More than 20 years have passed since the core algorithm called "SPEEDY," was developed. This is a train performance calculation system which is widely used in Japanese railway companies. The algorithm applies to the backtracking technique, which is known as a powerful method to solve complicated problems. Heavy dependence on the technique, however, had caused problems in displaying proper error messages, difficulty of program maintenance and other defects. This paper introduces a new algorithm of train performance calculation without using backtracking as far as possible. We have built the new algorithm in "SPEEDY" and confirmed that train running time calculated by the new algorithm is the same as that by the conventional algorithm.

Copyright (c) 2002 Railway Technical Research Institute