IMPROVED NETWORK CONTROL BY USING TRANSYT

A description is given of TRANSYT-a traffic network study tool which combines a set of simulation, optimisation and output programs. The work described in the article was intended to improve both the reliability and speed of convergence of the optimisation facility to minimise the performance index for a network. A number of optimisation methods are discussed, and the results presented of three of them being implemented in transyt. These methods were (a) the simplex method for non-linear systems, (b) pattern search and (c) rectangular search. Neither method (a) nor (b) solved the problem. The linear transformation of the variables is a major contribution to the successful performance of any optimisation method, and therefore to the rectangular search method which has become the best optimisation method for the non-linear optimisation problem of transyt. (TRRL)