-off times (scheduling) according to received requests. In particular, the problem has to deal with multiple vehicles, limited capacity of the fleet vehicles and temporal constraints (time windows). A DRTS may operate according to static or dynamic mode. In the static setting, all the customer requests are known beforehand and the DRTS solves a Dial-a-Ride Problem (DaRP) instance, to produce the tour of each bus, respecting the pick up and delivery time windows while minimising the solution cost. In the dynamic mode, the customer requests arrive over time to a control station and, consequently, the solution may also change over time. In this work, we address a Demand Responsive Transport System capable of managing incoming transport demand using a two-stage algorithm by solving a DaRP instance. The solutions provided by the heuristics are simulated in a discrete events environment in which it is possible to reproduce the movement of the buses, the passengers' arrival to the stops, the delays due to the traffic congestion and possible anomalies in the behaviour of the passengers. Finally, a set of performance indicators evaluate the solution planned by the heuristics. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Organizing Committee.