Development of an Application Programming Interface (API) in Simulation to Evaluate Real-Time Signal Control

Application Programming Interface (API) is a feature available in some traffic simulation programs to allow users to customize changes in simulation such as driver behavior, ramp metering control strategies, and other ITS applications. This paper presents a method to develop an API in AIMSUN, a stochastic and microscopic simulation model, to evaluate a previously developed adaptive signal control algorithm, i.e., DP algorithm. The algorithm is coded in C++ by combing the functions and five routines available from the GETRAM extension module embedded in AIMSUN. The developed API allows dynamic link between the DP algorithm and the simulation environment. During simulation run time, the real-time traffic measurements provided by detectors in the network feed the DP algorithm that, after processing, makes the decision of signal controls. These decisions are then transferred back to the simulated network, which emulates their operations through the signal controllers. This research has demonstrated the API function is a useful tool to assess external ITS applications when these innovative ides are not supported by the simulation program.