Between 5.15 pm and 5.45 pm, train managers, commonly known as guards, staged a ‘work-to-rule’ strike at Chhatrapati Shivaji Maharaj Terminus. Three pairs of suburban services between CSMT and Kalyan were cancelled. Several others were delayed. Platforms got crowded during rush hour. Normal services resumed after railway authorities sat down with guard representatives. The trigger was a single circular issued eight days ago. On May 7, Central Railway’s Principal Chief Operations Manager issued Correction Slip 15, introducing revised rules for how guards and motormen communicate while a train is moving. Under the new protocol, as a train approaches the next station, the guard must send an advance bell signal to the motorman, giving him time to anticipate the stop and begin braking. If the motorman doesn’t respond and the train comes in too fast, the guard must apply the brakes himself. The reasoning is straightforward. In April, a Badlapur-bound fast local overshot the platform at Vikhroli.…