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Systematic train delays

evaluated

After passenger boarding, trains sometimes have to wait in the station until the timetable permits departure. Otherwise this time could be exploited for energy efficient driving. The strategy of systematic train delays is intended to exploit this “lost” time buffer.

Technology field: Energy efficient driving

General information

Description

After passenger boarding, trains sometimes have to wait an additional period of time in the station until the timetable permits departure. This is a waste of precious time given the importance of time buffers for energy efficient driving. The strategy of systematic train delays is intended to exploit the time periods usually wasted in stations. The train is driven according to a “shadow” schedule which is identical to the “public” schedule at the main stations but slightly delayed at the intermediate stations. The driver can immediately leave the station after passenger boarding and has more buffer time for energy efficient driving strategies. The delays (< 2 min) can be chosen small enough in order not to bother passengers. This strategy is presented in detail in Euro Transport Consult 1997. In order to raise customer acceptance, the following modification is proposed: Instead of consciously delaying train arrival as foreseen by the above concept, the delay could be shifted to train departure. This is achieved by reducing standing times in stations: If passenger boarding is quick, train leaves in time, otherwise departure is slightly delayed. This modification of the concept could raise acceptance since punctual train arrival is more relevant for service quality than punctual train departure.

General criteria

Environmental criteria

Impacts on energy efficiency:

Energy efficiency potential for single vehicle: (no data)

Energy efficiency potential throughout fleet: (no data)

The additional time buffer provided by systematically delaying trains at some stops will have an especially strong effect on energy efficiency if the original timetable is close to minimum running time. This may be seen in the following diagram showing minimum energy demand against running time. Although the diagram refers to a specific Swiss line, the characteristics of the plot is general.

Figure 1: Minimum energy demand against running time for a specific Swiss line

demand time plot.gif

Source: IZT based on Meyer et al. 2000

In the situation illustrated in the diagram a shortest time driving strategy will lead to a running time of ~ 16,5 minutes. While between 16,75 and 17,75 minutes the energy difference will be of about 3 Wh/tkm, the one between 17,75 and 18,75 will be of 0,5 Wh/tkm only.

This illustrates that a general estimate of energy savings through systematically delayed train is not possible and that the biggest effect will be achieved for timetables that are originally very tight (small time buffers). Even in these cases it has to be kept in mind that the energy savings can only be realised for a small portion of the trips if no (additional) train delays occur and rapid passenger boarding allows for short stops at stations.