Use on-board connected vehicle (CV) technology and SPaT / MAP infrastructure messages to prevent wrong way entries on reversible express lanes.
Success Stories from the USDOT’s Connected Vehicle Pilot Program
Made Public Date


United States

Connected Vehicle Pilot Deployment Program: Success Stories


In September of 2015, USDOT selected New York City Department of Transportation (NYCDOT), Wyoming Department of Transportation (WYDOT) and Tampa Hillsborough Expressway Authority (THEA) as the recipients of a combined $42 million in federal funding to pilot next-generation infrastructure and vehicle technology under the Connected Vehicle Pilot Deployment Program.

Lessons Learned

All of the connected vehicle applications being implemented and evaluated in the Connected Vehicle Pilot Deployment Program did not need to be developed from scratch. Software developers for the three CV Pilot sites have been able to take advantage of software prototyped by many programs, including the USDOT’s Dynamic Mobility Applications (DMA) program and the Safety Pilot Model Demonstration project in Ann Arbor, MI.

One of THEA’s six use cases is to prevent the entry of vehicles going the wrong way (against the permitted flow of traffic for Traffic Signal the given time of day) onto the Reversible Express Lanes (REL) of the Lee Roy Selmon Expressway. Entry into the REL is governed by a traffic signal so THEA started by using existing Red Light Violation Warning (RLVW) software. The plan was to treat the traffic signal as if it changed only twice per day (i.e., at the times the directionality of the REL was reversed) and that a vehicle trying to enter the REL the wrong way could be detected as if it were trying to run a red light.

However, the complexity of the intersection (cars could enter the REL from three intersection approach directions, and could go in legal directions as well as the illegal direction) made this approach unworkable. THEA evolved the RLVW application into a Wrong Way Entry (WWE) application. The key change was to adapt the Signal Phase and Timing (SPaT) and MAP (intersection geometry) messages broadcast by the traffic signal to include a bit for each approach lane indicating whether the direction for that lane is "revocable", i.e. changeable. By examining the "revocable" bit for the lane of an approaching vehicle and the time of day, the vehicle’s Onboard Unit (OBU) can determine whether it is going the wrong way. If so, it will send a warning message to the vehicle’s driver and broadcast a warning message to the drivers of approaching vehicles.

Goal Areas