kabsonline
Best SSL Train: S Stock Best Tube Train: 92 Stock
Posts: 686
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Post by kabsonline on Jan 20, 2013 22:16:08 GMT
Hi all Just got a call from my uncle who lives near the Met at Chalfont. Apparently a London bound train has got stuck just before the station and passengers are being walked up the track to the platform. Website states the line is suspended between Rickmansworth and Chesham/Amersham because of adverse weather conditions. Update: Train is now being moved back towards Amersham. Anyone know what exactly happened? kabsonline  |
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Post by memorex on Jan 21, 2013 12:31:30 GMT
I was working at Harrow, so don't know the full details, other than that two trains were stalled with no movement in the Chalfont area.
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Post by knap on Jan 21, 2013 12:38:15 GMT
It did not seem to be much better this morning. At 7:20 there was an S stock stuck in platform 1 at Amersham and there were announcements at Chalfont saying a train was stuck at Chesham. Thus not Met service fir quite some time. Luckily the line was clear and Chiltern could run trains but they did not appear to make any extra stops to pick up Met passengers, but some of their services may have been too long to allow a stock at Ricky
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Deleted
Deleted Member
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Post by Deleted on Jan 21, 2013 13:10:11 GMT
How does the S Stock compare to the A Stock in icy conditions? I ask this as in the past the National Rail Network has had issues with new EMU's with 3-phase drives being over sensitive to transients due to arcing.
There was a famous incident in the early 1990's near Birmingham where 3 Class 323's got stuck as one went recuse the other and their systems shut one by one due to arcing issues!
XF
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Ben
fotopic... whats that?
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Post by Ben on Jan 21, 2013 14:53:05 GMT
Saw a friends Facebook status saying (a few hours back) that they had been waiting at Northwood for a train for 50 mins, and would have another 15 till it came.
So much for 8tph... :**
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Ben
fotopic... whats that?
Posts: 4,282
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Post by Ben on Jan 21, 2013 14:56:40 GMT
XF:
Yes that seems to be a common story with modern traction packages. Didn't the Networkers suffer a similar fate to start with?
Maybe as super capacitors are developed further it'll become possible to smooth the supply voltage onboard further to reduce spikes and troughs resultant of arcing and other contact problems?
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Deleted
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Post by Deleted on Mar 4, 2013 16:15:14 GMT
My experience driving Sstock in the snow is that they are pretty good, others may tell differently. If a 3/4 rail train cannot get juice because of snow/ice it will not go anywhere regardless of traction package.
I would have thought it would have been a good idea to design Sstock to allow retro fitting of pantographs to be used instead 4th rail should Chiltern decide to electrify. Most modern stocks are built with duel voltage capability so why not these.
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metman
Global Moderator
5056 05/12/1961-23/04/2012 RIP
Posts: 7,421
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Post by metman on Mar 4, 2013 20:42:57 GMT
I would imagine because the cost and the fact that the lines the S stock run on have virtually no chance of being converted to OHLE.
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Ben
fotopic... whats that?
Posts: 4,282
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Post by Ben on Mar 4, 2013 23:22:56 GMT
I believe it was commented on another thread that fitting a panto was considered for the S stock but rejected for structural reasons...
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Post by christopher125 on Mar 6, 2013 0:07:04 GMT
I would have thought it would have been a good idea to design Sstock to allow retro fitting of pantographs to be used instead 4th rail should Chiltern decide to electrify. Most modern stocks are built with duel voltage capability so why not these. It's hard to see the relatively sparse Chiltern service justifying a conversion of LU lines to OHLE, especially if the rest of LU won't be converted. Should the Chiltern services be electrified then the relevant Met lines can presumably adopt the same approach as the shared sections of the Wimbledon and Richmond branches, with Chiltern using conventional Dual Voltage units. Chris |
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Deleted
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Post by Deleted on Mar 27, 2013 18:32:19 GMT
Hello,
As far as I remember, Boston blue line (the one going to Logan airport), uses both systems: third rail roughly from city centre to the airport (due to gauge concerns in a submarine tunnel), overhead line further on. But both types of feeder bring the same current ( 650 V DC AFAIR).
Using Chiltern OHL and necessarily 25 kV AC would imply to add in every unit a transformer and a rectifier. The latter can be avoided if the unit uses thyristors to "axe" (sorry, don't know the English word!) the current, but the former still needs to be added, which is costly, heavy and takes a lot of space...
Anyway, OHL are not always better than third (and fourth) rail. We have recently had a branch of the A line in Paris totally closed until the mid-afternoon due to frost sticking to the wires.
Not sure there is a universal solution!
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