The impact of scheduling on service reliability: trip-time determination and holding points in long-headway services

This paper presents research on optimizing service reliability of long-headway services in urban public transport. Setting the driving time, and thus the departure time at stops, is an important decision when optimizing reliability in urban public transport. The choice of the percentile out of historical data determines the probability of being late or early, while the scheduled departure time determines the arrival pattern for travelers. A hypothetical line and a case study are used to determine the optimal percentile value for long-headway services without and with holding points. If no holding points are applied, it is shown that the 35-percentile value minimizes the additional travel time to 25 % of the reference situation. In the case of holding, two holding points combined with a 30-60-percentile value yield the best performance: a further reduction of the additional travel time with 60 %.