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Old April 17th, 2007, 10:48 PM   #1321
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Quote:
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Arsenal Tube, of course!

Good answer.
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Old April 18th, 2007, 03:23 AM   #1322
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Tubeman, yet another question...

How come on the Jubilee Line Extension theres a strange 'clangy' sound, heres a video to illustrate it: http://www.youtube.com/watch?v=3B-MbVTLZZE

I never hear it anywhere else so i'm just wondering.
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Old April 18th, 2007, 11:29 PM   #1323
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Quote:
Originally Posted by iampuking View Post
Tubeman, yet another question...

How come on the Jubilee Line Extension theres a strange 'clangy' sound, heres a video to illustrate it: http://www.youtube.com/watch?v=3B-MbVTLZZE

I never hear it anywhere else so i'm just wondering.
It's a type of motor / brake system known as 'Chopper', I don't know much about it but the only Tube stock with it is the Jubilee Line. Its something to do with converting DC to AC I think, you hear it during acceleration and deceleration. Some of the Kent Coast networkers operating out of Charing Cross / London Bridge also have the 'Chopper' system and so make the same noises.
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Old April 18th, 2007, 11:43 PM   #1324
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hey tubeman, on my daily commute on the southeasten bexleyheath line there is a strange experience sometimes when leaving a station the train struggles to pull away and sounds like 'chugging' it sounds like a major fault ... what's happening?
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Old April 19th, 2007, 02:47 AM   #1325
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hey tubeman, on my daily commute on the southeasten bexleyheath line there is a strange experience sometimes when leaving a station the train struggles to pull away and sounds like 'chugging' it sounds like a major fault ... what's happening?

Could be wheelspin... Does it happen in the Autumn and / or when its wet?

If there's leaf pulp on the rails or water (in my experience a light coating of drizzle is worse for adhesion than heavy rain) then the wheels will spin as the train attempts to pull away, so it will 'struggle' and make a strange noise as the wheels spin round. Likewise the same conditions impede normal braking: if the brakes are applied too hard the wheels will lock and skate along the slippery rails, which wears flat sections ('flats') on the wheel tread... This gives rise to the rhythmic banging sound you'll hear from many trains as the wheels turn: its bad for the track and bad for the train so 'flats' are generally ground off on a wheel lathe.

A trick I used to use driving the old Northern Line trains, which were terrible for both wheelspin and brakes locking, was to purposefully spin the wheels pulling away to smooth out the 'flats' caused by the previous stop!
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Old April 20th, 2007, 09:44 PM   #1326
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Tubeman, that wasn't exactly the sound I meant nevermind though!

I remember hearing about this terrorist in the news who was planning to detonate a bomb below the thames, thinking it would make the tunnels flood... Would a bomb manage to pierce the tunnel in anyway? Was there any structural damage after the Piccadilly line 7/7 bomb?

Also, why does the Central line still have signal failures even though it has much more update-to-date signalling then other lines?
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Old April 21st, 2007, 02:19 AM   #1327
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Tubeman, that wasn't exactly the sound I meant nevermind though!

I remember hearing about this terrorist in the news who was planning to detonate a bomb below the thames, thinking it would make the tunnels flood... Would a bomb manage to pierce the tunnel in anyway? Was there any structural damage after the Piccadilly line 7/7 bomb?

Also, why does the Central line still have signal failures even though it has much more update-to-date signalling then other lines?
Nah, the 7/7 Piccadilly Line bomb caused no structural damage at all... you have to bear in mind the original Tube tunnels are heavy cast-iron segments bolted together bored through heavy clay, they won't budge an inch. This is why that horrific bomb was so murderous: the explosion was concentrated by the rigid tunnel structure and exploded laterally like a pipebomb through the cars, killing 25 and injuring hundreds. The two Circle Line bombs (Edgware Road and Aldgate) only killed 7 apiece because the explosion was able to expand in all directions due to the larger cars and tunnels, there was some minor cable damage but even then the well-engineered 150 year old brickwork was undamaged.

There are floodgates spread strategically on the underground network installed during WW2 in case a bomb fell into the Thames and pierced the roof of a Tube tunnel, which would have inundated half the network. Thankfully they have never been used in anger, as the idea was that as soon as such an incident occurred they would have been closed, and any train trapped on the wrong side would have been sacrificed to save thousands more lives. As the 7/7 Piccadilly bomb demonstrates, the Tube tunnels are bloody strong and so it would take more than a rucksack bomb to even slightly damage the tunnel.

The Central Line's signal failures aren't like conventional signal failures, they are bugs in the ATO system that causes the trains to 'lose codes', i.e. the ATO signals fail. These glitches are slowly being ironed out: they were terrible immediately after the upgrade.

Sorry I didn't get the right noise... which one did you mean again?
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Old April 22nd, 2007, 01:35 AM   #1328
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Hi Tubeman

Which Tube station has the smallest ground-level floor area? I suspect somewhere like Russell Sq or Belsize Park??

What is the thermal conductivity of the train tracks?


Thanks!
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Old April 22nd, 2007, 02:42 AM   #1329
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Hi Tubeman

Which Tube station has the smallest ground-level floor area? I suspect somewhere like Russell Sq or Belsize Park??

What is the thermal conductivity of the train tracks?


Thanks!
Russell Square is pretty minute... perhaps 30m2?

Aldwych would have definitely taken the prize if it were still open... You pretty much walked stright off the street into the lifts... maybe only 15-20m2?



Regarding thermal conductivity, that's well beyond my knowledge... assumedly the same as any other bit of steel of the same dimensions?
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Old April 23rd, 2007, 04:33 PM   #1330
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Quote:
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Nah, the 7/7 Piccadilly Line bomb caused no structural damage at all... you have to bear in mind the original Tube tunnels are heavy cast-iron segments bolted together bored through heavy clay, they won't budge an inch. This is why that horrific bomb was so murderous: the explosion was concentrated by the rigid tunnel structure and exploded laterally like a pipebomb through the cars, killing 25 and injuring hundreds. The two Circle Line bombs (Edgware Road and Aldgate) only killed 7 apiece because the explosion was able to expand in all directions due to the larger cars and tunnels, there was some minor cable damage but even then the well-engineered 150 year old brickwork was undamaged.

There are floodgates spread strategically on the underground network installed during WW2 in case a bomb fell into the Thames and pierced the roof of a Tube tunnel, which would have inundated half the network. Thankfully they have never been used in anger, as the idea was that as soon as such an incident occurred they would have been closed, and any train trapped on the wrong side would have been sacrificed to save thousands more lives. As the 7/7 Piccadilly bomb demonstrates, the Tube tunnels are bloody strong and so it would take more than a rucksack bomb to even slightly damage the tunnel.

The Central Line's signal failures aren't like conventional signal failures, they are bugs in the ATO system that causes the trains to 'lose codes', i.e. the ATO signals fail. These glitches are slowly being ironed out: they were terrible immediately after the upgrade.

Sorry I didn't get the right noise... which one did you mean again?
Thanks a lot! So useful!

Which line is the fastest? And will the Victoria Line be even faster when it gets new stock?
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Old April 24th, 2007, 01:22 AM   #1331
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Thanks a lot! So useful!

Which line is the fastest? And will the Victoria Line be even faster when it gets new stock?
The Met and Central both have official line speeds of 60mph / 100kmh, although other lines achieve this unofficially and I have heard speeds in excess of 100mph / 160kmh are possible on the Met main, although this is probably bollocks as I don't think the speedos go up that high.

The Victoria Line should benefit from better braking / aceleration with the new stock, so I'm sure on the faster sections (e.g. Seven Sisters to Finsbury Park) 100kmh may well be possible.
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Old April 25th, 2007, 02:57 PM   #1332
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Quote:
Originally Posted by Tubeman View Post
It's a type of motor / brake system known as 'Chopper', I don't know much about it but the only Tube stock with it is the Jubilee Line. Its something to do with converting DC to AC I think, you hear it during acceleration and deceleration. Some of the Kent Coast networkers operating out of Charing Cross / London Bridge also have the 'Chopper' system and so make the same noises.
I read the answer to a similar question in a railway magazine years ago, when a reader was enqiuring about the funny noise from networkers on the Kings Cross line. I can't remember exactly what it said except that the it is Gated Thyristor Operated. It's something like the magnetic poles on the motor are changed as the speed increases/decreases, as a kind of electronic gearing system, in effect altering the physical magnet arrangement in the motors. If what I've written is correct, that should mean the voltages would not need to be varied as the motors step up, avoiding smoothness, efficiency and start-up current surge problems. Is this the same system, or were the 25Kv AC networkers fundementally different from the southern region ones?
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Old April 25th, 2007, 07:21 PM   #1333
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Yes that would make sense, it must be something to do with the acceleration / deceleration process as that's when you hear the sound.

All I know well is older types of Tube stock, and these have 'RPAs' or 'Rotary Pneumatic Accelerators', which in essence are mechanical camshafts which rotate in 10 or so 'notches' as the train accelerates, with each turn making more contacts and supplying more electricity to the Traction Motors. This prevents a sudden surge when the driver 'winds up'.

If you listen carefully on some stocks (in my experience notably 1967 / Victoria, 1972 / Bakerloo and the SSR C Stocks) you can hear the 'tap' sound each time the RPA turns accompanied by a slight lurch in acceleration in the first 10 seconds or so as the train moves off.

Quote:
Originally Posted by elfabyanos View Post
I read the answer to a similar question in a railway magazine years ago, when a reader was enqiuring about the funny noise from networkers on the Kings Cross line. I can't remember exactly what it said except that the it is Gated Thyristor Operated. It's something like the magnetic poles on the motor are changed as the speed increases/decreases, as a kind of electronic gearing system, in effect altering the physical magnet arrangement in the motors. If what I've written is correct, that should mean the voltages would not need to be varied as the motors step up, avoiding smoothness, efficiency and start-up current surge problems. Is this the same system, or were the 25Kv AC networkers fundementally different from the southern region ones?
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Old April 25th, 2007, 10:15 PM   #1334
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Is the Piccadilly line going to be swapped with the District line's Ealing Broadway branch when Heathrow T5 opens? I've just heard about this somewhere and i'm wondering...

And why doesn't the tube have it's own thread when Hong Kong's MTR etc have their own!?!
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Old April 26th, 2007, 12:56 AM   #1335
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Is the Piccadilly line going to be swapped with the District line's Ealing Broadway branch when Heathrow T5 opens? I've just heard about this somewhere and i'm wondering...

And why doesn't the tube have it's own thread when Hong Kong's MTR etc have their own!?!
One of the longer-term plans is to transfer the Uxbridge service to the District Line (who originally built & operated it), but the problem is that after decades of reballasting the track has been raised such that there isn't a comfortable clearance for SSR trains under bridges... They do fit, but are limited to 10mph... In short, it would involve a degree of track lowering under bridges between Ealing Common and Rayners Lane. I think the original deal was for the District to run to Uxbridge and the Piccadilly to Ealing Broadway, but this would still result in three Piccadilly Line branches once T5 opens, so the frequency would be less than ideal.

What I think the optimal solution would be is for there to be complete separation of the District and Piccadilly Lines: the Piccadilly should run to Heathrow only (alternating between T4 loop and T5 trains), and the District should take over the Uxbridge service such that everything beyond Acton Town heading toward Ealing / Uxbridge should be SSR only... therefore platforms can be raised at Ealing Common to prevent the precipitous drop down from District Line trains currently witnessed (as the platforms are served by both SSR and Tube stock), and we'd no longer have Piccadilly trains clogging up the 'slow' platforms at Acton Town delaying the District service.

As the District Line would now have yet another western terminus, I'd run the Uxbridge trains to terminate at High Street Kensington as there are no train paths left through the City... the Uxbridge - High Street trains can fill the slots between Wimbledon / Richmond / Ealing trains vacated by Circle Line trains at Gloucester Road, leading to an 8 minute off-peak service, the same as the Richmond and Ealing services.

As the Olympia service currently terminates at High Street Kensington, I'd truncate it at Earl's Court: Just west of Platform 1 Earl's Court there is a complex of Metronet buildings which could be demolished to create a 3 car length bay platform. The road ex-Olympia continues parallel to the 'main' ex-West Kensington until about 100 yards west of Earl's Court, all that needs to be done is to extend this road to the new bay platform such that a completely self-contained 3-car shuttle service can operate between the new bay platform and Olympia. This would make the Olympia service far more reliable: currently it is not uncommon for a train to depart Olympia on time only to then be held in the tunnel approaching Earl's Court for 5 minutes while late-running 'main' services run past it... It can often take 7-8 minutes just to go the one stop!

So the service patterns would be revised to: (off-peak)

Richmond - Upminster 8 mins
Wimbledon - Upminster 8 mins
Wimbledon - Edgware Road 8 mins
Ealing - Tower Hill 8 mins
Uxbridge - High Street Kensington 8 mins
Olympia - Earl's Court 15 mins (increased to 8 during exhibitions by 'double ending')

There is a 'London Underground' thread buried somewhere, but this seems to be the unofficial LU thread!
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Old April 26th, 2007, 01:50 AM   #1336
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One of the longer-term plans is to transfer the Uxbridge service to the District Line (who originally built & operated it), but the problem is that after decades of reballasting the track has been raised such that there isn't a comfortable clearance for SSR trains under bridges... They do fit, but are limited to 10mph... In short, it would involve a degree of track lowering under bridges between Ealing Common and Rayners Lane. I think the original deal was for the District to run to Uxbridge and the Piccadilly to Ealing Broadway, but this would still result in three Piccadilly Line branches once T5 opens, so the frequency would be less than ideal.

What I think the optimal solution would be is for there to be complete separation of the District and Piccadilly Lines: the Piccadilly should run to Heathrow only (alternating between T4 loop and T5 trains), and the District should take over the Uxbridge service such that everything beyond Acton Town heading toward Ealing / Uxbridge should be SSR only... therefore platforms can be raised at Ealing Common to prevent the precipitous drop down from District Line trains currently witnessed (as the platforms are served by both SSR and Tube stock), and we'd no longer have Piccadilly trains clogging up the 'slow' platforms at Acton Town delaying the District service.

As the District Line would now have yet another western terminus, I'd run the Uxbridge trains to terminate at High Street Kensington as there are no train paths left through the City... the Uxbridge - High Street trains can fill the slots between Wimbledon / Richmond / Ealing trains vacated by Circle Line trains at Gloucester Road, leading to an 8 minute off-peak service, the same as the Richmond and Ealing services.

As the Olympia service currently terminates at High Street Kensington, I'd truncate it at Earl's Court: Just west of Platform 1 Earl's Court there is a complex of Metronet buildings which could be demolished to create a 3 car length bay platform. The road ex-Olympia continues parallel to the 'main' ex-West Kensington until about 100 yards west of Earl's Court, all that needs to be done is to extend this road to the new bay platform such that a completely self-contained 3-car shuttle service can operate between the new bay platform and Olympia. This would make the Olympia service far more reliable: currently it is not uncommon for a train to depart Olympia on time only to then be held in the tunnel approaching Earl's Court for 5 minutes while late-running 'main' services run past it... It can often take 7-8 minutes just to go the one stop!

So the service patterns would be revised to: (off-peak)

Richmond - Upminster 8 mins
Wimbledon - Upminster 8 mins
Wimbledon - Edgware Road 8 mins
Ealing - Tower Hill 8 mins
Uxbridge - High Street Kensington 8 mins
Olympia - Earl's Court 15 mins (increased to 8 during exhibitions by 'double ending')

There is a 'London Underground' thread buried somewhere, but this seems to be the unofficial LU thread!
Gawd you're so helpful!

I would post in the LU thread now that i've found it, but it would be ignored
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Old April 26th, 2007, 02:37 AM   #1337
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Does the Central line have larger tunnels than other lines? Because the trains look/feel more spacious than other deep level tube trains.
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Old April 26th, 2007, 12:54 PM   #1338
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Does the Central line have larger tunnels than other lines? Because the trains look/feel more spacious than other deep level tube trains.
No they are the same, they were originally built to slightly smaller dimensions than the Yerkes standard when they were opened 107 years ago, but were expanded when the Central London railway was absorbed by London Transport. The only explanantion I can offer is that the Central Line cars seem to have straight sides extending higher than most other stock, i.e. the curve of the roof starts higher up, so the cars feel a bit wider. I think the seats are narrower too, giving more floorspace between them. The tunnels are the same size as standard for sure, as the Stock used to be interchangeable (1962 stock displaced by the 1992 stock was transferred to the Northern Line to replace the most dilapidated 1959 stock during the 1990's). Quite a few of the ex-Central Line 1962 stocks I used to drive on the Northern Line still have Central Line route maps in the cabs and 'Central Line' stickers in the windows!
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Old April 27th, 2007, 11:15 AM   #1339
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Tubeman,
The seat coverings in the tube cars are printed with nice colourful graphical motifs. Do you know anything about these designs and if there is a website with all the designs displayed. Thanks!
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Old April 27th, 2007, 04:19 PM   #1340
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Tubeman,
The seat coverings in the tube cars are printed with nice colourful graphical motifs. Do you know anything about these designs and if there is a website with all the designs displayed. Thanks!
They are referred to as 'Moquette' and are a nice feature of Underground trains. They are actually designed to look brighter and cleaner the more worn they are, as the fibres are compacted down the fabric becomes more reflective. You can even buy cushions covered in Moquette from the London Transport Museum!



Classic D Stock Moquette on the left (also used in a lot of buses), the one on the right looks like the Bakerloo line one.

An old 1959 Stock train... towards the end of their life damaged seats were replaced with leftover 1962 stock seats from ex-Central Line trains to cut costs, so there were a lot of 'Frankenstein' trains around with different moquettes inside:



A dog warmer?!?



Lampshades!



Ironing Board cover



New Piccadilly Line moquette



C Stock moquette + pigeon passenger... green, yellow and pink splashes for the District, Circle and Hammermsith & City Lines:



Mostly from here
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