The Method and Conditions for Completing Soft Coupling of Two Separate Train Sets in Motion

Abstract

Soft coupling is a conceptual system in which two or more train sets on the same railway track can run like one long mechanically coupled train set, with very little space between the adjacent train sets. It is expected to open up possibilities for the realization of highly flexible and improved rail services. However, it is known to be very difficult for two separate train sets in motion to complete soft coupling, i.e., for the distance between these train sets to become zero. In the method we proposed in our previous papers, the time required for the completion may be infinite, because the train set that follows another must run faster when approaching the train set in front. This paper focuses on the method of completing soft coupling within finite time. We show that such a method can be proposed under the following set of preconditions: (1) infrastructure enabling the removal of the conservative safety concept of railway signalling called `brick wall' assumption, (2) simultaneous control of two train sets through a very secure wireless communications link, and (3) high-accuracy control of the deceleration of train sets.