STO
Semi Automatic Train Operation
A level of train automation where normal train-driving functions are automated, while a driver remains onboard to supervise operation and perform specified operational functions.
Detailed explanation
Semi-Automatic Train Operation (STO) generally corresponds to Grade of Automation 2 (GoA2).
Under STO, normal train-driving functions such as acceleration, speed regulation, braking and accurate station stopping are performed automatically by the Automatic Train Operation (ATO) system. Automatic Train Protection (ATP) supervises train movement and ensures that the train remains within permitted safety limits.
A driver remains in the cab and continues to perform specified operational responsibilities. Depending on the railway system, these may include initiating train departure, controlling or supervising passenger doors, monitoring the platform-train interface, responding to emergencies and operating the train manually during degraded conditions.
STO is widely used on metro and urban railway systems because it provides many benefits of automatic train operation while retaining a driver for operational supervision and intervention.
Within the Grade of Automation classification, STO sits between GoA1 manual operation and GoA3 Driverless Train Operation (DTO).
Railway applications
mainline, high_speed, metro, light_rail, freight, depot
Standards and references
IEC 62290 series; IEC 62267