ADS-B is also fitted to some airport service vehicles.
ADS-B (Automatic Dependent Surveillance-Broadcast) is a foundational NextGen technology that uses the GPS satellite system to track aircraft in real time. That same satellite precision has now been adapted to airport vehicles, making runways safer and more efficient.
When airport vehicles are equipped with ADS-B, they can be tracked in real time along with aircraft at the airport. Displays give pilots, controllers, vehicle operators, and airport and airline managers a better view of airfield operations. This capability has many uses and can be especially helpful at night or during low-visibility weather.
List of airport ground vehicle transmitter maps.
https://www.faa.gov/nextgen/programs/adsb/vehicle_transmitter_maps/