Tricks and Tips about Signal Timing and Coordination

Signal timing and coordination involves sophisticated optimization models, algorithms, and the roadway infrastructure to support the operations of traffic signals. On the other hand, an optimized signal timing plan also needs fine tuning in the field in order to achieve the best system performance. Such a field implementation and fine tune task may involve dealing with many factors, such as local driving habits, that cannot be anticipated and addressed using scientific approaches. Therefore, traffic engineers often describe signal timing as a form of engineering art. An experienced signal engineer often applies many innovative techniques combining the knowledge and skills from both engineering principles and artistic minds, namely the tricks and tips. This paper illustrates various tricks and tips used by practical signal engineers using several case studies. Specifically, the cases to be demonstrated 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 investments.