Controller Interface Device Software Documentation

For years, traffic engineers have used traffic simulation software to develop, model, and test signal timing plans. However, before timing plans can be implemented in the field, they must be fine-tuned in an actual traffic controller operating under actual intersection conditions. Testing a signal timing plan in the field can cause minor or even major traffic disruption, creating delay and frustration for motorists and pedestrians alike. Real-time hardware-in-the-loop traffic simulation (HILS) can test timing plans in the office or lab rather than out in the field. The Controller Interface Device (CID) is the key component of the real-time simulation system. This paper provides an overview of real-time hardware-in-the-loop simulation and then discusses CID hardware design. Finally, HILS interface software design for three different simulation models (CORISM, VISIM, SimTraffic) will be explained. Introduction Transportation engineers often use computer models to evaluate or test how well a traffic facility will operate under a given traffic demand. Depending on the complexity of the system under study, the engineer may use either a macroscopic deterministic model to evaluate the performance of a fixed-time signalized intersection or a stochastic microscopic simulation model (CORSIM [1], VISSIM [2], or SimTraffic [3]) to test the operation of actuated signalized intersections during over-saturated conditions. But one of the most serious limitations of these simulation models is that their signal controller emulator sub-models do not include many of the features present in today‘s traffic controller. The continuing changes to control algorithms as well as the need for manufacturers to maintain propriety precludes simulation software model developers from including these features into their models. For example, the FHWA TSIS/CORSIM model [1] uses actuated traffic control technology from the 1980‘s and does not allow the user to specify the advanced control algorithms that have been developed in recent years. HILS [4] and the controller interface device that makes HILS possible were introduced to the traffic industry during the last 7 years. With HILS, engineers can test a signal-timing plan using