Specification of rolling stock power capacity

In mass transit systems, the train journey time is a key performance factor. The journey time can be split into dwell (waiting and access) time and travelling time. The travelling time, when operating under a full line speed, depends on the traction power capacity of the train. In order to minimise the travelling time the train ideally should; accelerate at the maximum permissible limit at the beginning of the journey until a full line speed is reached, the full line speed is maintained until approaching the next station then the maximum braking rate is applied. To achieve these characteristics, many new, or renewal, mass transit projects were resorted to satisfy this criterion by specifying a large power capacity for the rolling stock. The question is how large a power capacity of the train is required, and is there a limit which restrains the project engineer/designer? These subjects are discussed in this paper