Vehicle transponder tags (devices that are uniquely encoded with an identification number, often with millions of possible numbers) can be issued to suitably authorised personnel. These personnel can then be individually identified by a semi-automated or fully automated system.

Personnel without a vehicle transponder tag, or those with one but with an identification number not accepted by the system, can be restricted from certain areas, or restricted from part or all of the system.

Tags can be fitted to many type of vehicles, including rail wagons and locomotives. Radio frequency read ranges vary from 1m to 5m. The vehicle must pass a transceiver device in order for the tag to be read.