After the doors are opened, the conductor sticks their head out the window to observe passenger boarding and exiting. The doors stay open for at least ten seconds, and when the conductor decides to close the doors, the conductor announces a door-closing warning using a PA system on the train. When the platform is clear, the conductor closes the doors in the rear cars. When a locked-door signal is received, the conductor closes the doors in the forward section of the train. Door chimes warn passengers that the doors are closing. When all the doors are closed, the conductor removes the door key, which alerts the motorman that it is safe to proceed.