Hardware in the Loop Traffic Simulation (HILS)
Contracting Agency: FDOT
Principal Investigator: Prof. Kenneth G. Courage
Traffic simulation has become an increasingly practical approach to estimation of performance measures for all types of highway facilities. Simulation is used to some extent in most districts to address unusual traffic control problems that are not amenable to more simplistic analytical treatments. The principal limitation of simulation models has, up to this point, been the rigid emulation of basic traffic control equipment and mechanisms, accomplished by internal routines within the simulation model itself. This limitation has placed severe constraints on the utility of traffic simulation as a problem solving approach.
Recently a new class of devices has been developed to allow actual traffic control equipment to replace the controller emulation built into a traffic simulation model. The “Controller Interface Device” (CID) opens new horizons for the use of traffic simulation as a problem-solving tool.
Figure1 HILS system
A simplified overview of the hardware in the loop concept is shown here. The simulation model, running in real time, communicates with the Controller Interface Device (CID) using an industry standard interface. For each second of operation, the simulation model tells the CID what detectors are occupied and asks for the state of each signal phase (red, yellow or green). The CID is connected to a standard traffic-actuated signal controller by the same cables that would normally connect the controller to the detectors and signal displays in the field. The CID passes the detector status from the simulation software to the controller hardware. It also passes the signal display status from the controller hardware to the simulation software. By this method, the CID is able to connect the abstract process of simulation to the real-world process of traffic control.
Recognizing the potential of this breakthrough in technology, the Florida Department of Transportation (FDOT) has initiated a project to identify and explore potential areas of application that could support the FDOT mission. The University of Florida Transportation Research Center performed this work. The specific objectives were to facilitate the implementation of hardware in the loop simulation in Florida, and to develop guidelines for future deployment by FDOT.
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Six CID units have been purchased and tested to be available to other agencies. Tests have been conducted with NEMA TS-1 and Type 170 Controllers.
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A series of workshops has been conducted regionally throughout the state (Ft Lauderdale, Tampa, Gainesville and Jacksonville).
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Two software tools have been developed to support the workshop presentations and the assimilation of the CID technology by personnel throughout the state.