Reliability is one of the key indicators of level of service for public transport. In urban areas several sources lead to poor schedule adherence. If reliability is low, passengers will experience longer waiting times at stops and during transfers. Because of the relatively short journeys in urban areas, the increase of waiting times is significant. Next to the increased travel times, unreliability also results in less comfort and a smaller chance of having a seat, because of bunching of vehicles. Besides, travelers dont appreciate uncertainty during their trip. Normally, reliability issues are analyzed and improved at the operational level of public transport. The hypothesis in this research is that already during the strategic and tactical planning phases reliability can be taken into account and be improved. This paper uses a case study of the tram lines in The Hague in The Netherlands to show the effect of unreliability for passengers. An analysis is made of actual travel time components for a better understanding of the problem. Solutions during the planning phases are suggested and analyzed. It is shown that using other parameter values in timetable planning than currently applied, leads to less extra waiting time for travelers. The effect of taking reliability explicitly into account when designing line length, stop spacing and coordination strategies is analyzed as well. This research thus demonstrates that improvements in reliability can already be achieved during the planning phases of public transport.
Abstract