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Post by simran1966 on Jun 29, 2019 22:31:53 GMT
Hello all,
Perhaps I'd not noticed before but the last few times I've been sitting at the front of a Stratford train at West India Quay, I've seen that the points are set for Westferry and then move to be set for Poplar just before the train departs. However, the previous train went to Poplar too so I'm confused why there needs to be this seemingly redundant move of the points. Any ideas?
Cheers,
Simon.
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Chris M
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Post by Chris M on Jun 29, 2019 23:25:07 GMT
I've noticed this too, my guess is that it is flank protection - a train starting too soon has to travel a lot further towards Westerry before it can potentially come in to conflict with another train than if it were to proceed towards Poplar. Conflicting moves were obviously a lot more common before the diveunder (officially the West India Down Viaduct) was built, but trains can still be routed the old way and the small risk and any cost of change* is probably deemed to outweigh the reduced maintenance costs of moving the points less frequently.
I'm sure I've seen similar behaviour elsewhere in the Canary Wharf area but I can't immediately bring to mind where.
*this could be relatively trivial if it's just a software setting, or very expensive if signalling hardware and safetycases need alteration, I have no idea which it is.
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Post by goldenarrow on Jun 30, 2019 12:49:47 GMT
I agree with Chris M , it must be a legacy from the original delta junction giving a suitable overrun. Route secure indicator displays a horizontal red line before movement authority is given for a Stratford service to move over delta junction to Poplar. Passing without a Secure Route Indication like that would in effect be a SPAD and bring the train to a stop, which wouldn't be completely fail safe with the divergent points to Poplar being so close. I believe a similar example exists at Finchley Central where platform 2 for High Barnay has the route set for Mill Hill East / 25 road until movement authority is given thus protecting the SB road off Mill Hill East even if that protection is only called into use for a handful of services each day. |
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Post by simran1966 on Jun 30, 2019 19:13:57 GMT
Thanks, both. That it's probably a historical thing makes more sense now.
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Post by Deep Level on Jul 2, 2019 5:30:42 GMT
I'm not a points expert and could be completely wrong here so please do tell me if I am but could moving the points regularly also prevent them from seizing and therefore not be able to move them at all? I imagine the maintenance costs involved in moving them regularly would be less than replacing seized points?
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Post by goldenarrow on Jul 2, 2019 13:06:07 GMT
Deep Level , Unlikely as there are several examples of points that stay in a fixed position for most of the days traffic. The regular route for Bank trains from W.India Quay Platform 4 is kept fixed as is the returning route for Canary Wharf terminators via Platform 2. There are also a significant number of emergency crossovers on the DLR that are rarely called into use that would fall into the same category. Chris M , The fact that the rails still shine given that it's been over a decade since W.India Quay lost its regular service from Bank suggests that it is still in use, presumably during the late/early hours. Best chance to travel over it would be during service disruption when there are all manner of rare moves to balance the service.
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Chris M
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Post by Chris M on Jul 2, 2019 13:08:59 GMT
I'm not a points expert and could be completely wrong here so please do tell me if I am but could moving the points regularly also prevent them from seizing and therefore not be able to move them at all? I imagine the maintenance costs involved in moving them regularly would be less than replacing seized points? I can certainly imagine that it will help prevent build-up of snow and ice, but in general terms I wouldn't expect that moving them more frequently than daily would make any difference in terms of likelihood of seizing - I'm not an expert either though. Are there any rusty rail moves from Westferry to West India Quay on the original route? |
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Post by Chris M on Jul 2, 2019 16:16:52 GMT
goldenarrow The DLR do certainly use their flexibility to the max during disruption. The other week there was a failed train at Elverson Road, as part of the working around it they terminated trains from London in Mudchute platform 3, ran a two-train shuttle service between there and Greenwich with one train on each line, and a one-train service bidirectionally on one line between Greenwich and Lewisham.
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Post by superteacher on Jul 2, 2019 17:36:57 GMT
goldenarrow The DLR do certainly use their flexibility to the max during disruption. The other week there was a failed train at Elverson Road, as part of the working around it they terminated trains from London in Mudchute platform 3, ran a two-train shuttle service between there and Greenwich with one train on each line, and a one-train service bidirectionally on one line between Greenwich and Lewisham. Seems ironic that the opposite is being done on the Underground with the removal of useful crossovers and sidings! |
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Post by Tom on Jul 2, 2019 21:40:24 GMT
I'm not a points expert and could be completely wrong here so please do tell me if I am but could moving the points regularly also prevent them from seizing and therefore not be able to move them at all? I imagine the maintenance costs involved in moving them regularly would be less than replacing seized points? I can certainly imagine that it will help prevent build-up of snow and ice, but in general terms I wouldn't expect that moving them more frequently than daily would make any difference in terms of likelihood of seizing - I'm not an expert either though. It shouldn't make any difference, and even if they're not used daily it shouldn't be an issue. |
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Post by brigham on Jul 3, 2019 7:55:48 GMT
Perhaps it's to do with the Clearing Point. If it's on the Westferry route, you might not be permitted to run into West India Quay until the line is clear to that point.
Maybe no-one ever got round to setting a clearing point on the Poplar route?
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Post by phil on Jul 4, 2019 14:26:45 GMT
goldenarrow The DLR do certainly use their flexibility to the max during disruption. The other week there was a failed train at Elverson Road, as part of the working around it they terminated trains from London in Mudchute platform 3, ran a two-train shuttle service between there and Greenwich with one train on each line, and a one-train service bidirectionally on one line between Greenwich and Lewisham. Seems ironic that the opposite is being done on the Underground with the removal of useful crossovers and sidings! To be fair none of the Opperations Chris M described required the use of emergency crossovers (even if it is not used much these days the turnback platform at Mudchute isn’t technically an ‘emergency’ facility. What makes the DLR very flexible is actually the fact that it’s train control system treets all tracks as potentially bi-directional - unlike the traditionally signaled tube / surface railways where bi-directional capability means a massive jump in signalling costs due to all the extra lineside kit required, and in the days of relay based interlockings significantly increased backroom kit too. |
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