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posted: 12 Feb 2017 22:36 from: FraserSmith
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I was looking through Wikipedia for pictures of timbering at wide track formations and spotted this photo by Signalhead under CC BY-SA 3.0 in the Switched Diamond section. I have a couple of similar situations and I was unsure as to how the timbering would be dealt with but having seen this I think I might use this method. 3137_121655_330000000.png Is it common for the timbers to be arranged like this with alternate timbers having joints in the 4ft of the crossing tracks? It's not clear whether the last few timbers towards the concrete sleepers are similarly joined. Between the right hand tracks on the three before the concrete it appears that the sleepers might be shorter but it's difficult to tell with the ballast as it is. The left hand side is similarly vague. Since when would this arrangement have been used in such junctions? Thanks in anticipation Fraser |
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posted: 12 Feb 2017 23:50 from: Tony W
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Hi Fraser. Yes, this would be a typical method of timbering such a situation avoiding overly long timbers in the process. Having gaps in the timbers in alternate 4ft ways is very common and you will find examples where two successive timbers have gaps in them although this does tend to weaken the formation slightly. Bullhead track was timbered similarly for many years. Looking at the picture, I agree with you that the last three sleepers on the right before the concrete sleepers are separate but think that it is the timbers under the Diamond that are short. I would be very surprised if the last three sleepers before the concrete ones are as short as they appear, as they would not provide adequate support, but stranger things have happened when needs must. Regards Tony W. |
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posted: 13 Feb 2017 17:00 from: Martin Wynne
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Hi Fraser, Crossing timbers were (are still?) generally stocked in 6in. increments up to 15ft length (for turnouts) and in 19ft-6in or 20ft length for crossovers in ordinary double-track. Longer lengths could be specially ordered by the designer up to 30ft, but they are expensive and difficult to handle, so avoided if possible. Where it is necessary to place 2 timbers end to end you have a choice. Sometimes timbers were halved and spliced together to create a very long timber, using old fishplates bolted through the joint as stiffeners. This makes an interesting seldom-modelled feature. The disadvantage is that it is a lot of on-site work to do, and the creosote protection is largely destroyed in the process, leading to early rotting. Alternatively you can simply leave a gap between them, provided there are adjacent timbers holding the rails to gauge. This means the gaps would be typically alternated in adjacent roads, and ideally placed in the least heavily-traffic roads. Note that if you leave a gap it needs to be a definite gap, not with the timber ends butted close together. This is so that if the timber needs packing, the gang can dig out all round it to insert jacks, etc. You can see it in your picture: 2_131152_340000000.jpg But note that there are no hard and fast rules about any of this. Each timbering layout is designed for the actual site using the practice of the local design office. If we lay down any rules here, someone will come along and post a photo showing the exact opposite. regards, Martin. |
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posted: 13 Feb 2017 20:58 from: Jim Guthrie
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The Americans were doing similar - like this crossover for the Union Pacific Railroad. Scroll down to the fourth page http://www.up.com/cs/groups/public/@uprr/@customers/@industrialdevelopment/@operationsspecs/@specifications/documents/up_pdf_nativedocs/pdf_up_std_5000.pdf Jim. |
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posted: 14 Feb 2017 18:21 from: DM
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I once found a crossover newly re-timbered with every timber jointed in the 4' of the cross-over road. Must have made the TME's day when I rang him up to tell him about it. | ||
posted: 15 Feb 2017 12:10 from: Tony W
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You can't get the staff! Tony. |
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