When is single-track operation generally necessary?

Single-track operation is generally necessary when signal cables are being replaced in an under-river tunnel. This situation typically involves a need to restrict train movements on one track to ensure the safety of workers and equipment during maintenance activities. By converting to single-track operation, the railway can facilitate the timely completion of essential infrastructure work while minimizing disruptions to service.

In scenarios like maintenance checks on the tracks or during weather emergencies, a complete or partial service interruption may occur, but these do not automatically necessitate a single-track operation. Similarly, during rush hour, the demand is typically for increased capacity and the operation needs to be optimized for dual-track use to accommodate the higher volume of trains. Thus, the context of maintenance work where critical components like signal cables are involved makes single-track operation essential to ensure safety and operational integrity.