Hardware-In-The-Loop On-ramp Simulation Tool to Debug and Test the Universal Ramp Metering Software

An on-ramp simulation system that can be used to debug and test the Universal Ramp Metering Software (URMS) is presented. The tool includes a simple car following microscopic traffic model for the on-ramp and a Controller Interface Device (CID), which interfaces a standard personal computer with a 2070 traffic controller. The CID consists of the low cost and commonly available National Instruments (NI) USB-6501 24-Channel Digital I/O device and a basic circuit that interfaces the 5-Volt TTL logic from the Digital I/O board to the 2070 controller. The resulting hardware-in-the-loop simulation tool systematically reads the phase states from the controller and changes detector states based on the cars trajectories as displayed on the on-ramp simulator. With this tool it is possible to check the performance of the 2070 controller running the URMS as if the traffic controller was operating on a standard on-ramp managed by Caltrans. Finally, the real-time nature of this tool is discussed based on a quantitative analysis of the simulator performance running on the Windows XP operating system.