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Post by diffusion on Mar 4, 2023 15:00:44 GMT
Looking at Epping station from London direction (webcam) I note that the track to the right doesn’t have the third rail present for quite a distance of track yet the left one does in comparison.
Anyone know why?
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Post by Dstock7080 on Mar 4, 2023 15:12:28 GMT
Are you sure you’re not noticing that the positive rail swaps sides closer to the platform, so that it’s furthest from the platform edge?
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Post by diffusion on Mar 4, 2023 15:21:35 GMT
Are you sure you’re not noticing that the positive rail swaps sides closer to the platform, so that it’s furthest from the platform edge? No it’s not that however it’s just occurred that it’s possibly because it’s where the track splits to allow trains coming from London to crossover on the other track and arrive at the right side platform. ( as you look at the station from London direction) |
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Post by Chris L on Mar 4, 2023 17:56:13 GMT
Are you sure you’re not noticing that the positive rail swaps sides closer to the platform, so that it’s furthest from the platform edge? No it’s not that however it’s just occurred that it’s possibly because it’s where the track splits to allow trains coming from London to crossover on the other track and arrive at the right side platform. ( as you look at the station from London direction) Having travelled to Epping recently I can assure you that the train I was on went into the right hand platform under power. |
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Post by alpinejohn on Mar 5, 2023 14:36:29 GMT
Its to keep 600v supply away from the points mechanism. - Just look at the opening few seconds of this video..
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Tom
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Post by Tom on Mar 5, 2023 15:56:08 GMT
Indeed so; there is a requirement to keep current rails a minimum of 2m away from part of the point operating equipment, which in this case includes a mechanical supplementary drive due to the length of the switches. It's probably more than 2m away because of the length and angle of the diverging route; but to get it any closer would have probably needed a common ramp which isn't a standard component.
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Post by diffusion on Mar 5, 2023 16:03:34 GMT
Indeed so; there is a requirement to keep current rails a minimum of 2m away from part of the point operating equipment, which in this case includes a mechanical supplementary drive due to the length of the switches. It's probably more than 2m away because of the length and angle of the diverging route; but to get it any closer would have probably needed a common ramp which isn't a standard component. Ah, cool. So how does the train move along without that third rail in situ? How are the points controlled after each train pass? |
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Tom
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Post by Tom on Mar 5, 2023 16:26:18 GMT
The car that is over the gap in the third rail isn't motoring and the other cars which are on current are doing all the work.
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Post by stapler on Mar 6, 2023 15:24:27 GMT
Would a 4-car unit get gapped, like at Hainault?
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Post by t697 on Mar 6, 2023 16:19:49 GMT
That's the sort of thing that gets assessed in detail if there's a proposal to run a 4-car train service. Needs the details of gap lengths and locations, together with shoe positions along the train to make the assessment.
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Post by stapler on Mar 6, 2023 17:04:15 GMT
Of course, in the distant past, a 4-car shuttle service did operate north of Loughton.
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Post by t697 on Mar 6, 2023 21:01:44 GMT
And in those days there'd be a set of Gap Jumpers stored there if it was possible to get gapped and crews would know to have sufficient momentum to run through the gap without getting stuck...
I'm not sure whether Central line ATO has 'don't stop' areas where Auto mode won't command a halt and the train would only stop if there was an ATP safety brake application.
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metman
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Post by metman on Mar 6, 2023 21:02:15 GMT
Experienced operators would have coasted over rail gaps that might cause a problem.
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Tom
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Post by Tom on Mar 6, 2023 21:25:44 GMT
That's the sort of thing that gets assessed in detail if there's a proposal to run a 4-car train service. Needs the details of gap lengths and locations, together with shoe positions along the train to make the assessment. Ah, the good old days when people used to do a Gapping Analysis! I'm not sure whether Central line ATO has 'don't stop' areas where Auto mode won't command a halt and the train would only stop if there was an ATP safety brake application. Not quite like that, but we wouldn't position an autostop location somewhere where a train would become gapped (though I think it might have happened once at Hainault where the conductor rail layout changed and nobody considered the consequences for ATO... I'll look tomorrow). |
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Post by t697 on Mar 6, 2023 21:28:38 GMT
Well Gapping Analysis is still done for rolling stock or infrastructure changes. Except when it gets omitted in error or machination!
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