Traffic signal programming is generally divided into two problems. Firstly, the choice and sequencing of signal stages to be used and secondly, optimizing the relative lengths of these stages. The second problem is mainly numerical and has been solved using normal program techniques, but the first is still mainly tackled by trained signal experts using ad-hoc methods and rules of thumb. Since these skills are in short supply it was felt that an expert system could play a very useful role. The paper discusses the difficulties encountered, particularly in attracting interest among traffic experts and the problem of rendering the information into computer usable rules. The prototype is outlined and search techniques developed covered in detail.
Abstract