It is compatible with the original signal system, which has a high failure rate with a new CBTC signal system, quickly reduces the operation failure rate of transformed lines, upgrades the CBTC system and ensures the new system stability. During the transformation of onboard equipment, the ground and trackside equipment are basically unchanged. Still, the transformed onboard signal cabinet can be fully compatible with existing equipment and has the capability for upgrading the ground system into CBTC system by phases without the need of secondary transformation of the vehicle.