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Post by will on Aug 28, 2016 16:11:10 GMT
At about 3 today a signal failure began, exact location not reported that has suspended the Chesham branch for the rest of the day. I was under the impression that there wasn't actually any signals on the branch its self only at Chalfont and Latimer giving access to the branch. If anyone knows the cause or can set me straight on signals on the branch and why it will take all day to fix id be very grateful. Thanks  |
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Post by Harsig on Aug 28, 2016 16:27:55 GMT
Not at work at present, but the most likely scenario is a points failure at Chalfont that prevents the route being set onto or off the branch, and that requires sufficiently extensive repair work such that it cannot be carried out while trains are running to and from Amersham. Presumably in this case a service suspension to Chesham for the rest of the day is considered more desirable than a total service suspension to all destinations for an unknown period while repairs are carried out.
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Post by John Tuthill on Aug 28, 2016 16:31:23 GMT
At about 3 today a signal failure began, exact location not reported that has suspended the Chesham branch for the rest of the day. I was under the impression that there wasn't actually any signals on the branch its self only at Chalfont and Latimer giving access to the branch. If anyone knows the cause or can set me straight on signals on the branch and why it will take all day to fix id be very grateful. Thanks I'm intrigued also. As it's a single line, I would presume that there is something of an electronic 'token' used for safe running? |
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Post by Deleted on Aug 28, 2016 16:55:03 GMT
Axle counters are used to ensure there is only 1 train beyond Chalfont at any given moment
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Post by Deleted on Aug 28, 2016 17:05:00 GMT
Point failure at Chalfont the set that take you into the branch from the main 45 points
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Post by Deleted on Aug 28, 2016 17:08:07 GMT
In the northbound direction, you have the station starter at Chalfont & Latimer, JT80. This is a junction signal, with the main route to Amersham and the diverging route to Chesham. You then have JT83 and its co-acting signal. There are no more signals all the way to Chesham, although there is the unusual A1000 which has only two aspects - yellow and red. As far as I can tell, there is no trainstop and it is merely to warn drivers of the approaching dead-end terminus, but others might know more.
In the southbound direction, there is no station starter at Chesham and no signals will be encountered for about 6 minutes, until you're alongside the mainline. You then encounter JT8 and then JT9, the inner home signal which controls access to the mainline, or the bay platform (now, of course, not used by passenger trains).
There is no token, track circuit block has been used exclusively for many years and has now been replaced by axle counters. Tripcock protection is the sole form of train protection, hence, they say, the provision of JT83 (co-acting).
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Post by philthetube on Aug 28, 2016 18:02:14 GMT
A1000 fails if either the policeman approaching the platform or the one in the platform fail. (policemen are trainstops which regulate train speeds).
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Post by londonstuff on Aug 28, 2016 18:05:21 GMT
In the northbound direction, you have the station starter at Chalfont & Latimer, JT80. This is a junction signal, with the main route to Amersham and the diverging route to Chesham. You then have JT83 and its co-acting signal. There are no more signals all the way to Chesham, although there is the unusual A1000 which has only two aspects - yellow and red. As far as I can tell, there is no trainstop and it is merely to warn drivers of the approaching dead-end terminus, but others might know more. Yes, I often wondered about this. This was before a forum meet years ago I think and the last day of the Chesham shuttle and the bay road. I'm sure I asked about this years ago but never really got a lot of response. (Full album here.)  Final day of the Chesham shuttle by Michael, on Flickr |
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Post by Deleted on Aug 28, 2016 18:39:36 GMT
There should be a trainstop as its the end of the line so you would of thought there would be atleast 1 speed control trainstop going in. Never been or worked up there so wouldn't like to say 100%
Oh btw the fault today was down to a faulty circuit controller which they have decided to leave until tonight. Would only take about 20mins to change
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Post by Deleted on Aug 28, 2016 19:07:15 GMT
There should be a trainstop as its the end of the line so you would of thought there would be atleast 1 speed control trainstop going in. Never been or worked up there so wouldn't like to say 100% Oh btw the fault today was down to a faulty circuit controller which they have decided to leave until tonight. Would only take about 20mins to change As far as I know, there are two blind TETS trainstops, one at the entrance to the platform, one about halfway down, and obviously the fixed one at the end. But A1000 signal doesn't seem to have an associated trainstop. Anyway, here's a diagram for general interest, with number 45 points circled, although were they not the issue after all?  |
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Post by will on Aug 28, 2016 19:37:09 GMT
Thanks everyone couldn't have asked for better information |
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Post by seaeagle on Aug 28, 2016 20:00:23 GMT
Correct me if I'm wrong, from my days on the Met I was told that A1000 is the only automatic signal on the system without a trainstop.
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Post by Deleted on Aug 28, 2016 21:41:02 GMT
It did have a trainstop at one time - from my notes:
23/1/76 - 2 fixed red lights and fixed trainstop at Chesham ('Moorgate' signalling). Signal A1000 at 4-car stopping mark and 4½ second time release at signal A1000 for 8-car trains.
21/2/88 - 15mph approach controlled trainstop moved 41m south at Chesham. Signal A1000 removed but trainstop retained (but moved 10.3m south) and 10mph approach controlled. New fixed trainstop and two fixed red lights at north end of platform (where all trains to stop) and new track circuit interrupter commissioned. (Traffic Circular 6/88)
and for 21/5/94 - Axle counter installed on Chesham branch and fixed distant signal becomes new A1000 south of station for northbound trains. Signals decommissioned:
JT69A – Chesham starter
JT69B – Chesham running
JT69B – Co-acting for Chesham running
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metman
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Post by metman on Aug 29, 2016 4:34:02 GMT
What is the line speed on the chesham branch? 40mph?
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Post by Deleted on Aug 29, 2016 5:13:48 GMT
What is the line speed on the chesham branch? 40mph? 35, I believe. |
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Post by crusty54 on Aug 29, 2016 5:40:02 GMT
looks like it wasn't a 2 minute fix.
Still closed this morning according to the BBC.
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Post by will on Aug 29, 2016 6:49:55 GMT
looks like it wasn't a 2 minute fix. Still closed this morning according to the BBC. A taxi service is replacing trains between Chesham and Amersham and they have said it's a signal failure at Chalfont. |
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Post by Dstock7080 on Aug 29, 2016 7:11:28 GMT
What is the line speed on the chesham branch? 40mph? 35, I believe. 15mph over points at Chalfont, then 35mph on branch. looks like it wasn't a 2 minute fix. Still closed this morning according to the BBC. A taxi service is replacing trains between Chesham and Amersham and they have said it's a signal failure at Chalfont. A point motor control unit is required at Chalfont and unfortunately an engineer wasn't available overnight. Taxi to remain in place for today. |
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rincew1nd
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Post by rincew1nd on Aug 29, 2016 7:16:42 GMT
Bring back the shuttle, wouldn't have been a problem then!
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Post by Deleted on Aug 29, 2016 7:30:03 GMT
It's a circuit controller which has failed an engineer was on site last night but couldn't get it to work properly so they will be back again tonight
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Post by countryman on Aug 29, 2016 8:08:25 GMT
Bring back the shuttle, wouldn't have been a problem then! What would you use for this? I'm assuming the bay is too short for an S8 or S7. |
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Post by Chris M on Aug 29, 2016 9:46:26 GMT
The bay being too short for S stocks is the reason why the shuttle service was withdrawn.
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Post by Deleted on Aug 29, 2016 10:04:11 GMT
It would fit a 3 car D stock
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Post by Deleted on Aug 29, 2016 11:17:21 GMT
Service resumed after defective part replaced
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Post by philthetube on Aug 29, 2016 12:06:20 GMT
It could be possible to have made it possible to lock in an S8 on the branch using the Selective door opening to only open doors on half the train at Chalfont, however it would be unconventional, probably difficult to get past regulators and not worth the trouble for the very rare occasions needed.
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Post by knap on Aug 29, 2016 12:29:02 GMT
Currently on a train to Chesham (13:25). Auto line announcements at stations advise no service to Chesham. Auto announcements on train says all stations to Chesham and then says there is no service to Chesham! Web site says good service on Met with previous details of no Chesham service removed. Confusing information being provided by TFL.
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Post by phoenixcronin on Aug 29, 2016 15:57:30 GMT
Currently on a train to Chesham (13:25). Auto line announcements at stations advise no service to Chesham. Auto announcements on train says all stations to Chesham and then says there is no service to Chesham! Web site says good service on Met with previous details of no Chesham service removed. Confusing information being provided by TFL. I heard via the train radio that there's no one available to edit the S Stock DVA. The guy has apparently gone home |
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Post by will on Aug 29, 2016 21:17:37 GMT
Currently on a train to Chesham (13:25). Auto line announcements at stations advise no service to Chesham. Auto announcements on train says all stations to Chesham and then says there is no service to Chesham! Web site says good service on Met with previous details of no Chesham service removed. Confusing information being provided by TFL. I heard via the train radio that there's no one available to edit the S Stock DVA. The guy has apparently gone home That is some seriously bad planning that TFL won't have the ability to edit the DVA on 192 trains if one guy goes home. Imagine if he suddenly left and there wasn't anyone who has the knowledge to do the job. They really need to have a system that monitors who has what skills and knowledge to ensure it's retained within the company. |
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Post by phoenixcronin on Aug 29, 2016 21:53:53 GMT
I heard via the train radio that there's no one available to edit the S Stock DVA. The guy has apparently gone home That is some seriously bad planning that TFL won't have the ability to edit the DVA on 192 trains if one guy goes home. Imagine if he suddenly left and there wasn't anyone who has the knowledge to do the job. They really need to have a system that monitors who has what skills and knowledge to ensure it's retained within the company. "The guy has gone home" may have been an off the cuff remark, but I agree that having trains running around for hours announcing wrong information is very sloppy |
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Post by Red Dragon on Aug 30, 2016 11:07:01 GMT
I heard via the train radio that there's no one available to edit the S Stock DVA. The guy has apparently gone home That is some seriously bad planning that TFL won't have the ability to edit the DVA on 192 trains if one guy goes home. Imagine if he suddenly left and there wasn't anyone who has the knowledge to do the job. They really need to have a system that monitors who has what skills and knowledge to ensure it's retained within the company. Is the system for the DVA on the 09 stock similar? Surely they could both be done by the same person? And maybe when/if the NTfL with its real-time information screens that won't actually work is introduced, they could also be programmed by the same person. |
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