Bus & Tram controlled traffic lights

Discussion in 'Other Public Transport' started by sleepy_hollow, 15 Mar 2019.

  1. sleepy_hollow

    sleepy_hollow Member

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    I would welcome references to bus or tram controlled traffic lights, both system (1) and equipment level, particularly manufacturer's data or official descriptions of systems, although histories would also be useful (2).

    I am thinking of things like refs (1) and (2) but for as many examples as possible, both in the UK and abroad.

    It is my understanding that trams have always controlled road signals, but that buses doing so is a newer development. Also I believe that trams often, but not always, have absolute priority in setting signals for the tram route. I suspect UK practice tends to regard a tram route as something that should take its turn with other traffic, as bus routes generally do.



    (1) Selective vehicle detection in London – official TFL leaflet http://www.tfl.gov.uk/assets/downloads/businessandpartners/svd-brochure-2006.pdf

    (2) Bus & tram priority in Sheffield – unofficial description
    http://busmeister.wikispaces.com/intro_TSP
     
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  3. kilonewton

    kilonewton Member

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  4. rebmcr

    rebmcr Established Member

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    I know that when the T68s were introduced in Manchester, detection was by two induction loops buried between the rails, set distances from the stop position. On smaller junctions they had absolute priority, but in some of the more important locations (e.g. Princess Street) they only had relative priority within the usual cycle.
     
  5. sleepy_hollow

    sleepy_hollow Member

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    Thanks for both comments.

    The Melbourne paper definitely describes what I was thinking about, although as far from the UK as you can get. I assume that it is not necessary to go to the antipodes to find this sort of thing although an academic paper being dated 2018 does suggest that the idea still has some novelty. Interesting that it is based on conventional induction loop technology.

    Equally interesting that tram control of road traffic signals in Manchester dates only from 1992, I had thought trams had controlled signals from the beginning of electric tramways, but I suppose traction motor current control of points came in before traffic lights.

    As you might expect the Manchester Metrolink website provides little technical information.
     
  6. rebmcr

    rebmcr Established Member

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    I can't speak to that — it may well have existed also on the previous tram system, but that pre-dates me!

    I seem to recall the information I posted originally came from a book in my local library (I am just old enough to remember life before the mainstream internet!) — unfortunately I can't give any real clues to its identity. It was a paperback, A4-ish in size, glossy with perhaps 100 pages, monochrome photos throughout, and a grey/turquiose cover to match the Metrolink corporate identity of the time. Content covered construction, and the network's operation as it was initially. Publication can't have been later than 1996.
     
  7. Ken H

    Ken H Established Member

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    the old tram systems relied on a bloke standing in the street working points. and early traffic lights had a man pushing buttons on a cabinet to do the phases. before solid state electronics, automating logic relied on lots of relays.
     
  8. Deerfold

    Deerfold Established Member

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    Have TfL removed that since you posted the link?

    I used to work on the AVL system in London - we too used radio beacons around London - we had to tell the AVL system about the SVD beacons which worked in much the same way as ours except ours were battery powered and theirs were wired into the mains.
     
  9. Adlington

    Adlington Member

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    Something like this, from Flandres?
    Incorrect.
     
  10. Man of Kent

    Man of Kent Member

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    Possibly this book: https://www.abebooks.co.uk/9781872524368/Light-Rail-Systems-Manchester-Metrolink-1872524362/plp
     
  11. edwin_m

    edwin_m Veteran Member

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    Most junctions on most modern UK tramways have some form of tram priority. I was told that the only one that didn't in Nottingham was Parliament Street, but that was before the extensions so there may be others or there may even be priority there now.

    However priority is not absolute. In particular, if a tram passes in one direction there has to be a minimum green phase for conflicting road traffic, and if a tram arrives in the other direction during this time it will have to wait.

    The principles are in this publication, particularly Appendix B: https://webarchive.nationalarchives.../assets/pdf_file/0018/2637/rspg-2g-trmwys.pdf
    This document is contemporary with the original "modern" British tramways and more recent systems may use GPS instead of fixed detectors. I can't speak for bus priority, but I guess the GPS-based systems would work for that too.
     
    Last edited: 18 Mar 2019
  12. rebmcr

    rebmcr Established Member

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  13. glbotu

    glbotu Member

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    Despite the long paper about 'modern' priority techniques in Melbourne some of the tram routes still switch points with a stick. The driver gets out (with their stick) and switches the points. You can see this at the junction of Balaclava Road and Hawthorn Road.
     
  14. Jan

    Jan Member

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    While traffic lights starting becoming more common even before World War II, their numbers only really took off (especially from a European perspective) after the war as automobile road traffic increased significantly. At the same time, trams were seen as an outmoded form of transport in lots of cities and loads of tram systems consequently were closed down, so my guess is that there would have been little desire to implement any more advanced forms of traffic light controls for trams even using the technology of the day. There must have been some pioneering installations somewhere, but no large-scale installations I guess. Electric point control on the other hand arrived during, respectively even before the heyday of trams and consequently would have seen much more widespread usage.

    Besides, the logic for traffic-actuated signals and/or tram priority can get relatively complex pretty quickly, so before the large-scale advent of cheap and miniaturised electronics, fixed-phase traffic lights were much more common as the simpler and cheaper to implement option, even in cities that did keep their trams.

    Specifically regarding your question, I have a few scanned articles, but they're in German and as I didn't get around OCRing them so far, you can't simply paste them into an online translator, either, so I'm not sure how much use they'd be to you. One describes a pioneering (for Karlsruhe) installation of traffic-actuated signals implemented in relay logic in the mid-/late 70s (Edit: see below for correction), which included tram priority for the tram line running in parallel to that road, while the others deal with the large-scale implementation of tram priority in the city which only happened in the late 80s/early 90s (and a few intersections struggled on into the 2000s). Let me know if you're still interested.
     
    Last edited: 20 Mar 2019
  15. kilonewton

    kilonewton Member

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    I think that might be somewhat unfair. The intersection you refer to is possibly the only full 4 way tram intersection in Melbourne, and has plenty of moves to and from Glenhuntly depot through it.
    In my experience of travelling on the network (20+ years ago to be fair) the Drivers only got out with the “stick” to change the points if they were following another tram on a divergent route and to switch the dial on the console to their route would mean the tram in front possibly going the wrong way. The sensors were on the overhead line some way short of the intersection, however a quick Google Streetview look at the intersections I travelled through regularly shows that equipment has been removed. That said, my last trip earlier this year I didn’t notice the drivers of the 58 (still the 55 to me!) having to get out to use the stick.
     
  16. Belperpete

    Belperpete Member

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    I can recall going on an IRSE visit to traffic control in New Scotland Yard sometime in the late 70s or early 80s. At that time, most of London's traffic lights worked on fixed sequences, with different timings depending on the time and day, controlled by a 7 day timer in the local control cabinet Any change, such as for roadworks or a special event, required the police to take local control (it was not uncommon to see policemen operating traffic lights manually in those days - can't recall ever seeing it nowadays), or for a technician to be sent to site to reprogramme the control box. They were in process of implementing a system where, for the more important junctions, they could override the switching between the different preset phases from the traffic control office. However, they could only switch between sequences that were already installed in the local cubicle, and in those days, the switching required a GPO line laid to each control cubicle. I understand that it was only once the lights became processor controlled, was it possible to download new sequences, rather than just switch between existing sequences.

    Many traffic light controllers can give priority for emergency vehicles. I think this was initially done by a control from the central traffic control office, but I understand in some cases this can now be triggered direct from the vehicles themselves.

    Many tram priority controls use similar vehicle detection equipment as used to detect road vehicles - obviously this only works where the trams are in a segregated lane approaching the junction. However, this allows standard traffic light controllers to be used, without any special (and considerably more costly) interfaces.

    I have been involved in a few level-crossing schemes where there is an interface between conventional road traffic lights and the level crossing. The usual method was to send a control from the level crossing that made the traffic lights speed-up their sequencing to get to the required phase (often called a "hurry-up" control). The level crossing initiation would be delayed until the traffic lights got to the correct phase, or a suitable time had elapsed.
     
  17. edwin_m

    edwin_m Veteran Member

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    For a fun couple of hours go and stand at David Lane in Nottingham. Road, railway and tramway alongside each other with another road crossing all three. If a tram approaches the lights go red for the crossing road but the barriers stay up. If a train approaches the lights go red much earlier and the barriers come down.
     
  18. sleepy_hollow

    sleepy_hollow Member

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    Thank you all for the further references, I have some reading to do. Also for the reminder that information can be found in paper books; I shall shortly apply myself to the local library catalogue, although technical detail at this level, like actual timetables, tends to be below the level covered by the type of book stocked by public libraries.

    Thank's also for the various corrections about traffic and tram signal history. I had forgotten that both came in before automatic control, although the suggestion that tram controlled switching goes back a long way does match my earlier understanding.

    I can read, or at least decipher, German, so those scanned papers could be of interest.


    I think I checked the TFL reference shortly before posting, but it does now seem to be absent. Siemens, the supplier used, do appear to have selective vehicle detection (SVD) material on their website. I have attached my pdf copy of the paper I referenced.
     

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  19. Jan

    Jan Member

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    Dug up that article again and I've actually misremembered things slightly: The 1978 installation already employed microprocessors, and was mainly about installing a "green wave" for the parallel road while maintaining priority for the parallel tram line. The tram line itself already had priority at the signalised intersections since it was converted from a former narrow gauge railway in the late 50s, but it was very much a special case precisely because it was a former railway (actually legally it still is a railway to this date, even if de facto that section within Karlsruhe is operated very much like a tram line with running on line-of-sight, tram-style signals at intersections instead of full-blown level crossings etc.). The rest of the tram network was very much plagued with long waiting times at mostly fixed-cycle traffic lights until the 80s.
     
    Last edited: 22 Mar 2019
  20. edwin_m

    edwin_m Veteran Member

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    That would be the Albtalbahn, arguably the grandfather of the Karlsruhe tram-train model. It's a bit more railway-like when it gets out into the Black Forest, and may even still run steam trains occasionally.
     
  21. Belperpete

    Belperpete Member

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    If you know the details of a particular book, even if your local-authority central-library doesn't stock it, your local library should be able to obtain it through the national inter-library lending service.
     
  22. Belperpete

    Belperpete Member

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    As I recall there are two crossings where NET and the Robin Hood line run parallel. At one, the tram runs inside the barriers together with the NR line. At the other (David Lane), the tram runs outside the barriers.
     
  23. sprunt

    sprunt Member

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    Eindhoven has bus controlled lights - in the Strijp district they operate like level crossings, with bells ringing as the buses approach (and I want to say barriers dropping, but I can see no sign of that on Google Streetview so perhaps it's a false memory). I did wonder if that was maybe a nod to the former industrial nature of the area.
     
  24. randyrippley

    randyrippley Established Member

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    The Manx Electric Railway could be worth checking, they've had tram controlled crossing lights for a long time
     
  25. Belperpete

    Belperpete Member

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    Where? They have level crossings with flashing red lights, but I am struggling to think of anywhere the electric trams are integrated with standard road traffic lights.

    The horse tram on Douglas promenade, where it passed through the traffic-light controlled junction near the Villa Marina, used to have special traffic signals that consisted of big red and green lights with a horse symbol. Think of the red and green man for pedestrians, but with a horse symbol, and about twice the size.
     
  26. randyrippley

    randyrippley Established Member

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    As far as I can remember there were at least three.........one set in Ramsey, one set where the line crosses the road at Laxey, one set south of Baldrine where the line crosses the A2, but looking at Google maps shows all three are now level crossings
     

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