Signal Timing and Coordination—An Art of Engineering

Abstract

The scientific and engineering aspect of signal timing and coordination is reflected by sophisticated optimization algorithms, computer software, and roadway infrastructure to support servicing traffic flows. On the other hand, implementing a coordinated signal timing plan in the field often involves fine tuning of a plan in order to achieve the best performance. Such a field implementation and fine tune task provides a stage for the traffic engineers to demonstrate their intellectual and artistic skills of manipulating signal timing using the advanced traffic signal controller features. Therefore, traffic engineers often describe signal timing as a form of engineering art. This paper addresses such an artistic aspect of signal timing by illustrating various signal timing tricks applied on different cases. Specifically, the cases to be discussed include: left-turn phasing sequence, pedestrian handling, dealing with long arterials, and strategies for controlling closely-spaced signals. Applying the tricks and tips illustrated in this paper can provide quick fixes to some common operational problems without the need of significant capital investment. Finally, the paper also touches some basic issues related to traffic flow and roadway characteristics in China, and how the signal timing principles may be adapted to China’s urban arterials.