Control of Public Transportation Operations to Improve Reliability

Abstract

RandstadRail is a new light rail system between the cities of The Hague, Rotterdam, and Zoetermeer in the Netherlands. During peak hours, the frequency on some trajectories is about 24 vehicles an hour. To deal with these high frequencies and to offer travelers a high-quality product according to the waiting times and the probability of getting a seat, the operator designed a three-step philosophy for controlling the system. The first step is to prevent deviations from occurring: the infrastructure is exclusively right-of-way as much as possible, and at intersections RandstadRail gets priority over the other traffic. RandstadRail stops at every stop and never leaves before the scheduled time. The second step in the philosophy is to deal with deviations by planning additional time in the schedule at stops, trajectories, and terminals. Small deviations can be solved in this way. The final step is to get vehicles back on schedule and is performed by the traffic control center: it has a total overview of all vehicles and can respond to disturbances, such as by slowing down vehicles near a delayed vehicle. Major disturbances may be experienced as a result of the rerouting and shortening of lines. RandstadRail has been in operation since 2007. The actual data on its performance were used to analyze the actual effects of the control philosophy. It is shown that because of the measures applied, the variability in trip times has been reduced, while punctuality has increased. This leads to a higher level of service, creating shorter trip times and a better distribution of passengers among the vehicles.