Relay based interlocking for railway operation

In railway signaling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings.

Transport Administration Model 65 is a relay based interlocking system to control and monitor the signal objects (light signals and switches) at an operating location. There are two basic types of switchgear used, relay and computer-based interlocking. This recording was made at the switchgear operating location Norrköping and it will disappear when the new railway, the East Link, is built.

The microphone was located in the middle of the facility and relatively close to a number of "relay kits". Each object in the yard have a dedicated relay set for its function.
To enable the recording the cooling system was closed temporarily.

You can faintly hear the trains pass outside the building, especially a train five minutes into the recording.

Sound recordist: Torsten Nilsson
Photographer: Torsten Nilsson