MML Electrification

Discussion in 'Infrastructure & Stations' started by LNW-GW Joint, 7 Jan 2015.

  1. AndyW33

    AndyW33 Member

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    That depends what you mean by electrification. All that is currently under way is Bedford to Corby, with probably Kettering to Market Harborough to follow shortly. This doesn't displace many 222s at all, since St Pancras to Corby is only hourly at the moment. To displace 222s and HSTs in quantity you require either new bi-mode trains (which seems to be what will actually happen) or rapid reinstatement of the plan to electrify Market Harborough-Leicester-Derby-Sheffield and East Midlands Parkway-Nottingham. This part of the programme was cancelled by Grayling.
    At this precise moment, with the new franchise period due to start in a couple of months, there are no orders for new trains, and no plans to electrify beyond Market Harborough.
     
  2. yorkie

    yorkie Administrator Staff Member Administrator

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  3. richieb1971

    richieb1971 Established Member

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    a6.PNG

    Went to see new unit move today and decided through desperation to catch it that I needed to stop somewhere between 2 points that I usually film. So here is the spot I chose adjacent to the A6 dual carriageway north of Bedford where the road and railway have the best clearing of shrubbery. The point of the pic here is a clear illustration of the final look of the OHLE with all wires attached.

    I went to Sharnbrook but no wires were attached and the 4th track progress hasn't moved since my last visit. Please scroll back through the thread to see the latest on that.
     
  4. Flying Phil

    Flying Phil Established Member

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    Thanks for the picture Richieb - you can see why twin track cantilevers need such robust foundations!
     
  5. GRALISTAIR

    GRALISTAIR Established Member

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    Indeed -someday I would love to do the bending moment calculations etc for one of those suckers. Complicated of course by the tension etc in the wires.
     
  6. furnessvale

    furnessvale Established Member

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    There must be a secondary reason for making such large cantilevers from both sides, not quite meeting in the middle. On the face of it, it would appear much cheaper and effective to use a single top beam.
     
  7. richieb1971

    richieb1971 Established Member

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    Apart from the gap, it looks similar to the WCML style of OHLE with the criss cross uprights. Definitely a departure from the ECML and southern MML.
     
  8. InTheEastMids

    InTheEastMids Member

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    Upright steelwork has appeared at the bottom of the embankment behind Wickes to the North of Kettering station. Looks like there will be some fairly burly 4-track portals there.

    More generally I think piling is more or less complete, I estimate ~ 90% of large steelwork is in place. Small steelwork is extensive, and may include some locations where the 4th track is not yet in place.

    Looks like there will be 4 sidings at Kettering each capable of taking, 2*4-car EMUs (ie 160m trains)
     
  9. edwin_m

    edwin_m Veteran Member

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    I'm guessing the reason is that a portal across all four tracks would require all of them to be under possession at the same time. A twin track only needs two of them. Most of the cost is related to possession and site access, so the fact the foundation is that bit bigger and the steelwork that bit heavier doesn't make a lot of difference.

    They even seem to be using TTCs where the pairs of tracks are separated over Sharnbrook/Wymington and effectively double tracks on their own. Traditional practice is to use single track cantilevers both sides on double tracks, and both GWML and the North West electrifications have done this except where there are other factors such as signal sighting. This reinforces my point about site access, as the savings from only doing one foundation must justify all the more visible extra costs of a TTC.
     
  10. hwl

    hwl Established Member

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    Also location of drainage...
     
  11. LeeLivery

    LeeLivery Established Member

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    Out of interest, does anyone know the kind of structures will be erected at Wellingborough & Kettering station considering they're listed? I also read Network Rail are trimming the lovely canopies at Kettering. Is the same happening at Wellingborough?
     
  12. furnessvale

    furnessvale Established Member

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    No doubt you are correct but I question your use of the words "That bit". Both the foundations and the steelwork will be substantially heavier with those cantilevers.

    I also wonder if, in fact they installed those cantilevers using only two lines, leaving the other pair open to traffic. Certainly installing the top member gets quite close to traffic on the other lines, given railway's safety conscious approach to things.
     
  13. edwin_m

    edwin_m Veteran Member

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    That may be so but someone has obviously decided TTCs are the way to go on the MML. If anyone can offer a better suggestion as to why then I'd be interested to hear it.
     
  14. civ-eng-jim

    civ-eng-jim Member

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    Possible basic calculation for straight track. Curved track moderately trickier....

    The tension in the wire will probably support a good bulk of the weight of the wire - I expect a good wooden fence post from B&Q could hold up most OLE! The foundations used could support a small motorway bridge.
     

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  15. 59CosG95

    59CosG95 Established Member

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    The lines are very much paired off by speed rather than direction (e.g. you can keep trains running in both directions on the slow lines wile you install metalwork on the fast lines), akin to the WCML south of Roade, and the GWML east of Didcot. Alongside which, the elevations of both pairs of lines vary, particularly between Bedford & Wellingborough.

    I think it also has a lot to do with the isolation procedures when it comes to adjustments - if you had to move a cantilever at the end of the TTC nearest the 10-foot, for example, you might not need to consider earthing the adjacent lines suspended by the opposing TTC.

    At the end of the day, cost of materials, plant and labour is the big consideration. Bulkier plant (which requires more operatives and costs more to hire) is needed for portals as opposed to TTCs.
     
  16. GRALISTAIR

    GRALISTAIR Established Member

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    Thank you sir!
     
  17. twpsaesneg

    twpsaesneg Member

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    I can assure you that B&Q fence posts don't work...

    Wind loading on the equipment and the structure itself is a major factor, plus you're looking at a catenary tension of 12kN PLUS a contact tension of 15kN for each equipment.

    For the overlap TTC's with 4 equipments on you can be looking at upwards of 200kNm (KiloNewton Metres) overturning moment at foundation levels.

    For simple STC's it comes down a fair amount but it's still significant with an Earth Wire and future ATF (Auto-Transformer Feeder) provision as well.

    Edited to correct ATF abbreviation.
     
    Last edited: 20 Jun 2019
  18. 59CosG95

    59CosG95 Established Member

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    Indeed; the forces on the 4-track Termination Portals (Tensorex IIRC) are probably in the same region of force, hence why they have fairly substantial diagonal struts to mitigate those overturning moments as much as is humanly possible.

    Where the ground is better, and the railway is single or double track, you could get away with using dedicated Simply Supported Anchor (SSA) Masts (typically a 356x368 Universal Column) which don't require backstays, but if the ground is poor and overturning moments are higher, you'd need the big portals.

    UKMS also has two wire tensions; 11kN (catenary)/11kN (contact) for up to 100mph speeds (a la Series 2), and 12kN (catenary)/15kN (contact) for up to 125mph speeds.

    Most piled foundations are 610mm in diameter; the more substantial ones are (I believe) 762mm in diameter and tend to be augered prior to driving the pile (to minimise effects on the surrounding ground - usually the trackbed).

    Also fixed the "ATF" reference for you, although I admit they do go Along Track! You then have Across-Track Feeders to further confuse things :lol::lol:
     
  19. 59CosG95

    59CosG95 Established Member

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    On a separate, disruption-related note, the https://midlandmainlineupgrade.co.uk/ website now shows works going on at each station.
    I recommend paying particular attention to the pages for Bedford, Wellingborough, Kettering & Corby.

    Upcoming works:
    23/6/19: Kettering to Corby replaced by buses all day.
    30/6/19: No early morning trains between Bedford & Kettering. First northbound service from Bedford departs 10:47; first southbound service from Kettering departs 10:45.
    7/7/19: No early morning trains between Bedford & Kettering. First northbound service 10:47. Kettering to Corby replaced by buses all day.
    14/7/19: All trains diverted between Kettering & Syston North Jns (i.e. via Corby & Manton Jn). Leicester & Mkt H'boro served by coach from Kettering.
    21/7/19: Kettering to Corby replaced by buses all day.
    28/7/19: Kettering to Corby replaced by buses all day.
    4/8/19: No early morning trains between Bedford & Kettering. First northbound service from Bedford departs 10:54; first southbound service from Kettering departs 10:50. No trains between Kettering & Corby.
    11/8/19: No early morning trains between Bedford & Kettering. First northbound service from Bedford departs 10:47; first southbound service from Kettering departs 10:50. Kettering to Corby replaced by buses all day.
    31/8/19 to 1/9/19: No service between Bedford & Kettering.
    8/9/19: No service between Bedford & Kettering all day. Kettering to Corby still open.
    29/9/19: No service between Bedford & Kettering all day. Kettering to Corby still open.
    6/10/19: No service between Bedford & Kettering all day. Kettering to Corby still open.
    2/11/19 to 3/11/19: No service between Bedford & Kettering.
    10/11/19: No service between Bedford & Kettering all day. Kettering to Corby still open.
    16/11/19 to 17/11/19: No service between Bedford & Kettering.
    1/12/19: No service between Bedford & Kettering all day.
    21/12/19 to 28/11/19: No service between Bedford & Kettering.
     
  20. hwl

    hwl Established Member

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    610 and 762mm as they are convenient scrap "oil" pipe sizes
     
  21. 59CosG95

    59CosG95 Established Member

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    That's a bit of trivia I had no idea about!
     
  22. quantinghome

    quantinghome Member

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    Also known as 2 feet and 2 1/2 feet.
     
  23. quantinghome

    quantinghome Member

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    Unlikely given motorway cantilever signs (the big football rattle type) usually require a pile group as a foundation, rather than a single pile.

    It's useful to note that the moment capacity of piled foundations increases with the cube of the pile depth, so the pile required for a twin cantilever may only be a little longer than that for a single track cantilever.
     
  24. civ-eng-jim

    civ-eng-jim Member

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    Crikey, I had no idea my comments, obviously said in jest, would be taken so seriously!

    I should have said Wickes fence post....Much better quality (That's also a joke) although wooden OLE poles are not unheard of.

    The catenary and contact wire tensions are predominantly longitudinal to the track (I was not aware STCs and TTCs act as anchor structures). My 5 minute back-of-the-fag-packet calculation was merely demonstrating that the transverse forces required to create the stagger in a contact wire on a straight bit of track is peanuts and that the majority of OLE structures are overly "engineered".

    Again, said in jest - However I don't think I mentioned anything about motorway gantries. On account of their massive surface area they take considerably more wind loading than OLE structures.
     
  25. edwin_m

    edwin_m Veteran Member

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    Not sure if this is another joke but it certainly doesn't make sense - how can a horizontal tension counteract a vertical weight? If one support suddenly broke the ones either side might prevent the wire drooping close to ground level (required for modern street tram OLE but not sure about railway), but those adjacent supports would then have greater load.
     
  26. civ-eng-jim

    civ-eng-jim Member

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    In the sense that a tight horizontal rope held between two points doesn't require intermediate support to prevent it dropping to the floor. It's not levitating, but the wire/cable/rope will sag under its own load, create a small angle to the horizontal and result in a small vertical component to the horizontal force. Attach a weight to the middle of that span, the angle increases and therefore a greater vertical component is generated.

    Hence in my little calculation the 11kN (Or 12kN, 15kN or whatever) force along the wire, only requires a small transverse force to move the wire laterally by 200mm in a 100metre span.

    "A good bulk of the weight" was, it now seems, ambiguous.
     
  27. edwin_m

    edwin_m Veteran Member

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    Indeed so. But the OLE has a catenary wire and droppers which keep the contact wire absolutely straight horizontally (except at vertical curves related to wire gradients) and in fact the supports don't directly support the contact wire, just keep in position horizontally via the register arm. At each support the catenary wire goes off in both directions at a downward angle, so the support is providing a vertical component of the tension in the catenary wire, which in turn is bearing the weight of all the wires half way to the next support in each direction.
     
  28. twpsaesneg

    twpsaesneg Member

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    My point was the radial load you calculated was slightly out, and that if you have 4 equipments supported from a TTC the loads become quite substantial. Both the vertical load and wind load, especially when applied to the nose of the boom are very significant. Whilst the anchor boom structures are indeed very heavily engineered, the TTC structures and others used on MML really aren't overspecified at all bearing in mind the factors that have to be taken into account now due to eurocodes and the more recent NR standards including design life.

    Wooden OLE poles have been proposed and indeed a trial system installed at Carnforth a while back for tramway equipment I believe but they just don't have the design life required and introduce other issues too. Nevertheless they have been seriously proposed in the past - so I wasn't sure it was a joke at all!

    I say this as someone with a vested interest in making electrification better value and more palatable to the government to fund more of. Believe me when I say the engineers are doing the best they can to design correctly and not over engineer for the sake of it.
     
  29. railneighbour

    railneighbour Member

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    Not sure if it's been posted here before, but according to https://midlandmainlineupgrade.co.uk/station/wellingborough/ Platform 4 at Wellingborough is going to be reinstated:

    Kettering also getting longer platform.
     
  30. grumpyoldman01

    grumpyoldman01 Member

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    The Midland Railway used wooden OHL polls on the Lancaster, Morecambe, & Heysham scheme, and apart from those replaced by experimental new designs suitable for 25kv AC electrification between Carlisle Bridge and (I think) Ovangle Road bridge lasted from when the line was electrified in 1908 until it closed in 1966; they looked like telegraph poles, and were capped with small pitched caps.
     

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