59004 ( was Shedcombe....) Posted October 22, 2009 Share Posted October 22, 2009 Hi all, I was not familiar / known with catchpoints, until I started interest in / and modelling UK railway. Am I right in thinking that there are two basic versions, one with only one switched/diverging rail, and one with two switched/diverging rails ? I've recently come accross two sitiations where the function of a catch point, or the catch point as such, is done differently. I'd like to know what types were and are common ( or not ) where they saw/see use ( in terms of era's, area's and track types / standards ). ------------------------------- First is a situation within the exit throth of a yard towards the mainline, where IMO both joining roads are " guarded " against runaways towards the mainline, with the remains of a double slip. The route coming from the right can be gaurded to run further, by setting the remains of the old double slip to the left. The route coming from the left can be quarded to run further, by setting the remains of the double slip straight on. Comments please. ------------------------------- Second situation is a screen capture from a green diesels era video on YouTube. The train is Maroon Mk1's with a Green Peak on the front. Location unknown. The track on the left, is that a slow in one direction, in two directions, a siding ? Anyway, there's a crossover to the mainline. But there's also a " catchpoint " solution on that track after the crossover, where the diverging route is not just a catchpoint, but a diverging track to a bufferstop. Comments here as well please. Regards, Michel Link to post Share on other sites More sharing options...
Glorious NSE Posted October 22, 2009 Share Posted October 22, 2009 Suspect the first one is the re-use/modification of the existing double slip to that function, after one of the tracks has been removed (it would have run between the wall and the hut I suspect) - no need to alter any track or signalling that way. A short track ending in a bufferstop is fairly common in a yard type scenario, it lets you use the track as a mini-headshunt clear of the main line whilst also filling the catch point function. On the London end of the WR there was another version of the 2-rail one, where the 'outer' rail of the curve lifts up and drops the wheel over the top of the opposite running rail, that means that when something derails on it, it can't be guided back to the main line by the running rails... Link to post Share on other sites More sharing options...
Fat Controller Posted October 22, 2009 Share Posted October 22, 2009 Suspect the first one is the re-use/modification of the existing double slip to that function, after one of the tracks has been removed (it would have run between the wall and the hut I suspect) - no need to alter any track or signalling that way. What isn't easily apparent in the first photo is that the ground between the wall and the hut is slightly higher than that between the wall and the mainline- the track over it acted as a hump for shunting purposes. Hump shunting stopped by the late 1960s/early 1970s here (Bristol East Depot, Up Yard) A short track ending in a bufferstop is fairly common in a yard type scenario, it lets you use the track as a mini-headshunt clear of the main line whilst also filling the catch point function. The west end of Alexandra Dock Junction has this arrangement, with not one, but two double slips. They generally serve to stable track machines. Link to post Share on other sites More sharing options...
Edwin_m Posted October 22, 2009 Share Posted October 22, 2009 In modern parlance your first photo is a "trap point" not a "catch point", though the two names have been used more interchangeably in the past. The purpose of a trap point as you say is to derail an unauthorised move coming out of a siding or yard before it can foul a running line. Today a "catch point" is intended to derail a portion of a train that might have broken away and rolled back down a gradient. With all trains now having automatic brakes catch points have pretty much disappeared from the modern network. Your second photo is more interesting. I think the left hand track is a slow line, because if it is a siding there would probably be a signal close to the points to control the exit onto the main line. A slow line would usually have the signal further back, in fact the photographer may have climbed up the signal! If the left hand track runs on into a siding or yard in the distance, then this would be another trap point to prevent anything rolling out of the yard onto the slow line. However it could also be a catch point. If the gradient is ascending away from the camera then if a train on the left hand split into two, the rear portion would be derailed before coming into conflict with a following train routed over the crossover onto the middle track. Without either knowing where this is or having a much better photo it is not possible to tell which of the two this is - unless anyone has any better ideas!? Link to post Share on other sites More sharing options...
Miss Prism Posted October 22, 2009 Share Posted October 22, 2009 My initial reaction on the second photo was also that it was probably a gradient catch. Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted October 22, 2009 RMweb Gold Share Posted October 22, 2009 As already noted the remnant of a double slip in the top picture is in Bristol East Depot Up Yard and led to the hump (remains visible on the bottom right) and was left as a handpoint to serve two directions (from the direction of view - if you look closely the switches at the other end have been removed). The trap point from the yard is out of view in the bottom right hand corner. The lower picture shows what is basically a Goods/Slow line running connection into the adjacent running line with the line going ahead protected by what is most likely a trap point. Now to basics - there are two sorts of points involved - a trap point and a catch point. A trap point is a facing point which is there to trap any movements/vehicles illegitimately trying to make their way out onto a running line and such things used to be manadatory where sidings or goods only lines joined a passenger line (they still are in many circumstances). The other thing about a trap point is that it has a protecting signal and it is worked from a signal box or ground frame. It has been part of the Dept of Transport 'requirements' since at least 1950 (and probably earlier) for a trap point to have two switch rails. A catch point is (usually) a trailing point used to catch breakaways running away in the wrong direction in order to prevent them from running back and colliding with a following train - accordingly catch points are found on rising gradients and usually only had a single switch rail although some can nowadays can be found with two switch rails. Most catch points have vanished from the British scene as they were really associated with loose coupled freights (where the rear portion would not automatically stop if it broke away). In some instances of 1970s resignalling power operated catch points (with two switch rails) were used in specialised operational circumstances. The terms 'trap' and 'catch' point are probably some of the most frequently confused bits of terminology in British railway usage and indeed if you go back to the Pre-Group era you will find that they were even officially confused and that some Railways used the term 'catch point' to cover both circumstances. They were officially clarified and defined at some time in the inter-war years (I think the mid 1920s). Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted October 22, 2009 RMweb Gold Share Posted October 22, 2009 In modern parlance your first photo is a "trap point" not a "catch point", though the two names have been used more interchangeably in the past. The purpose of a trap point as you say is to derail an unauthorised move coming out of a siding or yard before it can foul a running line. Today a "catch point" is intended to derail a portion of a train that might have broken away and rolled back down a gradient. With all trains now having automatic brakes catch points have pretty much disappeared from the modern network. Hi Edwin, The terms you are describing refer to the function of the points, i.e. the terms used by the signalling and operating staff. The physical object was nearly always known to permanent way staff as catch points, and was described as such on the manufacturing drawings. So you can say "a set of catch points was installed in the siding as trap points". But trap points don't have to be catch points. Often a full turnout is used as trap points, leading to a short spur or sand drag. regards, Martin. Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted October 22, 2009 RMweb Gold Share Posted October 22, 2009 I was not familiar / known with catchpoints, until I started interest in / and modelling UK railway. Hi Michel, There are three pages of discussion about catch points on Old RMweb: http://www.rmweb.co....opic.php?t=8908 And on Templot Club: http://85a.co.uk/for...179&forum_id=11 regards, Martin. Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted October 22, 2009 RMweb Gold Share Posted October 22, 2009 Hi Edwin, The terms you are describing refer to the function of the points, i.e. the terms used by the signalling and operating staff. The physical object was nearly always known to permanent way staff as catch points, and was described as such on the manufacturing drawings. So you can say "a set of catch points was installed in the siding as trap points". But trap points don't have to be catch points. Often a full turnout is used as trap points, leading to a short spur or sand drag. regards, Martin. er no - all the permanent way design and maintenance staff I have ever had any dealings with (over more than 30 years) knew full well the difference between trap and catch points and it has certainly been correctly used on any PW drawings I have ever seen; indeed it is rather critical to show it correctly on 40ft:1" (or metric equivalent)drawings because they are used for detail signalling design. The terminology was set a long time ago by the railway industry and the Dept of Transport and applies to the railway as a whole, not just to one part of it. (and as those of us involved with such things for our living over many years know all too well it is always the safest course to avoid loose use of terminology because that can, and does, lead to trouble). However as I have already pointed out there was an earlier practice on some parts of the railway of referring to all such points as catch points and no doubt that lingered with some for many years after it ceased to be the official way of things. Nowadays everything is perfectly clear the few remaining catch points are that and trap points are something else. Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted October 22, 2009 RMweb Gold Share Posted October 22, 2009 The terminology was set a long time ago by the railway industry and the Dept of Transport and applies to the railway as a whole, not just to one part of it. Hi Mike, I suppose it depends what you mean by "a long time ago". For those modelling the traditional bullhead/steam era, 30 years is recent. "British Railway Track - Design, Construction and Maintenance", the "bible" published by the Permanent Way Institution: 3rd Edition, 1964, much bullhead-based information, refers to "Catch Points" throughout. All the bullhead track drawings I have seen are labelled "Catch Points". 4th Edition, 1971, mostly flat-bottom information, has had all relevant references changed to "Trap Points". So maybe, if it's bullhead, the physical track object is called a "set of catch points". If it's flat-bottom, it's called a "set of trap points"? But if you call a short derailer switch in a siding "a set of trap points", what do you call a full turnout used as a trap? It's just as confusing to have two meanings for the same word as it was before. Martin. Link to post Share on other sites More sharing options...
59004 ( was Shedcombe....) Posted October 22, 2009 Author Share Posted October 22, 2009 Hi Martyn, Brian, Edwin, Miss Prism, Mike and Martin, Thanks so much for all thorough responses and discissions. I've learned a bit more, and hope to continue to do so. Will check the other links on the subject. Regards, Michel Link to post Share on other sites More sharing options...
RMweb Gold The Stationmaster Posted October 22, 2009 RMweb Gold Share Posted October 22, 2009 Hi Mike, I suppose it depends what you mean by "a long time ago". For those modelling the traditional bullhead/steam era, 30 years is recent. "British Railway Track - Design, Construction and Maintenance", the "bible" published by the Permanent Way Institution: 3rd Edition, 1964, much bullhead-based information, refers to "Catch Points" throughout. All the bullhead track drawings I have seen are labelled "Catch Points". 4th Edition, 1971, mostly flat-bottom information, has had all relevant references changed to "Trap Points". So maybe, if it's bullhead, the physical track object is called a "set of catch points". If it's flat-bottom, it's called a "set of trap points"? But if you call a short derailer switch in a siding "a set of trap points", what do you call a full turnout used as a trap? It's just as confusing to have two meanings for the same word as it was before. Martin. Hi Martin, All sorts of differences in usage I suspect Martin. The 'requirements' separated trap and catch in the 1950 edition but at present I can't lay hands on the 1925/27 edition to see what it says on the subject. I was definitely working with PW blokes in the '70s who referred to them as trap or catch appropriate to their use although I don't think I've got any large scale PW drawings earlier than 1990s to see what they might, or might not, say. As to what is actually there the situation then becomes so mixed as to leave almost no constructional arrangement not involved As you probaby know by 1950 - if not earlier - trap points were required to have a pair of switches (known by most PW men of my acquaintance as 'double tongue') but what went on beyond the switches varied entirely according to site and, I suspect, sometimes according to Drawing Office or local PW Inspector whim - but in all cases the switches were serving as a trap and were/are called a 'point' even if they are no more that switches. But then equally for many years the vast majority of catch points only had one switch rail but going back a hundred years always seem to have been referred to as 'catch points' or 'runaway catch points' and on some Railways had signs referring to them as such. So I think really the name is probably nowadays more firmly linked to purpose (where it has Rule Book and maintenance connotations as well of course) than to constructional detail). Thus if it is there to act as a trap - which means it will almost invariably have some sort of signalling and detection - then it is called a trap. PS Totally irrelevant here but thanks for the link the other day to 'new posts', alas for some reason all my attempts to reply on that thread vanished when I pressed the button! Link to post Share on other sites More sharing options...
59004 ( was Shedcombe....) Posted October 23, 2009 Author Share Posted October 23, 2009 PS Totally irrelevant here but thanks for the link the other day to 'new posts', alas for some reason all my attempts to reply on that thread vanished when I pressed the button! Hi Mike, All of use on the forum suffered from that briefly. Another annoying, and luckily brief, glitch. Regards, Michel Link to post Share on other sites More sharing options...
RMweb Gold beast66606 Posted October 25, 2009 RMweb Gold Share Posted October 25, 2009 Michel, can you provide a link to the YouTube video ? ta Link to post Share on other sites More sharing options...
59004 ( was Shedcombe....) Posted October 25, 2009 Author Share Posted October 25, 2009 Hi Dave, Of course I can. There are more nice video's from the same person ). The mentioned situation is in a shot about 5.10 to 5.20 minutes. Regards, Michel Green Diesels video on Youtube Link to post Share on other sites More sharing options...
RMweb Gold beast66606 Posted October 25, 2009 RMweb Gold Share Posted October 25, 2009 Hi Dave, Of course I can. There are more nice video's from the same person ). The mentioned situation is in a shot about 5.10 to 5.20 minutes. Regards, Michel Green Diesels video on Youtube Cheers, Link to post Share on other sites More sharing options...
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