Visual Education Tools to Illustrate Coordinated System Operation

Abstract

The configuration of a single controller in a coordinated arterial signal system requires the programming of approximately 250 parameters ranging from minimum green times to complex hardware-specific settings that determine how unused green time is allocated to competing phases. When this parameter count is extrapolated to a 10-intersection arterial (2,500 parameters), one or more data entry errors are likely to occur and must be identified and corrected. Ensuring that the resulting coordinated signal system operates as designed requires an exceptionally high level of expertise to confirm by visual field observations and a perhaps unattainable level of expertise in verification by inspection of data entry screens in an office. There is a clear need for visualization tools to provide educational insight into how coordinated signal systems should be expected to operate under different parameter settings and to document coordinated system behavior. In this paper a series of graphics was developed to visualize coordinated system operation characteristics such as time-of-day schedule change time, observed cycle length, green time and split time, coordinated phase actuation, early return to green, arrivals over advance detection relative to green indication, progression quality characteristics related to offset, adjacent signal synchronization, coordinated phase operation in rest, plan time changes, preemption, impact of queuing, and longitudinal analysis of splits. These graphics can be used as a new learning tool, as well as a visual feedback tool to confirm that a coordinated system is operating as expected.