Trap points on freight-only lines

[mike morley]

Were they required or not?

 

Much perusal of pictures has had ambiguous results.

On the Cromford and High Peak there might have been a set in one of the sidings at Minninglow (half hidden in the long grass just a little too well for me to be 100% sure that's what it actually is) and definitely one at Friden, but none in other places where, if they were required, they might have been expected. 

In the Forest of Dean there are plenty of photos featuring what might have been trap points but which, because of their various locations, might well have been catch points.  A further complication is that some of the pictures are quite old and what they feature could have been hang-overs from the days when passenger trains still ran in the Forest.  At Serridge Junction there was what was quite definitely a set of trap points on the Crown siding (And totally unnecessary they were, too!  The siding dropped away very sharply from the connection with the main line and gravity did far, far more than a set of trap points could possibly do to prevent rolling stock making an unauthorised exit!) but as that was a private siding I wonder if the regulations were different for them.  That Killer's Siding, a private siding on the Cromford and High Peak, lacked a set of trap points where it joined the 'main' line at Steeplehouse is another ambiguity.

[Grovenor]

Being required and being provided are two different things.

The Board of Trade/Ministry of Transport docunent was quite clear, Requirements for Passenger Lines, Recommendations for Goods Lines. None of which stopped you putting in more of them if you wanted to. Risk analysis has been long practiced even if not so labelled.

Edited May 2, 2020 by Grovenor

[Tanllan]

It really depends on the circumstances. If you need to protect your running line from errant movements on branches or sidings then traps are appropriate. From my childhood holidays, at my maternal grandparents home, I can remember that where the Eston branch crossed Flats Lane there were trap points to prevent movements onto the level crossing.

By the time I was old enough to be allowed to roam alone there was but one train a day and the signal box, etc., had been removed. On the west side of the crossing there was a single set of traps but on the other side each of the three lines had a set of traps - all worked by local levers - big heavy 'throw over' types or NER origin. See link to map for context.
<https://maps.nls.uk/view/125623774>

 

As for the Killers Branch on the C&HP - (which features a narrow steep sided cutting and hence damp/slippery rails) I understand that the loco often had trouble controlling the loaded trains heading for the 'main line' - if traps had been provided then the local breakdown gang would probably have been there on a regular basis.

 

[mike morley]

18 minutes ago, Tanllan said:

As for the Killers Branch on the C&HP - (which features a narrow steep sided cutting and hence damp/slippery rails) I understand that the loco often had trouble controlling the loaded trains heading for the 'main line' - if traps had been provided then the local breakdown gang would probably have been there on a regular basis.

Surely a good reason to install a catch point that would double as a trap point?

 

On the other hand, Flatts Lane Junction looks extremely interesting.  I assume what the map shows as a 'coal depot' was actually a landsale yard?

[Tanllan]

On 02/05/2020 at 21:26, mike morley said:

Surely a good reason to install a catch point that would double as a trap point?

 

On the other hand, Flatts Lane Junction looks extremely interesting.  I assume what the map shows as a 'coal depot' was actually a landsale yard?

Mike,

 

My understanding of a 'Catch Point' is a set of points that are sprung loaded that are designed to deliberately derail a vehicle/train making a 'wrong line' movement or is out of control on a 'running line'. e.g <https://www.google.co.uk/maps/@54.4008993,-0.7125305,3a,44.8y,16.9h,90.47t/data=!3m6!1e1!3m4!1sXCULP0sIEwUzt-RLJbInaQ!2e0!7i13312!8i6656!5m1!1e1>

To make a facing movement over Catch Points a shunter or other appointed person has to hold the points closed during the movement. Whereas Trap Points can be set to pass through in either direction. If catch points had been provided at Flatts Lane LC an additional person would have been required to assist the guard during the busy shuntling activity that used to take place at this junction.

The coal depot on the map was a domestic coal merchants yard. Being on NER territory there was a set of coal drops.

[micknich2003]

The attached drawing of King George Dock may be of interest, the entire layout was goods only and as can be seen there were no trap points at any of the junctions. Though as can be seen to the left of the drawing the H&B Sidings were trapped, No48.

[Edwin_m]

9 hours ago, Tanllan said:

Mike,

 

My understanding of a 'Catch Point' is a set of points that are sprung loaded that are designed to deliberately derail a vehicle/train making a 'wrong line' movement or is out of control on a 'running line'. e.g <https://www.google.co.uk/maps/@54.4008993,-0.7125305,3a,44.8y,16.9h,90.47t/data=!3m6!1e1!3m4!1sXCULP0sIEwUzt-RLJbInaQ!2e0!7i13312!8i6656!5m1!1e1>

To make a facing movement over Catch Points a shunter or other appointed person has to hold the points closed during the movement. Whereas Trap Points can be set to pass through in either direction. If catch points had been provided at Flatts Lane LC an additional person would have been required to assist the guard during the busy shuntling activity that used to take place at this junction.

There was such a thing as a "worked catch point" which could be set in much the same way as a standard point to allow a train to pass in the facing direction, but would otherwise operate as a sprung catch point.  These were used, for example, on some single line gradients.  

[jim.snowdon]

On 06/05/2020 at 08:25, Edwin_m said:

There was such a thing as a "worked catch point" which could be set in much the same way as a standard point to allow a train to pass in the facing direction, but would otherwise operate as a sprung catch point.  These were used, for example, on some single line gradients.  

As I understand it, a "catch point" is a locally worked switch (or pair of switches) whose purpose is to "catch" portions of trains running away in the wrond direction. Their use is on long gradients to prevent parts of trains running back into the previous block section, and thus permitting an intermediate block box part way up the gradient to function effectively. Line clear can be given for the lower part of the gradient once it is known that the previous train has cleared the catch points, which would be sited in advance of the clearing point for the intermediate's Home signal, safe in the knowledge that if the previous train runs away in the wrong direction the pile of (derailed) vehicles will be beyond the clearing point.

 

"Trap points" are, to my understanding, always worked points and incorporated in the interlocking, their purpose being to prove that a wrong movement on the "trapped" road cannot reach the running line into which it would otherwise converge. The common factor between the two is that they are intended to protect against collisions due to unauthorised movements.

 

Jim

[Edwin_m]

50 minutes ago, jim.snowdon said:

As I understand it, a "catch point" is a locally worked switch (or pair of switches) whose purpose is to "catch" portions of trains running away in the wrond direction. Their use is on long gradients to prevent parts of trains running back into the previous block section, and thus permitting an intermediate block box part way up the gradient to function effectively. Line clear can be given for the lower part of the gradient once it is known that the previous train has cleared the catch points, which would be sited in advance of the clearing point for the intermediate's Home signal, safe in the knowledge that if the previous train runs away in the wrong direction the pile of (derailed) vehicles will be beyond the clearing point.

 

"Trap points" are, to my understanding, always worked points and incorporated in the interlocking, their purpose being to prove that a wrong movement on the "trapped" road cannot reach the running line into which it would otherwise converge. The common factor between the two is that they are intended to protect against collisions due to unauthorised movements.

 

Jim

Generally yes, although I think the catch points might actually be in advance of the section signal.  Otherwise with a train in the section with the gradient there would be nothing to stop the signaler bringing a second train forward over the catch points to wait at that signal, where it would be in danger of being struck by a rollback.  No doubt there's someone on here with a definitive view on that, er, point.  

 

The block post wouldn't necessarily have to be on the gradient to need a catch point, just close enough to it that there was a risk of a rollback getting as far as the next train.  

[jim.snowdon]

31 minutes ago, Edwin_m said:

Generally yes, although I think the catch points might actually be in advance of the section signal. 

I agree. I thought of that afterwards, but left the post as written. In advance of the Section signal would be more logical.

 

32 minutes ago, Edwin_m said:

The block post wouldn't necessarily have to be on the gradient to need a catch point, just close enough to it that there was a risk of a rollback getting as far as the next train.  

True. In my defence, I had the example of Shap, and Scout Green box, in my head at the time.

 

Jim

[The Stationmaster]

23 hours ago, Edwin_m said:

Generally yes, although I think the catch points might actually be in advance of the section signal.  Otherwise with a train in the section with the gradient there would be nothing to stop the signaler bringing a second train forward over the catch points to wait at that signal, where it would be in danger of being struck by a rollback.  No doubt there's someone on here with a definitive view on that, er, point.  

 

The block post wouldn't necessarily have to be on the gradient to need a catch point, just close enough to it that there was a risk of a rollback getting as far as the next train.  

Catch points were installed where the gradient was such that a breakaway would lead to vehicle rolling back to a location where they might come into collision with other vehicles.  The Requirements referred to them only in connection with 'steep gradients' (i.e. a gradient steeper than 1 in 260) but the Railway Companies etc would also install them on less steep gradients where they perceived a risk to be exist.   Additionally on long gradients a number of catch points would usually be installed  The requirements also said where catch points were being provided in the vicinity of stop signals the catch points should be more than a train length in rear of the signal in order to avoid derailments as a result of vehicles on a stationary train rolling back.

 

Clearly from a safety viewpoint it also made sense, particularly, on long or steep gradients, to install catch points some way in advance of block posts and their Section Signals to avoid runaways unnecessarily damaging infrastructure or colliding with a following train.  The provision and siting of catch points on single lines is obviously a rather different area.  The simplest way of doing the job was to install them in a crossing loop so they would normally be trailed and sensibly/obviously in advance of the signal controlling the exit from that loop.  There would then be a Signalbox Instruction requiring the loop points to be left set as they were for a departing train until 'Train Out of Section' was received from the signal box in advance.  Sometimes there was no option but to site the catch point in the single line and there was an example of this at Abercynon after the line between there and Black Lion had been singled where there was over a mile of rising gradients varying between 1in 8 and 1in 80 with the bulk of the distance at 1in 42 and which required a long sand drag in order to, hopefully, stop any runaways before they did any damage to Abercynon station - so very definitely a partially worked catch point using what the (G)WR called 'a slotted joint' that allowed the point to be trailed in the normal manner but equally allowed it to be closed and bollted for a facing movement.

Edited May 9, 2020 by The Stationmaster

[RailWest]

>>>The requirements also said where catch points were being provided in the vicinity of stop signals the catch points should be more than a train length in rear of the signal in order to avoid derailments as a result of vehicles on a stationary train rolling back.

 

A common example would be at place where a station/signal-box was at the top of a long gradient, in such a position that any train stopped at the Home signal would be on the downhill slope. A catch-point would be located 'more than a train length' in rear of that signal so that, in the event of a coupling failure when an unfitted train started to pull away again after the signal was cleared, the rear portion of the train would not roll very far backwards before being derailed. Examples which come to mind existed at Midsomer Norton (South) and Mortehoe & Woolacombe.

[The Stationmaster]

3 hours ago, RailWest said:

>>>The requirements also said where catch points were being provided in the vicinity of stop signals the catch points should be more than a train length in rear of the signal in order to avoid derailments as a result of vehicles on a stationary train rolling back.

 

A common example would be at place where a station/signal-box was at the top of a long gradient, in such a position that any train stopped at the Home signal would be on the downhill slope. A catch-point would be located 'more than a train length' in rear of that signal so that, in the event of a coupling failure when an unfitted train started to pull away again after the signal was cleared, the rear portion of the train would not roll very far backwards before being derailed. Examples which come to mind existed at Midsomer Norton (South) and Mortehoe & Woolacombe.

The biggest problem with catch points at stop signals was trains rolling back - especially if the points were not re-sited when length limits were increased.  That caused far more derailments than breakaways and was I understand, one of the reasons put forward for removing catch points.