Delay resistant timetabling

In public transport punctuality has prominent influence on the customers’ satisfaction. Our task is to support a management decision to optimally invest passengers’ nominal travel time to secure the nominal schedule against delay. For aperiodic scheduling we clarify the notion and use of a fixed amount of time supplements, so-called buffers, both theoretically and by realistic examples. The general tool to solve such optimization problems is a sampling approach. We show how this approach is mathematically justified. As its applicability to large networks is limited, we show an efficient alternative for the case of series-parallel graphs. For periodic timetabling we propose two heuristic approaches to ensure a certain level of delay resistance at the least expense of slightly increased nominal passengers travel time, and analyze in detail their advantages and drawbacks.