Quote:
Originally Posted by bramleyman
NO chance of this happening at Downham Market, where there is 1 signalman/woman, who lowers the barriers at LEAST 5-10 minutes before ANY train is due to pass through, causing Serious tailbacks into town and to the roundabout west of the station.
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Which as I'm sure you know is because of interlocking on the
Locally Operated crossing. Although the Fen Line is Track Circuit Block signalled nowadays, most of the multiple aspect colour light signals are still situated in their old Absolute Block signalling positions. So before the Downham Market signaller can clear (what is in effect) the Down Home Signal into the station, he/she must have already lowered and locked the crossing gates. Since the train on the Down Line coming towards Downham from Littleport is approaching at between 90mph and 75 mph, the home signal needs to be cleared several minutes earlier otherwise the train will be 'checked down' by preceding signals showing the caution sequence.
Contrast this with the nearby
Automatic Half Barrier crossing at Downham bypass, where the gates are only down ~7 secs before the train passes ! This is because it is operated via treadles which the train 'strikes'. The signalling is not interlocked with this AHB crossing (although they're often set up so that a gate failure sends the signal in the rear to danger).
Hope this makes sense, BW