Relaisstellwerken
Relaisstellwerken, or relay interlockings, are a form of railway signaling installation in which electromechanical relays implement the interlocking logic that controls signals and point machines. They were widely used on German-speaking railways from the late 19th century through the mid- to late 20th century, forming the backbone of many mainline signaling systems before electronic interlockings became common.
A Relaisstellwerk typically comprises a control panel used by the signaller, a cabinet housing the relay logic,
Safety and reliability are achieved through the failsafe nature of relay logic: loss of power or a
With advances in electronics, many Relaisstellwerken were gradually replaced by electronic or computer-based interlockings (ESTW) and