Thank you to Peter for writing in and sharing news about his Android app called V2X2MAP, which makes Vehicle-to-Everything (V2X) radio traffic visible on a live map via an attached ESP32 board. The app is not free but costs only a small US$2.49 fee.

V2X is a cooperative wireless system in which vehicles and roadside infrastructure continuously broadcast small messages in the 5.9 GHz band. Equipped cars broadcast their position, speed, heading, and brake status about 10 times per second, while traffic signals broadcast their phase and timing, lane geometry, and event-driven hazard warnings. It can be thought of as something like ADS-B or AIS for cars, though at a much shorter range (typically a couple of hundred meters), with the added feature that roadside infrastructure also transmits.

V2X is designed to enhance vehicle safety, allowing vehicles to know about obstacles, traffic phases, and road geometry in advance. Currently, two incompatible standards are used: the older DSRC (Wi-Fi-based) and the newer C-V2X (cellular-based). Most markets are moving towards C-V2X because it provides short and long-range communications.

The V2X2MAP Android app works together with a $20 Waveshare ESP32-C5 board, which has an onboard 5.9 GHz WiFi 6 radio. The ESP32 receives the older Wi-Fi DSRC signals, particularly the ITS-G5 standard, which appears to be used only in Europe. Once running, V2X2MAP and the ESP32 decode the surrounding V2X broadcasts and plot live vehicles, hazard warnings, and traffic-light countdowns on a map of your immediate area.