locking room

plural locking rooms

1. rail transportA room in a signal box, usually at ground level beneath the operating room, containing the interlocking mechanism for signals and points (track switches) below the lever frame in the operating room.

   The [Arboath North Signal Box] locking room's collection of chains, pulleys and wires resembles the inside of a piano, stretching to the 72-levered frame above. Lovers of steampunk will find it especially pleasing.

   2021 November 3, Dr Joseph Brennan, “Boxes with functions across the centuries”, in RAIL, number 943, page 57

   1 more example

   Within these boxes, interlocking between points and signals was the most crucial safety aspect, with the signalman's pulling of levers further safeguarded through the equipment in the locking room (often beneath the signalman's station), which prevented conflicting movements.

   2021 October 20, Dr Joseph Brennan, “A key part of our diverse railway heritage”, in RAIL, number 942, page 53