Abstract: Disclosed is a fail-safe system for vehicle proximity including, in some embodiments, an autonomous-vehicle control system onboard a vehicle, a brake system of the vehicle, and at least one onboard transceiver onboard the vehicle. An autonomous-vehicle control-system module can be configured with collision-determining logic. A brake-system module can be configured to slow down or stop the vehicle upon receiving a braking-process instruction from the control-system module. A transceiver module can be configured to receive signals from at least one external transmitter moving toward or away from the vehicle. The transceiver module can be configured to send to the control-system module proximity information for the external transmitter as it moves toward or away from the vehicle.