Quote:
Originally Posted by hereward
BW have all the semaphore signals gone now?
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Well semaphore signals belong to the era of Absolute Block - which is a time when there were signal boxes everywhere. Sometimes there were 3 or even 5 boxes at one station alone, if the traffic was intense.
Because of the mechanical force required to move the cables or links, there is a limit to how far away a signal can be. Distant signals were the worst of course. One reason for the lack of women in the job originally is that in some boxes you had to be very strong just to pull off. I'm told that a lot of it was technique, but they're still damn heavy.
Network Rail has for some time persued a policy of shutting boxes and installing colour light signals, which can be controlled from a far away 'hardened bunker (which they call a Signalling Centre).
But there are still some boxes remaining on quieter lines, waiting for the day that in-cab signalling makes physical signals unnecessary. Downham Market near me is a typical hybrid. It has Colour Light Signals for the running lines, but has kept a few semaphore shunt signals that are only used occasionally. It's not ecomically viable to convert them to LED Ground Position Light signals.
All my career I've been lucky enough to work exclusively on Track Circuit Block signalling, but I'm told that about 40% of the network is still Absolute Block, and many of these have retained their semaphores.
Hope this makes sense, BW