Up until a few years ago, the focus on connected vehicles (CV) was vehicle-to-vehicle (V2V) communications. This focus was important as critical safety of life applications were implemented. V2V applications and the standards they are built on are mature and ready for mainstreaming. With this in mind, the focus for CV began to turn toward vehicle-to-infrastructure (V2I) applications. Well before the shifting focus, there were many V2I applications identified and conceptually laid out, but not yet implemented. As V2I moved to the forefront, some applications were implemented, but many were left in the conceptual stages. Even those V2I applications that were implemented lacked the necessary insight from a road operator perspective. Road operators are those agencies, such as state departments of transportation, expressway authorities, and city and county agencies, responsible for operating and maintaining the roadway network.
The Tampa Hillsborough Expressway Authority (THEA) is one of three CV pilot sites selected by the U.S. DOT to deploy CV technology. THEA’s focus is on V2I applications that involve 1,600 private participant vehicles, 44 roadside units (RSU), and 500 private pedestrian smartphones. THEA’s V2I application implementation is forward-thinking to include communication between pedestrian smartphones and vehicle onboard units (OBUs), pedestrian smartphones and RSUs/signal controllers, and RSUs to OBUs. Two V2I applications of particular significance are the End or Ramp Deceleration Warning (ERDW) and Wrong Way Entry (WWE). ERDW receives information about the length of queues building at an intersection where an exit ramp terminates. Based on the length of the queue, ERDW calculates a safe advisory speed, which is broadcast to approaching vehicle OBUs to alert the driver. The WWE application determines when a vehicle is entering a ramp headed in the wrong direction using MAP and Signal Phase and Timing (SPaT). The driver is warned that they are headed in the wrong direction. If the driver continues in the wrong direction, the RSU is notified using traditional intelligent transportation system (ITS) detection equipment of the wrong-way vehicle. The RSU broadcasts a Traveler Information Message (TIM) to approaching vehicles (going in the right direction) of the approaching wrong-way vehicle.
One of the challenges in rolling out V2I applications is the lack of deployed CV technology. To overcome this challenge, CV applications must utilize both CV devices and traditional ITS devices. As CV-deployed devices become ubiquitous, the need to use traditional ITS devices will decrease and eventually they will not be needed, but for now integration is key to success.
V2I applications provide a rich data set that can be used to paint a picture of the traffic conditions on any roadway network. As V2I applications were conceived, there was no direct collaboration with road operators. Thus, the application’s functionality and data requirements may not be ideal for use in their environment. As a result, while THEA is utilizing some existing V2I applications, e.g., Pedestrian Mobility (PED-SIG) and Pedestrian in a Signalized Crosswalk (PED-X), the agency has modified the applications in order to meet its needs and requirements, as well as created new V2I applications such as ERDW and WWE.
THEA’s approach was to analyze the roadway network to identify real-world issues. These issues were used to build the basis for user needs and requirements. As part of developing these V2I applications, THEA analyzed what data they needed to collect to better operate their roadway network. THEA analysis included traffic management, incidents, tolling, enforcement and roadway maintenance. THEA is collecting all data generated by the vehicles and roadside units, and will evaluate the data to determine what data is useful in THEA’s managing its roadway network, including data to measure the effectiveness of the applications. V2I is here. The best way forward is, of course, forward.