Pacific231G Posted October 13, 2016 Share Posted October 13, 2016 (edited) Fascinating. One "point" though - points with a single movable blade don't need this track scheme - it's not unknown historically on tramways using normally flanged wheels (in both real and model form). That's true and tends to confirm my theory that cost saving rather than any simplification was the objective. I wonder if the flangless wheel was also used to reduce friction on small radius curves? Would it also have been free to rotate on the axle? It's possible but the bogie is a standard one with a particularly short wheelbase designed to go round the tightest curves. From various photos of the bogie and its known dimensions (730x730 mm) and gauge (500mm) I would estimate its wheelbase to be between 300-350mm. which should manage a minimum curve of 3 or 4 metres. I think the sharpest curves that Decauville normally supplied ex. stock for 50cm were of 4 metres radius and I think the sharpest curves I saw in the museum would be about that. Any tighter and they used turntables. Apart from the missing flange on one wheel the wheelsets were standard Decauville types with axle boxes so I think the wheels were fixed but wouldn't swear to that. I've tried to find some original documentation on the railway but with no luck so far. Edited December 21, 2016 by Pacific231G Link to comment Share on other sites More sharing options...
Talltim Posted December 21, 2016 Share Posted December 21, 2016 (edited) Dual gauge junction in Columbus Ohio. 4'8 1/2" and 5' 2". The lines to the right appear to be 5' 2" only http://www.columbusrailroads.com/new/?menu=Home Edited December 21, 2016 by Talltim 4 Link to comment Share on other sites More sharing options...
RMweb Premium Ian Smeeton Posted February 26, 2017 RMweb Premium Share Posted February 26, 2017 (edited) Not sure of the gauge in this one, but it might make a useful Cameo on someone's dockside lyout. Link to the whole photo here: http://www.britainfromabove.org.uk/image/sar018768 Regards Ian Edited February 26, 2017 by Ian Smeeton 2 Link to comment Share on other sites More sharing options...
RMweb Premium Compound2632 Posted March 18, 2017 RMweb Premium Share Posted March 18, 2017 A must-see: Nearholmer's post linking to film of a most entertaining dual-gauge flat crossing... 2 Link to comment Share on other sites More sharing options...
DavidBird Posted April 3, 2017 Share Posted April 3, 2017 (edited) What about this here, from ColinK on the "Prototype for everything?" thread... How about this piece of trackwork? IMG_7495.jpg Edited April 3, 2017 by DavidBird 2 Link to comment Share on other sites More sharing options...
ejstubbs Posted April 3, 2017 Share Posted April 3, 2017 A must-see: Nearholmer's post linking to film of a most entertaining dual-gauge flat crossing... That's not flat: I reckon there's a good six inches difference in elevation between the crossing tracks. I'm impressed that they made sure to run their CMX track cleaner through as soon as the line was open. Link to comment Share on other sites More sharing options...
John ks Posted April 10, 2017 Share Posted April 10, 2017 What about this here, from ColinK on the "Prototype for everything?" thread... This was or will be a common rail transition point in a duel gauge track The wider gauge rail (red rail in drawing) has been removed or yet to be installed John Link to comment Share on other sites More sharing options...
John ks Posted April 10, 2017 Share Posted April 10, 2017 Here are some images from Roma St station in Brisbane Australia At first glance it may look like a normal double crossover The LH point that splits the duel gauge straddled track into standard (straight) & NG(narrow gauge) (diverging to the left) has 2 flexible point blades The image shows it in the straight position The closer blade moves (flexes) to the running rail & the further blade moves away from the running rail, setting the point to the diverging NG track This is a close up of the rest of the point on the left middle of the above photo This is looking the other way My understanding is. The duel gauge track on the right with the common rail is used to run around standard gauge locos (Last time I looked the interstate trains were the XPT, Aussie equivalent to the intercity 125 making loco run-around's rare) The duel gauge track on the left where the standard gauge straddles the narrow gauge is the platform where inter-state trains arrive and depart Suburban electrics also use this platform My best guess for the gauges to be straddling each other is so that different gauge coaches can use the same platform & still be at the correct distance from the platform John 3 Link to comment Share on other sites More sharing options...
RMweb Gold Budgie Posted April 10, 2017 RMweb Gold Share Posted April 10, 2017 Here are some images from Roma St station in Brisbane Australia ... I'd love to see someone make a model of that. Link to comment Share on other sites More sharing options...
BG John Posted April 10, 2017 Share Posted April 10, 2017 I'd love to see someone make a model of that. It was the birthday of a famous British engineer who provided plenty of opportunity for modelling complex mixed gauge track yesterday. That example from down under is pretty basic in comparison . 1 Link to comment Share on other sites More sharing options...
RMweb Gold The Johnster Posted April 23, 2017 RMweb Gold Share Posted April 23, 2017 Did the sun shine through Box Tunnel from one end to the other when it rose that morning? (According to Wikipedia this is a myth, but I worked with a driver who claimed to have seen it. It's the sort of stunt he'd have pulled though, especially given his interest in ancient Egypt and some of the alignments in pyramids and temples) Link to comment Share on other sites More sharing options...
DavidBird Posted April 23, 2017 Share Posted April 23, 2017 Here are some images from Roma St station in Brisbane Australia... IMG_0419a.jpg My understanding is. The duel gauge track on the right with the common rail is used to run around standard gauge locos (Last time I looked the interstate trains were the XPT, Aussie equivalent to the intercity 125 making loco run-around's rare) The duel gauge track on the left where the standard gauge straddles the narrow gauge is the platform where inter-state trains arrive and depart Suburban electrics also use this platform My best guess for the gauges to be straddling each other is so that different gauge coaches can use the same platform & still be at the correct distance from the platform John If the 4'8.5" is outside the 3'6", "so that different gauge coaches can use the same platform & still be at the correct distance from the platform" does that mean that the narrow gauge coaches are actually wider than the standard gauge ones? Link to comment Share on other sites More sharing options...
RJS1977 Posted April 23, 2017 Share Posted April 23, 2017 Did the sun shine through Box Tunnel from one end to the other when it rose that morning? (According to Wikipedia this is a myth, but I worked with a driver who claimed to have seen it. It's the sort of stunt he'd have pulled though, especially given his interest in ancient Egypt and some of the alignments in pyramids and temples) As the line through Box Tunnel was under possession on the day in question, several NR and FGW engineers went to have a look. Their conclusion was that the tunnel and its approach cuttings had clearly been designed with that in mind, however although the sun shone a long way into the tunnel, it didn't shine right through. One of the engineers mentioned that the tunnel had been relined at some point in the past which may have affected things. I read a while back (can't remember where) that the sun does indeed shine through, but a couple of days later as atmospheric pollution has affected the refractive index of the atmosphere since Brunel's day. Link to comment Share on other sites More sharing options...
RMweb Premium Compound2632 Posted April 23, 2017 RMweb Premium Share Posted April 23, 2017 As the line through Box Tunnel was under possession on the day in question, several NR and FGW engineers went to have a look. Cause or effect? i ought to go away and calculate if the axial precession - 5 arcseconds per century - is enough to have destroyed the effect Brunel is supposed to have intended by now. Link to comment Share on other sites More sharing options...
John ks Posted April 24, 2017 Share Posted April 24, 2017 If the 4'8.5" is outside the 3'6", "so that different gauge coaches can use the same platform & still be at the correct distance from the platform" does that mean that the narrow gauge coaches are actually wider than the standard gauge ones? I haven't got access to prototype data but I took width measurements from some models I own HO QR NG diesel 32.2mm HO NSW SG diesel 34mm HO Class66 32mm OO Class 66 35.8mm OO intercity 125 36.2mm While these widths may not be 100% accurate they show that the NG & SG stock are close to the same width The suburban electrics have a 100mm lip/platform at floor level at each doorway that effectively widens the coach by 200mm Because both gauge coaches are approximately the same width then the centreline of the coaches have to be the same distance from the edge of the platform The way to do this is to have the both gauges on the same centreline hence the SG straddles the NG Hope this is a bit clearer then mud John Link to comment Share on other sites More sharing options...
DavidBird Posted April 24, 2017 Share Posted April 24, 2017 ... Because both gauge coaches are approximately the same width then the centreline of the coaches have to be the same distance from the edge of the platform The way to do this is to have the both gauges on the same centreline hence the SG straddles the NG Hope this is a bit clearer then mud John Sorry, brain-freeze there. Of course, the same centre-line of the two gauges means they're the same width... Link to comment Share on other sites More sharing options...
jim.snowdon Posted June 11, 2017 Share Posted June 11, 2017 It's been done many times already, and some of the first generation systems had trolleybuses with sufficient on board battery capacity to make short moves off-wire. Even then, trolleybuses can cope quite well with roadworks and where a major deviation from the normal line is required, it is not that difficult to temporarily realign the wires. Road works that major should be known about in advance anyway. Jim Link to comment Share on other sites More sharing options...
RMweb Premium Coryton Posted June 11, 2017 RMweb Premium Share Posted June 11, 2017 (edited) My understanding is. The duel gauge track on the right with the common rail is used to run around standard gauge locos (Last time I looked the interstate trains were the XPT, Aussie equivalent to the intercity 125 making loco run-around's rare) The duel gauge track on the left where the standard gauge straddles the narrow gauge is the platform where inter-state trains arrive and depart And at the southern end of the XPT network (Melbourne Southern Cross), the trains finish up on a platform with dual gauge standard and broad gauge track. You can't travel between the two on one service, but so far as I know the same trains are used on both routes - I wonder where else the same train routinely uses both narrow and broad gauge dual gauge track? And to go back to what started this off, there is (or was) a transition taking the standard gauge common rail from one side to the other on the dual gauge track in Melbourne Southern Cross. I probably have a photograph somewhere... Edited June 11, 2017 by Coryton Link to comment Share on other sites More sharing options...
Jenny Emily Posted June 16, 2017 Share Posted June 16, 2017 This was or will be a common rail transition point in a duel gauge track The wider gauge rail (red rail in drawing) has been removed or yet to be installed duel.jpg John Wouldn't it also work as a trap point in both directions? Link to comment Share on other sites More sharing options...
Grovenor Posted June 16, 2017 Share Posted June 16, 2017 Wouldn't it also work as a trap point in both directions? No its a fixed point unit, no moving parts. Regards Link to comment Share on other sites More sharing options...
RMweb Gold phil_sutters Posted June 19, 2017 RMweb Gold Share Posted June 19, 2017 (edited) Perhaps not quite the right thread, but these fossilized remains do seem to have preserved a slightly unusual bit of track, near the entrance inside Portsmouth Historic Dockyard. There are a few other bits around the site and a handful of goods wagons marooned on the quayside. Edited June 19, 2017 by phil_sutters 1 Link to comment Share on other sites More sharing options...
RMweb Premium Compound2632 Posted June 19, 2017 RMweb Premium Share Posted June 19, 2017 (edited) Perhaps not quite the right thread, but these fossilized remains do seem to have preserved a slightly unusual bit of track, near the entrance inside Portsmouth Historic Dockyard. There are a few other bits around the site and a handful of goods wagons marooned on the quayside. Preserved inset track Portsmouth 5 4 2017.jpg Isn't this just a conventional point but with a sort of continuous check rail to frame the setts? The check rail is joggled to give room for the switch blade to move. The resulting flangeway groove has been filled in. Edited June 19, 2017 by Compound2632 Link to comment Share on other sites More sharing options...
RMweb Gold Re6/6 Posted June 22, 2017 Author RMweb Gold Share Posted June 22, 2017 lnteresting interlaced track in Portsmouth. Amazing that it has lasted so long. 4 Link to comment Share on other sites More sharing options...
Memphis32 Posted June 23, 2017 Share Posted June 23, 2017 Is that broad gauge? Link to comment Share on other sites More sharing options...
RailWest Posted June 23, 2017 Share Posted June 23, 2017 No, just two interlaced (over-lapping) standard-gauge tracks. Link to comment Share on other sites More sharing options...
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