A portable computer system and method of operating a vehicle using the portable computer system in a communication-based train control (CBTC) system territory is provided. The portable computer system includes a sensor and a transceiver that is communicatively coupled to the sensor and to the CBTC system, wherein the portable computer system configured to be removably coupled to the vehicle. The method includes verifying that the vehicle is operating with one of a non-operational CBTC computer system and a non-CBTC computer system, and removably coupling a portable computer system including at least one sensor and a transceiver that is communicatively coupled to the sensor to the vehicle such that the transceiver is coupled in communication with the CBTC system.