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Everything posted by Edwin_m

  1. I remember that 31 smoking the place out when it was started up in the RTC yard at Derby back in the 90s sometime.
  2. You could work out the maximum superelevation but not necessary the superelevation that was actually used [aside: from here I'll use "cant" instead as it means the same but is easier to type]. There is an "equilibrium speed" where a train going round a canted curve experiences no net lateral force and the wear on both rails will be equal. But trains may be going slower than that, and therefore wearing the inner rail more, or faster and wearing the outer rail more. So the choice of cant at a particular location depends on the mix of train speeds arising from stopping versus non-stop and also passenger versus freight, with tonnage also taken into account because a heavy train causes a lot of wear on the lower rail if it is going a lot slower than equilibrium speed.
  3. Cant on a model is purely for cosmetic effect, it doesn't help the trains go round curves (and it can hinder if the stock is uncompensated and the cant gradients are too abrupt). Because gravity doesn't scale, model trains can go happily round curves at speeds where the prototype would overturn. Generally speaking modern curves will be canted independently - that is that the lower rails of each track will be level with each other, rather than being in a common plane so the outer track is higher than the lower. This may not be so if there is a crossover or other pointwork on the curve between the two tracks in question, but that sort of layout is avoided where possible as it's difficult to maintain and may cause a lower speed restriction for trains on the principal route. If a junction on a curve is optimised for trains on one route, then those on the other route may encounter reduced or even negative cant, which will lead to a severe speed restriction (Sheet Stores Junction springs to mind).
  4. Best exhibition I have been to for some time - good selection of layouts and the local/secondhand traders and some specialist traders and demos without being swamped by the box shifters. I assume SVMRC have upped the size of this in response to the demise of the big event in Nottingham.
  5. Also of course if there were lots of spare trains and drivers hanging around in sidings, the public and the press would be asking why they aren't in service doing something about the overcrowding.
  6. Yes the 185s have an "eco mode" that shuts down each engine in rotation (to even up the wear on the engines). They have cross-feeding so the air-conditioning, lighting and other auxiliaries on the affected coach are supplied from the next one. The driver can select full power if needed to make up time.
  7. There is allegedly a government commitment to fund OLE improvements south of Bedford.
  8. Sounds like Reggie Perrin who was always 11 minutes late for a variety of reasons such as a badger eating a junction box.
  9. It is claimed they have the same performance on diesel as 222s, so as the 222s can reach 125mph then these new units will too. The diesel engines will power the same motors as are used in electric mode.
  10. I'm also getting the big grey band. When something similar happens with actual ads on other sites, I've usually scrolled down by the time it downloads. So the ad never gets viewed.
  11. Often I see an ad for the exact same product I browsed, so something more specific is going on than just categorising people's interests. Since the ad provider knows my detailed browsing history within the shopping site then it shouldn't be beyond them to include a check whether I actually bought the widget in question. Another annoying feature with that type of targeted advertising is that I might have looked at or bought an item as a present for a relative, only to have it popping up on screen when they are sitting next to me. As I say it hasn't happened here so is I suspect and hope that what Andy is using with Google is something else. But I'm on a different PC from usual so anything cookie-related or IP-related probably hasn't built up any history yet.
  12. I often find ads for some product I've considered buying, though not on this site as far as I recall. However they usually appear after I've bought the product from the supplier in the ad (surely they can check for that and save themselves some money?) or from someone else, or decided not to buy it at all.
  13. There's also particulate emissions from tyre and brake wear. Compared to an equivalent fossil-fuelled car an electric one may have less brake wear due to using regeneration, but more tyre wear as the battery makes it heavier.
  14. It's certainly a risk. I wonder how much CO2 is saved per public pound spent on electrifying railways versus the various subsidies directed at electric cars.
  15. There's still be some pressure difference though, even if it's less than a tenth of an atmosphere for a metre depth of fuel. The pressure differential between inside and the gas space will be less than one atmosphere as the upper part will contain some air (the tank wouldn't be completely full before unloading) and vapour (lower boiling point at low pressure!) so the difference between top and bottom could be perhaps 20% or more. This strikes me as enough to make the top significantly more likely to cave in.
  16. If the crossings have barriers only half way across the road then these are automatic types and do not require protecting signals. There will be a signal somewhere that can be put back to danger in emergency or if the crossing fails, but it may be a long way before the actual crossing. In normal working the train has clear signals and the crossing only closes when the train is fairly close to it and has probably already passed the last signal before. If the crossings have barriers the whole way across the road then they are one of the various manual types (including ones that normally work automatically with obstacle detectors but the signaller can intervene if necessary). With these the crossing has to be closed before the signals on the approach can be cleared. So there will be a signal not too far away to avoid closing the road for too long, but not necessarily right at the crossing where the old signals probably were.
  17. Northern Powerhouse Rail, if it happens, is talking about making drastic changes to Leeds-York, such as four-tracking between Leeds and Neville Hill and possibly even jumping onto the last bit of HS2 towards Church Fenton. This would involve big changes to the existing route which would be more difficult and costly if it had already been electrified. So it's probably not worth spending money on the existing route until it's known whether it would be affected or in part replaced by these more radical measures (and today's announcement on HS2 probably pushes back the date when that will be known). While NPR also proposes a completely new route between Manchester and Leeds, the situation here is a little different. The NPR proposal is via Bradford so wouldn't directly affect anything between Huddersfield and Dewsbury. There is still a risk of these enhancements being cancelled as unnecessary if the government suddenly goes forward with NPR - on the other hand if NPR doesn't go ahead enhancing the Huddersfield route is the only option left on the table.
  18. 8 miles on its own would be stupid, not least because it would need its own highly expensive feeder station or a 25kV cable from elsewhere. I believe the intention is to electrify from Huddersfield through to Leeds but not west of Huddersfield (where of course the gradients would give the greatest performance benefit...).
  19. There's probably some new standard a new design would have to follow so might not be possible to run more of the existing design - that's certainly the case with the contemporary Pendolinos. Another problem is that the longest train in the St Pancras MML platforms is 10 cars of 23m-ish, so electrifying the Meridians would have involved converting one car to electric (difficult) or scrapping it (expensive). This is the reason the Hitachi units will have a slightly shorter bodyshell than on ECML and GWML, and if the scheme had gone ahead it would probably have concentrated on the 4-car Voyagers that can be made up to 5-car without major platform issues on XC. There were also techno-political issues with Bombardier wanting to use their own traction equipment (made in Sweden) rather than the British-made Alstom equipment fitted to the existing units.
  20. Yes, the weight of the liquid in the lower part of the tank would make the pressure lower down closer to atmospheric, so if the tank is of uniform thickness it will always "go" towards the top where the pressure is least.
  21. I wonder if part of the problem was also taking power before the brakes through the train had fully released. I believe it was possible to break a coupling by doing so with a modern powerful locomotive such as a Class 60. Railwaysarchive seems to be a bit deficient on accident reports for a period in the 1990s and early 2000s which I think coincides with when HSE was responsible, between the demise of the traditional HMRI setup with its ex-military inspectors and the advent of RAIB. Many of the reports that are available from this period are markedly inferior to those from before or since.
  22. The option of coupling a diesel locomotive (a bit like the old Weymouth push-pull operation) was discussed at the time of original procurement of the IEP but it was decided to order a mix of straight electric units for the main routes and bi-modes for the non-electrified extensions. I think this was because of the risk of delays attaching the locomotive and probably also the loss of the various loco sidings that existed near major stations when loco changes were routine. With many of the off-wires runs being once or twice a day the locomotives might have ended up being rather numerous and poorly utilised. This decided, unsurprisingly Hitachi came up with a modular design where any of the intermediate cars could have a diesel power pack fitted (and indeed the straight electrics have some diesel power for low-speed emergency operation if the power is lost). So when the GW electrification was cut back and it became obvious that nearly every duty would involve operation off the wires, it was a relatively easy if not cheap decision to ask Hitachi to fit diesels to many of the cars not so fitted. There are still straight electric units in the ECML fleet. Incidentally Hitachi has now tweaked the design further for the Midland order. The cars are slightly shorter to fit the platform length at St Pancras and all the units are five cars with diesel engines in four of them and a transformer in the fifth. The various ECML and GWML versions didn't allow a diesel engine in the end cars.
  23. Certainly they should vent on over-pressure - anyone remember the concern about BLEVEs (boiling liquid expanding vapour explosion) back in the 70s? If the tank is exposed to an external heat source, venting of vapour even if it catches fire is probably preferable to the huge explosion (BLEVE closely followed by vapour-air) that could result if it was unvented and eventually failed.
  24. The wheel and track dimensions haven't changed significantly (new track was 3mm narrower for a couple of decades then went back to the traditional 1435mm). But my own theory is that you may be hearing the consequence of modern bogie dynamics. Above a certain speed any rail vehicle will zigzag from side to side as it runs along the track, known as hunting. This was analysed in the 1960s by British Rail Research and to counteract it most trains built from the 1970s onwards have dampers (shock absorbers) that resist the rapid rotation of the bogie that takes place during hunting. These can be seen mounted horizontally outside the bogie frame on many types of rolling stock, with brackets attaching one end to the bogie and the other end to the body. However these have the side-effect that the bogie doesn't line up as exactly with the track on curves, so there is more flange squeal.
  25. Someone mentioned the Digikeijs DR5000 a few posts back. I'm still wiring up but as far as I can tell the EB1s (kept from the previous setup and around 11 years old) are quick enough to cut out before the 5000.
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