Aug 2015

Signals I: Development, Regulation and Use

For more than 150 years, signals beside the tracks have been used to provide guidance to the operators of trains. Originally this was a simple “stop” or “go” message, but over time it became more elaborate, and the signals themselves more complex. Today signals provide fairly detailed guidance that allows for efficient and safe operation. But how they do that varies a lot between railroads. Signals have also become specialized, with signals at stations, junctions and similar points (“interlocking signals”) behaving somewhat differently from signals along uninterrupted lengths of track that exist mainly to separate trains (“block signals”). There are also many other, more specialized, signals.

Signals used in Japan are both simpler than those used in many other places, and allow for some capabilities that others do not (or that they do using more complex methods). But they also have a lot in common with signals used elsewhere. That shouldn’t be a surprise, as Japanese practice originated, as did that of many other countries, in British practice of the late nineteenth and early twentieth centuries. However they were also influenced by North American practice (which itself originated from mid-to-late-nineteenth century British practice). And they created some things unique to themselves. But I think that to understand them, it helps to take a look at how signals are used on railways around the globe, particularly block signals, as Japan has streamlined their system by focusing on block functions.

I’m going to leave Japan for this post and wander the globe for a bit before I get back to explaining Japanese signals in a separate post. But I will include Japan in today’s discussion.