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Railway geology!

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AndrewE

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I came across this webpage earlier on:
http://www.southampton.ac.uk/~imw/Ridgeway-Railway-Cutting.htm
and in the 4th picture of Bincombe tunnel mouth it seems that there are extra timbers along the nearer track. (Other railway photos further down) Could this have been protection in case of another slip of clay from the cutting side? The timbers don't seem right for a third rail as they both seem to be on the nearer track. Any other ideas?
(Sorry, I can't get the picture to paste into this post.)
A
 
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Spartacus

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It looks a bit like an interlaced sand drag.

I was thinking the same, especially as it's only on the side of the line which would be usually used for trains running towards the tunnel.
 

30907

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And given the gradient back down towards Weymouth (1 in 50?) , plus the cutting side, catch points leading into a sand drag would (in theory) deal with any runaway with least risk of blocking the down line.
 

AndrewE

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Thanks all, I would have taken ages to puzzle it out (if ever)
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Of related interest, the geographer Michael Freeman has researched the importance of early railway excavations in the development of the science of Geology

See his book free online


From the Preface: "The task of railway excavation brought surveyors, engineers and navvies face to face with a perspective on earth history that was as raw as it was vast. As contractors' gangs cut their way through successive bands of rock to try to make for a level permanent way, they exposed not only sedimentary formations in all their rainbow-like hues, untouched by the ravages of wind and water, but fossil beds by the score."
 

furnessvale

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And given the gradient back down towards Weymouth (1 in 50?) , plus the cutting side, catch points leading into a sand drag would (in theory) deal with any runaway with least risk of blocking the down line.

Yes, I have seen them in various locations, Copy Pit seems to ring a bell.

The driver of a train running away would whistle up for the signalman to turn him into the sand drag to slow him down. The other end of the drag turns the train back onto the running lines.
 

Railsigns

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The driver of a train running away would whistle up for the signalman to turn him into the sand drag to slow him down. The other end of the drag turns the train back onto the running lines.

The usual arrangement is for the sand drag to be connected to the running line at only the far (uphill) end, by trailing points which are sprung to divert vehicles running back into the sand drag.
 

AndrewE

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Of related interest, the geographer Michael Freeman has researched the importance of early railway excavations in the development of the science of Geology

See his book free online


From the Preface: "The task of railway excavation brought surveyors, engineers and navvies face to face with a perspective on earth history that was as raw as it was vast. As contractors' gangs cut their way through successive bands of rock to try to make for a level permanent way, they exposed not only sedimentary formations in all their rainbow-like hues, untouched by the ravages of wind and water, but fossil beds by the score."
Thanks for that link...
I suppose we should also acknowledge the work done (also in the West Country) earlier by canal pioneers in this context - which the book starts with:
https://en.wikipedia.org/wiki/William_Smith_(geologist)
 
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furnessvale

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The usual arrangement is for the sand drag to be connected to the running line at only the far (uphill) end, by trailing points which are sprung to divert vehicles running back into the sand drag.

That is the case for a trailing sand drag, or conventional catch points, but the one being discussed here, and I believe others, like Copy Pit, is a facing sand drag which would only be brought into use at the (urgent) request of the driver.
 

Railsigns

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That is the case for a trailing sand drag, or conventional catch points, but the one being discussed here, and I believe others, like Copy Pit, is a facing sand drag which would only be brought into use at the (urgent) request of the driver.

From the photograph being discussed in this thread, it is impossible to tell whether the sand drag is connected by facing or trailing points, but my assumption would be trailing.

It seems incredible that a signalman should have the ability to suddenly throw a set of facing points in front of a train approaching at speed.

Here is the signal box diagram for Copy Pit:
http://www.lymmobservatory.net/railways/sbdiagrams/copy_pit_q45.jpg

The only facing points in the running lines are those leading to the loops.
 
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furnessvale

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From the photograph being discussed in this thread, it is impossible to tell whether the sand drag is connected by facing or trailing points, but my assumption would be trailing.

It seems incredible that a signalman should have the ability to suddenly throw a set of facing points in front of a train approaching at speed.

Here is the signal box diagram for Copy Pit:
http://www.lymmobservatory.net/railways/sbdiagrams/copy_pit_q45.jpg

The only facing points in the running lines are those leading to the loops.

I do not know how old your diagram of Copy Pit is. I note it is BR. I am only going on memory that there was such a sand drag there, perhaps I have the wrong location.

Going back to the photo being discussed. I now realise that the train is travelling downhill so it is perfectly feasible that these are standard trailing catch points with a sand drag extension.

Edit to add. Re your comment about turning points in front of a train at speed. It depends on what the alternatives were. If the alternative was to let the train go, gather up even more speed and have a major pile up in the next passenger station, it could be a reasonable alternative.

Secondly, speed is relative. A driver friend of mine once told me, if you came over the top of Brentwood bank with the unfitted Southminster sand train at more than 15mph, you weren't going to stop before the sidings at Mile End so you'd better pray for a clear road.

Further edited to add a link to an article which describes the use of interlaced facing sand drags, but I hasten to add that the Woodhead is not the area I am thinking of as I never worked on that line.

https://signalbox.org/branches/nfl/hadfield.htm
 
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furnessvale

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Given that a sand drag is intended to stop a train, how does a train restart in one to return to the main line or not actually stopped who decides it has slowed enough to negotiate the exit (without a speedo)?

I have no detailed knowledge but the item I linked clearly showed that they existed and were not a figment of my imagination.

Several possibilities spring to mind.

The driver would probably decide if it was safe by a whistle code to the signalman.

The sand was probably no higher than rail level providing retard without a full stop.

Any runaway would no doubt be unfitted with pinned down brakes. Releasing those brakes would drop weight onto the loco assisting a restart.

"Someone" would have to go in front and clear a flange groove in the sand!

As for speedos, we are talking a different railway with a totally different safety culture that I joined in 1964, let alone earlier days!
 

edwin_m

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I guess the resistance of the sand drag would be very speed dependent, so a train could be hauled out at low speed but one arriving faster would be slowed down.
 

D Foster

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Given that a sand drag is intended to stop a train, how does a train restart in one to return to the main line or not actually stopped who decides it has slowed enough to negotiate the exit (without a speedo)?

Answer to how does a train re-start... Carefully!!! :D
Apart from the fact that trains (and odd items of stock aren't actually supposed to end up in a drag - or in the dirt - if they do mess about there is likely to be a question of lining the wheels up with the rails. This can be done...
I have seen 3 axles of a Crompton in the dirt and restored to where it should be with the judicious application of fishplates - yes - this is possible... unfortunately they then put a couple of axles off at the other end :(
It is also possible to drag 24 grampus that had got bored with following the rails of a siding back on.
These operations are done very slowly!

Facing Traps are very rare outside of locations where movement will be slow. In all my experience it is necessary to close the trap (i.e. set the route into continuous track) before a movement can be signalled toward the trap. On anything but very slow lines it is quite usual for there to be either a very long over-run between the last signal before the trap or for both the last signal and the signal on the approach to it to have to be cleared - with the facing trap set back into the continuous line.
This means that - apart from anything else - signals would have to be returned to danger/stop before the points could be moved. There is a significant chance that some form of release (e.g. a 2 minute delay or a wind-out) would hold the road after a signal or signals were put back. There is also a serious chance that the tracks would be track circuited and the route held by occupation of the tracks.
The result is that it is very unlikely that traps would be swung to derail a movement except where the movement would always be slow.

Facing movement runaways - especially at speed - would be a significant problem to divert... For a (major) start - if the movement is travelling fast (and for - short wheelbase - unfitted sand wagons 15mph is not slow) there would be serious issues of the movement potentially derailing through the points - even with a relatively low angle of departure.

Once into a trap - and particularly into a sand drag - there would be a whole load of questions to be answered before attempting to re-rail the movement... It would not trundle happily on from a far end as if it had merely been in a loop.

As for "blowing" to be diverted into a trap... This would require close proximity to the controlling Signalbox... No signalman is going to want to take responsibility for derailing a fast moving train any more than a footplate crew is going to opt to be dumped in the dirt.
The last said - One of my Inspectors did see a light loco try to sneak out against the signal as soon as he had set the route from a siding - and put the trap back - landing the loco (slowly) in the dirt... It was generally reckoned that no-one made Inspector until they had achieved such a feat or similar.

:)
 

Joseph_Locke

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Once into a trap - and particularly into a sand drag - there would be a whole load of questions to be answered before attempting to re-rail the movement... It would not trundle happily on from a far end as if it had merely been in a loop.

My point in a nutshell - a double-ended sand drag is a bit of a nonsense:

furnessvale said:
The driver of a train running away would whistle up for the signalman to turn him into the sand drag to slow him down. The other end of the drag turns the train back onto the running lines.

The only circumstance in which a double-ended sand drag could justified is where a facing trap point leads to one and so does a trailing catch point. This would have to be the nadir of a pair of steep (and opposing) gradients. This probably explains why I've never come across one ...
 

furnessvale

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My point in a nutshell - a double-ended sand drag is a bit of a nonsense:



The only circumstance in which a double-ended sand drag could justified is where a facing trap point leads to one and so does a trailing catch point. This would have to be the nadir of a pair of steep (and opposing) gradients. This probably explains why I've never come across one ...

Maybe a bit of a nonsense, but a nonsense I have personally seen as endorsed by the article I quoted further back up the thread.

As I said earlier, we are talking a very different railway from today's ultra cautious version.
 

furnessvale

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The sand drag that used to be on the UP line approaching Goole Swing bridge was Facing.
https://www.flickr.com/photos/ingythewingy/6976200987/in/photostream/
As is the one at Goathland on the NYMR.
https://en.wikipedia.org/wiki/Catch_points#/media/File:Catch_trap_drag.jpg

Thanks for that, but in both cases these would probably be used as protection for the bridge or main line and switched out when the signal was cleared.

The issue being discussed is a sand drag which can be switched in front of a runaway train, and, in the case of the one on the Woodhead and at least one other I have seen, having got the runaway under control, the train is switched back to the running lines.
 

edwin_m

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As for "blowing" to be diverted into a trap... This would require close proximity to the controlling Signalbox... No signalman is going to want to take responsibility for derailing a fast moving train any more than a footplate crew is going to opt to be dumped in the dirt.

I suspect any whistle codes must actually have been used at the box before the one controlling the relevant junction, otherwise the route could not be set in time to give the train clear signals. Translating this to the case of a facing sand drag, a runaway train could have whistled for it at the previous box and the signalman there could have confirmed it was running too fast, crew in distress etc. They would then have communicated by phone or perhaps a bell code to the box that actually controlled entry to the sand drag. But this is just my surmise and I've no idea if it actually worked like that.

Another reason for the sand drag being double-ended might be if there was a risk of the train arriving fast enough to run right through. Rather than piling up in a heap if the sand drag rails simply ended, it would then emerge at reduced speed with the sand still retarding the rear part of the train. Particularly if the track was level by this point it would have a much better chance of stopping.
 

furnessvale

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I suspect any whistle codes must actually have been used at the box before the one controlling the relevant junction, otherwise the route could not be set in time to give the train clear signals. Translating this to the case of a facing sand drag, a runaway train could have whistled for it at the previous box and the signalman there could have confirmed it was running too fast, crew in distress etc. They would then have communicated by phone or perhaps a bell code to the box that actually controlled entry to the sand drag. But this is just my surmise and I've no idea if it actually worked like that.

Another reason for the sand drag being double-ended might be if there was a risk of the train arriving fast enough to run right through. Rather than piling up in a heap if the sand drag rails simply ended, it would then emerge at reduced speed with the sand still retarding the rear part of the train. Particularly if the track was level by this point it would have a much better chance of stopping.

There were, and perhaps still are, distinct whistle and bell codes for trains running away.

Edit to add:

A check on Google reveals the signalbox bell code for train running away in right direction is 4-5-5
 
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edwin_m

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There were, and perhaps still are, distinct whistle and bell codes for trains running away.

Edit to add:

A check on Google reveals the signalbox bell code for train running away in right direction is 4-5-5

Indeed. It's probably still in the rule book that repeated short blasts on the horn signifies a train in distress. But I wonder if something more than that was appropriate before deciding to divert a runaway train into the sand drag. There could have been a special bell code on a local instruction for instance.
 

furnessvale

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Indeed. It's probably still in the rule book that repeated short blasts on the horn signifies a train in distress. But I wonder if something more than that was appropriate before deciding to divert a runaway train into the sand drag. There could have been a special bell code on a local instruction for instance.

I'm sure you are correct.

Anybody got an old copy of the sectional appendix for the Woodhead?
 
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