by StevieG » Mon Mar 19, 2018 11:54 am
There used to be (still are?) Rule/Instructions for slight or moderate winter weather on periodically working points that had not been used frequently to attempt to keep everything going (e.g., pre-1972, the 1950 Rule 61 included "Points not frequently used must be occasionally worked by the Signalman to assure himself that they are in order.", though that was not specifically weather-related.)
But if the weather got too bad, any established more restricting policy could be pronounced as to be applied (usually by the Control office AFAIR.)
Thirty years ago I was tasked with reviewing the Kings Cross Area (KX -Stoke)'s "Key Route Strategy" for the more severe times which dealt precisely with identifying points which were essential to be kept workable, where possible also selecting those which were in fairly compact areas to optimise where ground staff could more easily attend when necessary, often purposely listing those which were not to be worked in more isolated locations that would otherwise have been more desirable speedwise or permitted parallel movements but where staff resources were less likely to get to promptly in the case of problems or were perhaps inaccessible in prevailing conditions. It should be noted that this was an entirely power-signalled area by that time, as has Worting Junction been for very many years.
Over many decades now there have of course been several types of point heater used to try to prevent point switches freezing and/or becoming blocked by snow or ice (including lumps of same which can drop from passing trains).
One other problem which became more apparent with the advent of authorised train speeds exceeding 100mph when lying snow was of a drier powdery nature was points becoming blocked by the huge clouds of snow drawn into the air in the slipstream of high speed trains.
Most obvious when operating were those heaters which used bottled gas fuel and were turned on manually by the PWay staff or (not always successfully) automatically by temperature sensing equipment. These could then be heard 'popping' away, and in darkness emitted a row of visible blue-ish low flames along the outside of the stock rails.
I believe electric types have been more effective in more recent times but have no idea of their means of operation or effectiveness, and in any case even the best could probably be overwhelmed by sufficiently heavy falling or drifting of snow.
One other factor which has occurred to me regarding points with high diverging permissible speed, but about which I have no knowledge, is that the point switches are inevitably long (picture those few places such as Colton and Rugby T.V. Junctions, where [using 'H' length switches?] the two divergent permissible speeds are both 125mph), so the movable lengths of the switches, and the number of movement drive points which they have, are much greater, and so they may be more difficult to effectively heat.
And in any case if a set of points cannot fully move to, and be detected in, their opposite position in bad weather, it is quite possible, even after several attempts, that snow or ice could also prevent them being successfully restored to their previous position, potentially creating the situation of their then being unusable in either position, and the signaller is then 'snookered', unable to move anything over them pending site attention to either get detection restored or even get them working again. It's also possible to be left with the least desirable circumstance for train movements, of only being able to get site assurance that the points have been secured but signal/s still cannot be cleared through inability to restore detection, necessitating each driver being verbally authorised to pass the signal/s at Danger.
Last edited by
StevieG on Mon Mar 19, 2018 1:05 pm, edited 1 time in total.
BZOH
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