Analyzing the impact of 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 quality requirements, the provider needs to make real-time adaptations to its routes and schedules, restoring feasibility at an additional cost. The objective of this work is to quantify the sensitivity of integrated routing solutions with respect to delays on the public transport network. To this end, the travel times of the public transport are modeled as stochastic, time-dependent travel times. The impact of different types and extents of delays on the operational efficiency of the system is quantified.