In urban rail transit, due to the n

In urban rail transit, due to the normal driving mode adopted by the ATP system, it is the only driving mode that can continuously control the train operation and ensure the safe operation of the train for a long time. Degraded driving mode is a driving mode adopted by the ATP system to reduce the risk of manually operated trains under speed limit conditions. However, blasphemy does not avoid all risks, especially it does not protect the train from turning off the signal, so the normal driving mode must be very stable and reliable to minimize the use of degraded driving mode. In view of the above factors, it is proposed that the reliability of normal driving mode of ATP system should be higher than 99.99% in foreign urban rail transit projects. Where, month is the system reliability probability; T is the design life of the system; MTBF is the average time of grateless toast.