Where does interlocking collide?

In railway signalling, an interlocking is the arrangement, mechanical, relay, or computer-based, that constrains signals and points so that only mutually safe combinations can ever be set, making it impossible to clear a signal for a route that conflicts with another. Theeg and Vlasenko's Railway signalling & interlocking compendium sets out the logic by which routes are locked, proved, and released so conflicting movements are physically prevented. The referent is a safety logic system that binds the state of track devices together, assessed by whether unsafe combinations are excluded, and it shares only the word with the pattern of shared company directors.[1]

Unit

The set of signal and point states the logic permits or forbids

Recovery means

Not applicable

Measured by

Verified by route-locking and conflict tables showing that no unsafe combination of signal and point settings can be commanded

In organizational sociology, an interlock exists when a person sits on the boards of two companies, so that a web of interlocking directorates ties firms together and can carry information, influence, or coordination between them. Mizruchi's 1996 What do interlocks do? reviews what such board ties actually accomplish, distinguishing interlocks that reflect collusion or control from those that serve as channels for monitoring and the diffusion of practices. The referent is a network tie between organizations created by shared directors, measured on the graph of boards and people, and it has nothing to do with railway safety logic beyond the image of parts locked together.[2]

Unit

The presence and pattern of shared directors linking firms

Recovery means

Not applicable

Measured by

Measured on the board-interlock network by tie counts, centrality, and the correlation of interlocks with firm behaviour