A modification of the computer program TRANSYT-7F has been developed to reduce computational time and improve the performance index by using the conjugate directions search method in three dimensions. The original TRANSYT-7F uses the hill-climbing method to perform a two-step optimisation. This type of optimising procedure has been used in the TRANSYT program for many years, and even TRANSYT-7F's new version, 6.0, still applies the same algorithm. In this paper, a new search method is developed to obtain simultaneously the final cycle length, split, and offset. It is a one-step optimisation algorithm. From tests of 21 cases on a PC/AT, this modified TRANSYT-7F reduces computational time significantly and improves the performance index slightly compared with the new TRANSYT-7F. It also allows the user to consider the spillover effect, perform arterial priority or link maximum-allowed delay, and fix the offsets for designated intersections. Currently, this program can be used not only as a detailed offline signal-timing analysis tool but also as a part of computing software for four newly developed traffic control systems in Taiwan to generate online signal-timing plans.
Samenvatting