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Post by Deleted on Jan 1, 2006 10:36:27 GMT
Right, first geeky question of the new year......
The curve into and out of the junction at Baker Street has a quite restrictive 15mph speed limit, indicative of a sub 100m curve radius. Does anyone know what the actual minimum curve radius is here? Or is the 15mph speed limit due to reasons other than the curve radius here?
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Post by Deleted on Jan 1, 2006 13:35:29 GMT
On the Northbound the signalling overlaps have a bearing on the allowed speed as a train can be signalled out of platform 1 or 4 whilst a train enters platform 2. On the south/eastbound I would suspect it is just curvature.
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Post by Deleted on Jan 1, 2006 18:41:14 GMT
On the Northbound the signalling overlaps have a bearing on the allowed speed as a train can be signalled out of platform 1 or 4 whilst a train enters platform 2. On the south/eastbound I would suspect it is just curvature. Thanks. I should have made myself clearer in that I'm referring to the junction between the Met and Circle, rather than the crossovers to the N of the Met platforms. |
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Post by citysig on Jan 1, 2006 19:52:01 GMT
Both track and signalling is very tight at both ends.
Can't give you a precise figure for the curve radius, but it's not the tightest on the sub-surface lines by any means.
As for the signalling, the speed restrictions (and numerous speed-control signals) are there mainly to protect the limited overlaps that exist at both the north and south/east ends of the station.
Should a train over-run the platform heading south/east at much more than the restricted speed, and it could end up fouling the junction.
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Post by Deleted on Jan 1, 2006 21:44:35 GMT
Can't give you a precise figure for the curve radius, but it's not the tightest on the sub-surface lines by any means. This begs the question, where are the tightest curves (on main running lines) on the SSLs? |
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Post by stanmorek on Jan 2, 2006 0:43:56 GMT
If memory serves right, the tightest curves on the Circle would be just east of Notting Hill Gate (well north of to be exact) and Kings Cross. Again, no figures at hand but the NHG would be more of a transition curve of varying radius and cant.
Clearance at platform 3 for e/s bound Met would be pretty tight considering end and centre throw of car bodies getting round the curve (not to mention a bigger kinematic profile for higher speeds). Had there been not been a speed limit for the junction there'd probably be some kind of restriction for this. You may have seen the track lubricator located ahead of the curve.
And you may have noticed the high wheel screech as a train goes round there. I remember from 3 years back that P-way were trying different positions and adjustments to the lubricator without solving this problem. I was told that particular section of track had been replaced by a private contractor but there was an ongoing dispute over the handover as the quality of work was poor.
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Post by citysig on Jan 2, 2006 11:48:57 GMT
And you may have noticed the high wheel screech as a train goes round there. I remember from 3 years back that P-way were trying different positions and adjustments to the lubricator without solving this problem. I was told that particular section of track had been replaced by a private contractor but there was an ongoing dispute over the handover as the quality of work was poor. There were a number of excuses given concerning the screech. At around the same time a number of locations also suffered from large amounts of squeel. Some had recent (private contractor) track replacement projects to blame. Some were blamed on trains receiving new wheels. The most believable (and in my opinion honest) excuse I heard though was that the lubricators had not been filled. |
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Post by stanmorek on Jan 4, 2006 2:57:55 GMT
Well I know that there was a dedicated p-way gang maintaining lubricators based at Baker St who were working on the problem (not sure about it now ;D). It was an unusally hot summer and they had found that there wasn't as much grease being deposited on the track as required even though all the lubricators had been set to the maximum levels permitted by standards.
To my knowledge they've since been relocated to West Ken now but the rail/wheel interface issue was all the rage with LU and the infracos back then.
A lot of money was invested and to protect this investment the SSL network was regulary inspected for friction levels.
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