Even where it is not authorised, a shunting movement can be allowed to enter a portion of line that is already occupied providing that it is for the purpose of:
- attaching vehicles
- detaching vehicles
- removing vehicles.
Driving towards another train
When it is permitted to drive a train towards the rear of another train, such as where trains queue to enter or exit a depot, the driver must:
- proceed with caution
- not pass a signal which has been cleared for the train in front until it has been replaced to danger and then cleared for his movement.
- UK Rulebook - Permissive Working. GE/RT8000 Rule Book Module TW1 (Train Working) Section 20 (PDF).