In 1999, the Dutch professional magazine on public transport, `OV Magazine', started a discussion about what type of service model would enable higher frequencies between the main stations of the cities, compared with the `classic' hierarchical service model. In the presented concepts, some direct connections between smaller stations would disappear. It can be questioned, however, whether this concept is suitable given the structure of Randstad Holland, with many smaller network nodes and stations serving smaller peripheral business districts. In this paper, the possibilities for increasing frequencies between the larger stations are studied, given the hierarchical service model and heterogeneous traffic. A system with three service types, with the middle level having a double frequency compared to the lowest level, appears to minimise the capacity usage per train. This concept has been elaborated for Randstad Holland. The middle level, the `Delta Metropolitan Express', provides a connection between the larger stations each 10 minutes. Hence, the service frequency can be increased for many connections. (A)
Abstract