Restoring time synchronization in response to delays in an integrated mobility system

Abstract

In many Western countries, governments are currently implementing an innovative demand-driven mobility policy. Providers of collective door-to-door transport, called dial-a-ride services, are increasingly invoked to replace unprofitable public transport in rural areas. This requires an integrated mobility system in which a user’s trip may consist of a combination of dial-a-ride services and regular public transport. To optimally integrate both systems from an operational point of view, dial-a-ride providers need to solve a challenging routing problem, in which their flexible vehicle routes should be synchronized to the timetables of the remaining public transport services. However, the practical feasibility of such an integrated mobility system strongly depends on the reliability of the transfers. Dial-a-ride providers should adequately respond to structural or occasional delays of the public transport. Whenever such delays are likely to cause broken connections or violated time constraints, the provider needs to make real-time adaptations to its routes and schedules. For this purpose, a new integrated scheduling procedure is proposed which aims at restoring feasibility or, when this is impossible, minimizing the inconvenience (i.e. violations of time windows or maximum ride times) faced by the customers. The proposed scheduling procedure is embedded into a dynamic LNS routing algorithm, allowing to quantify the sensitivity of integrated routing solutions to different types and extents of delays on the public transport network.