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Edwin_m

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Everything posted by Edwin_m

  1. Thanks for that … must have been thinking of the traditional mixed trains where the coaches had to be next to the loco.
  2. There are a couple of highly unusual exceptions which just might be relevant here, the carriage of containers to the Far North or West Highland sometime in the 80s (don't recall when or which or maybe it was both), and the "slip and brake" tests that used to be done north of Crewe. In both cases a dual-braked loco hauled one or more vacuum-braked but air-piped coaches with one or more air-braked wagons coupled behind. There are also translator coaches that allow dead multiple units with various electrically controlled braking systems to be hauled and braked by locomotives with a simple air brake, and in theory I guess one of these could be built to convert vacuum into air brake operation.
  3. Not strictly in line with the formations you have quoted, but worth bearing in mind a lot of Cross Country formations split and joined at Carstairs (and some of these also at Preston) so needed to have two brakes in the formation. These included the last BFKs (Mk2d) although those were used to segregate the first class passengers from passing plebs rather than anything to do with the brake area.
  4. Going by The Stationmaster's quote, 40 wheels is only five coaches and the gradient rules might reduce this to three or two (at least carrying passengers). Depending on route many formations wouldn't be allowed to have one brake located at one end and a few wouldn't even be allowed to have one in the middle. Rules also differed on other Regions and the position of the brake might also have been constrained by any short platforms along the route. I believe in 1972 all these rules were swept away and the brake could be anywhere in a passenger train.
  5. Not sure why counting to 40 in twos should be easier than counting to 20 in ones. Unless you're Noah.
  6. I imagine for a new commercial service the accessibility rules will apply, possibly subject to exceptions if existing stock is being used and is marginally non-compliant. The most visible one externally would be colour-contrasting doors to make them more easily identifiable by the partially sighted. There would probably also be wheelchair spaces and accessible toilets (possibly a longer windowless area?), the door to be used being marked with a wheelchair symbol.
  7. You're also reverse-biasing the LEDs while the DCC current is flowing the wrong way to illuminate it. This could damage it. You need a normal diode in parallel with each LED, but in the opposite polarity.
  8. On the train, nothing unless you look underneath an are an expert in the different equipment types, or can see the controls in the cab. A steam loco needs some sort of electrical power source for AWS, which could power TPWS too, but on a modern conversion I guess this would be hidden somewhere to avoid upsetting the purists. Not sure about trackside - I guess probably a junction box near the loops themselves and a cabinet near the signal if there isn't one there already.
  9. The crashworthiness risk is indeed more severe, because a tram-train doesn't meet the structural strength standards applicable to trains so would be severely damaged in collision with a freight train. This is addressed by making the collision less likely. The most likely cause of such a collision is Signal Passed At Danger (SPAD) so on tram-train routes extra TPWS is fitted and other adjustments are made so a SPAD can't result in a significant collision. The same principle could be used to reduce collision risks between heritage and commercial services, but as a SPAD by either type of train could be a cause of collision, it would mean having to fit TPWS equipment to the heritage trains as well as to the signals.
  10. A box could be locked out unless controlling a level crossing or any pointwork which needed to be worked to run the commercial service. The railway companies recognized the benefit of being able to do this so many boxes had the facilty, but if one didn't then locking changes would be needed and I think in some cases extra signals (for example if a passing loop was normally uni-directional but operated bi-directionally on one track when the box was closed). A special lever would be pulled to allow clearance of signals that wouldn't normally be allowed (such as in opposite directions on a single line) and a switch would be operated to interlink the block instruments and bells either side so it became one long block section. As to speeds, probably the commercial services would use different locomotives, fitted with AWS/TPWS and otherwise main line certified, so the heritage ones could be labelled as 25mph maximum in the cab. Similarly a driver would know not to exceed 25mph unless they had the necessary extra training to run "commercial". If a "commercial" locomotive and driver was assigned to a "heritage" working then I think the driver could be trusted to stick to the lower speed. There are places on the big railway where certain train types have to observe lower speed restrictions with no signage, just communicated by notes in the Sectional Appendix and relying on the driver's route knowledge to remember this.
  11. Which makes the point that a parcels train couldn't be formed entirely of GUVs and CCTs. There had to be a brake coach with guard's accommodation, and by the 80s once all the more antediluvian pre-nationalization alternatives had been withdrawn it could only be a BG or a passenger brake.
  12. A lot of overnight trains were essentially parcels workings with a seated coach or two tacked on, probably mostly for staff but any passengers for whom the rather random timings suited could use them too. They died out in the 80s probably due to Sectorisation.
  13. The GCR(N) has freight trains running off the main line at Loughborough to the gypsum plant at East Leake, but not while it is running its own passenger trains. The Mid-Norfolk has been storing brand new trains for Greater Anglia until they are ready for use, because the existing fleet occupies all the depot space.
  14. They were only useable from an exchange that was nearby but not the same one as the destination, and I think the code to get the same destination exchange sometimes differed depending where it was dialed from. So they would be pretty useless for advertising. They lasted at least until the late 1980s - I remember if I pressed the first digit too quickly when calling my parents in Newcastle (091) I got a number in Mansfield (91 from Nottingham). My recollection is that most businesses quoted the name of the exchange, or for shop fronts etc just the local part of the number without the area code (xxx xxxx if in a city with a 3-digit area code). In the early days of mobiles a colleague of mine had one which would tell you the area code you were in, so as to be able to call those numbers.
  15. But if you can make a trolleybus that size you can also make a diesel or battery bus the same, less only the marginal extra space needed for engine/batteries which can be above or below and many trolleybuses have that anyway. Trams can be much longer (depending on route issues such as distance between traffic lights) and a bit wider. Hence why a tram is more appropriate at high passenger numbers and has little advantage over engine/battery buses at lower numbers. This is the Translohr. I sampled another route in northern Paris and I think there's a third one somewhere. My impression was it was very cramped and rough riding. A trolleybus might have been better, perhaps with electronic guidance, but an asphalt road carrying identical large vehicles following exactly the same path is prone to rutting so concrete tends to be used for any guided vehicle. A proper high-capacity transport system also need segregated roadspace, probably with physical measures to prevent use by other vehicles, so the ability to change lanes is also less of an advantage than it first appears.
  16. Thanks for this update. So it was moreorless accidental that all numbers beginning with 01 were freed up by the 1990 changes and this allowed us eventually to move to the current system. I'm not sure though how else this problem could have been solved in 1990. I do remember talk of some arrangement for businesses in outer London to get themselves an 071 number to make them look more central.
  17. Another problem with induction charging is that it's not particularly efficient - not a problem for your toothbrush or phone but for a bus or tram it's quite significant. The APS system as in Bordeaux actually has a live rail but it is split electrically into short sections, each of which is energized only when there is a tram sitting on top of it. Trolleybuses occupy a niche between motor buses and trams, but in some ways that niche is getting smaller and may be non-existent in many places. At high passenger numbers they use more energy than a tram, with more obtrusive overhead, and cost more because they are smaller than trams. They also have particulate emission from tyres, increasingly seen as a problem. At low passenger numbers hybrid and battery buses are starting to get the same advantages of performance and no emissions (except tyres) on sensitive parts of the route, without the cost of overhead line. My own belief is that the trolleybus is a technological dead end, except perhaps in very hilly cities.
  18. I think the link mentioned one set of bi-directional cars but they needed to duplicate the equipment that heated the air at each end. Possibly with modern insulation technology there would be better ways to keep the air warm than having to take on hot water or have a small coal fire in the cab. A salt mine in Cheshire has been converted into a large-scale compressed air energy storage, so it's competitive for some applications although obviously very different from a tram.
  19. I think it was exactly that. The intention was to add one digit to all numbers and the easiest way was to free up "01" by changing all London numbers. It had to be done in several stages and there had to be a longish transition between one stage and the next (when both sets of numbers worked) to be reasonably sure that no recipient of a new number would be unduly inconvenienced by it clashing with an old one. They could presumably have kept 0171 and 0181, but then would have had to create other "area codes" for London to cope with the increasing demand for numbers, and these wouldn't have been geographic to any part of London as they would have overlapped with 0171 and 0181. Hence the decision to go to 020 xxxx xxxx for all London landlines. The same process also allowed the creation of 011x codes and adding an extra digit to the local part of the number for several cities outside London that were running out of numbers. Between the start of Subscriber Through Dialling and the 0171/0181 change London enjoyed an advantage. Not did they have one digit fewer in their numbers than anyone else (01 xxx xxxx when Birmingham was 021 xxx xxxx for example, and most smaller places 0xxx xxxxxx). But they also had the "1" code which was the quickest to dial on the old pulse dialers!
  20. Some years ago I was involved in a feasibility study into the use of a heritage railway to run through trains via its Network Rail connections so the towns in served would have a commuter service to the nearby city. We concluded that the only way of doing this without the heritage operation having to take on most of the systems, rules and standards of the national network was to have a "time segregation" where the through trains didn't run at the same time as the heritage service. So at certain times of day the railway would follow national network rules and at others it would revert to heritage rules. For example we though it would need AWS/TPWS but the trackside equipment could perhaps be hidden under wooden planking so as not to be too obvious. Stations could have ticket machines inside an imitation lamp hut or similar, and closed off during heritage running hours. Because on certain weekdays the railway ran a timetable from mid-morning to late afternoon, the commuter service would be limited to not very attractive hours of operation and wouldn't run off-peak or at weekends. I guess heritage trains using main-line certified locos and stock could have allowed both types of service to run at the same time, but the railway wasn't interested in doing this and would probably have had to have the considerable costs involved reimbursed by local government.
  21. At the time these were assigned, phones had two or three letters on the dials next to each number, so 2 would have ABC etc. O or Q was zero. So at least the first two letters of the codes were meant to match with the place name, and I think the codes within areas such as 021 used something similar. From your example Bolton would be BO4, Cambridge would be CA3, Carlisle would be CA8, Derby would be DE2, Doncaster would be DO2. Not sure how this fits with Oxford though!
  22. When the 170s first appeared Roger Ford in Modern Railways did an article on how they were narrower than 158s and mused about whether they had been designed for tilt. However I think he concluded the real reason what that they wanted to have a train that could go anywhere a 158 could go so made them that bit smaller to be sure they would be within gauge. Presumably following that logic, within a few generations trains would become so small that they disappeared entirely...
  23. The railways that can run non-passenger trains above 25mph don't have AWS/TPWS. That would become necessary (along with a whole set of other requirements) only if they ran passenger-carrying trains at the higher speed, or probably if they ran faster non-passenger trains at the same time as passenger-carrying trains so there was a risk of the two colliding.
  24. The 158 was built in a different material (aluminium) from the Mk4 (steel) and designed and built by a different supplier (BREL vs Metro Cammell). You may be thinking of the 156, also built by MetCamm and having a similar bodyshell to the Mk4 but not to a profile suited to tilting. I think also MetCamm were considering buying in the T4 bogie from BREL for the Mk4 but ultimately went for the SIG bogie. The 158 bodyshell had no provision for tilting.
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