INVESTIGATION INTO THE EFFECTS OF SPECIAL TRAFFIC SIGNAL PROGRAMS AS AN ALTERNATIVE TO THE TEMPORARY DISCONNECTION OF TRAFFIC SIGNALS AT OFF-PEAK PERIODS

The reseach objective is to investigate the off-peak traffic volume effects of the following traffic signal control systems under a variety of traffic conditions, and to make safety-conscious comparisons with the effects of traffic signal disconnection: 1) traffic-non-dependent-control: normal fixed-time program or modified fixed-time program with reduced cycle time; and, 2) traffic-dedpendent control: request for green from the approach road direction or all systems red. The effects of the individual systems are analyzed by means of stochastic computer simulation using parameters such as 'number of stops', 'waiting time' and 'journey speed'. The analysis produces the following recommendations: in most cases, traffic signal disconnection results in smoother traffic flow than traffic signal control. However, for reasons of safety, traffic signal disconnection should be discouraged. Irrespective of traffic volume, request for green from the approach road direction is particularly effective where there is a marked difference in the levels of traffic volume in the main and approach road directions. Where there is only a slight difference in traffic volume levels, 'all systems red' is effective up to a traffic volume at junctions of some 700 vehicles/h. However, for greater levels of traffic volume, the traditional system of fixed-time control with as small a cycle time as possible is to be recommended.