At a designated station before a junction, the train stops and some of the cars are detached, with passengers or goods still on board.
For example: Dividing trains can sometimes cause issues for unwary travellers, who may board the wrong car and thus arrive at an unexpected destination.
The practice of portion working has been followed for a long time on the third rail network of lines in the South East of England, and has been more widely practised in continental Europe.
[2] Elsewhere in the United Kingdom, the practice has been less common, because of a general reluctance to design the necessary modern signalling systems, and because of legal constraints on competition between operators.
To ensure consistent journey times, the front part of a dividing train usually becomes the rear of the returning service when it reunites.