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Old May 17th, 2007, 10:05 PM   #1461
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less than efficient service?
Well is it? I've never travelled on it?

Does it stop between the stations constantly?
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Old May 17th, 2007, 10:15 PM   #1462
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http://www.metronetrail.com/default....=1088068912937

According to this, the trains will be fully walk-through like on Hong Kong's MTR... Not like National Rail trains with the doors between the carriages... So i'm still wondering about the potential health risks.

Also, what advantages to articulated carriages bring? And why didn't they implement them on newer stocks?
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Old May 17th, 2007, 10:30 PM   #1463
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No it doesn't. No stops in tunnels, nor delays. Just very very good organization. Timetable fulfillment is 99,94%. I'm using mostly circle line. Intervals between trains are going down to 80 seconds in a peak hour and trains reaches 80kmph in tunnels.

I'm not into all those English terminology. But I suppose conventional signalling means traditional lights in tunnels? I don't think they are cause delays anyhow. I can't even understand how a train located 90 seconds ahead could cause a delay. 90 seconds is pretty long distance. Even if 40-50 sec (between departure and arrive). 40 seconds is still pretty long distance.

Slow passangers and badly organized reverse sidings are main reasons of low tph number.
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Old May 17th, 2007, 10:43 PM   #1464
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Oooh!

If a section of track has a lot of signals can it have more tph than fewer signals? But I assume many operators opt out because it means more costs in maintanence etc.

And yes, you are correct in what is meant as "conventional signalling" the signalling on the Victoria line is ATO... i.e. no signalling!
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Old May 18th, 2007, 05:26 PM   #1465
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How come the tube always has signal failures yet I rarely here of signal failures from other systems?
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Old May 19th, 2007, 01:49 AM   #1466
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Quote:
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No it doesn't. No stops in tunnels, nor delays. Just very very good organization. Timetable fulfillment is 99,94%. I'm using mostly circle line. Intervals between trains are going down to 80 seconds in a peak hour and trains reaches 80kmph in tunnels.

I'm not into all those English terminology. But I suppose conventional signalling means traditional lights in tunnels? I don't think they are cause delays anyhow. I can't even understand how a train located 90 seconds ahead could cause a delay. 90 seconds is pretty long distance. Even if 40-50 sec (between departure and arrive). 40 seconds is still pretty long distance.

Slow passangers and badly organized reverse sidings are main reasons of low tph number.
Provided trains maintain a regular spacing between each other even a 60 second interval is achieveable, but the trouble is that some drivers linger longer in platforms than others or driver slower, so trains start to bunch up. With this sort of frequency even the shortest delay can cause several trains to be held up in consequence.
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Old May 19th, 2007, 01:49 AM   #1467
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How come the tube always has signal failures yet I rarely here of signal failures from other systems?
Old infrastructure
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Old May 19th, 2007, 02:03 AM   #1468
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Provided trains maintain a regular spacing between each other even a 60 second interval is achieveable, but the trouble is that some drivers linger longer in platforms than others or driver slower, so trains start to bunch up. With this sort of frequency even the shortest delay can cause several trains to be held up in consequence.
But nothing is prevent from making a strict time of stops. 10 seconds for example.
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Old May 19th, 2007, 02:18 AM   #1469
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But nothing is prevent from making a strict time of stops. 10 seconds for example.
What do you mean?

Do you mean that if the operators are more strict with dwell times higher tph will be attainable? I don't see how you can just shut doors on crowds of people when they're trying to get home.
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Old May 19th, 2007, 02:19 AM   #1470
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Old infrastructure
But other metros have old infastructure, Paris, New York etc, Yet we don't hear about them having the same kind of problems.
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Old May 19th, 2007, 10:44 AM   #1471
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But nothing is prevent from making a strict time of stops. 10 seconds for example.
Passengers do!

If loading is very heavy 10 seconds might not even be long enough for everyone to alight, let alone anyone to board.

We introduced the SATS system on the Tube (station staff with the white paddles) to try to manage peak dwell times, but I'm unconvinced how effective this has been.

The trouble is, with such a high-frequency / high capacity service, that even a small delay (e.g. a passenger alarm being set off) becomes magnified. The train, even with a 5 minute headway, will lose more and more time as the platforms become busier and busier due to said headway, therefore the dwell time gets longer and longer and the late running worse and worse. If there was a train 90 seconds behind and another 90 seconds behind that, they would very quickly bunch up and you'd have a whole procession of late trains one after the other, with a very busy one in front.
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Old May 19th, 2007, 10:54 AM   #1472
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But other metros have old infastructure, Paris, New York etc, Yet we don't hear about them having the same kind of problems.
I'm certain they do, maybe not as many.

I don't know what systems they have in place, but the reason why signal failures are so damaging in London is becuase of safety systems. A signal failure is a signal remaining at danger when it shouldn't (i.e. no train ahead), so each train must receive individual authority to proceed. The train passes the signal and becomes 'tripped' (i.e. emergency brake application), after the tripcock is re-set it is then limited to 5mph for 3 minutes (= SCAT or 'Speed control after tripping') or until the train has passed 2 consecutive green signals... this means each train stops, contacts the signaller, receives authority, moves forward slightly, stops again, then proceeds at walking pace for several minutes, hence huge delays when the service is timetabled for a train every 2 minutes.

These systems completely remove human error: on Network Rail when a signal fails the driver stops at the signal, speaks to the signaller, who simply states the signal is failing and its ok to proceed at normal speed: much smaller delay, but potentially unsafe due to human error. Perhaps other metro systems are more akin to Network Rail in this respect?

This is why we have had no crashes since 'SCAT' was introduced, but the drawback is the devastating effect of signal failures.
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Old May 19th, 2007, 05:30 PM   #1473
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I have a question tubeman

Sometimes, when the trains pulls away from the platform, there will be a a loud bang (it actually sounds like something breaking), and the train will appear to lose power and slow down. After a second or two, power seems to come back and and the train carries on as normal.

What is this, and why does it happen????

(It certainly happens on the Piccadilly line trains every so often, and i think the Victoria Line trains too....but i can't speak for any other line)
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Old May 19th, 2007, 07:27 PM   #1474
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i asked this before, if memory serves its wheelspin
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Old May 19th, 2007, 09:13 PM   #1475
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Tubeman, why did the designers of the 95/96TS design it so it had two curvers on the walls, rather than one like on the 92TS?
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Old May 20th, 2007, 12:48 AM   #1476
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I have a question tubeman

Sometimes, when the trains pulls away from the platform, there will be a a loud bang (it actually sounds like something breaking), and the train will appear to lose power and slow down. After a second or two, power seems to come back and and the train carries on as normal.

What is this, and why does it happen????

(It certainly happens on the Piccadilly line trains every so often, and i think the Victoria Line trains too....but i can't speak for any other line)
When the driver closes the doors they wait for a 'Doors closed' visual in the cab (often called the 'Pilot Light'), the circuit which proves the doors are all closed must be made for the motors to work. Often, when the train is heavily loaded, passengers may have coats trapped between the doors or simply be pushing against them such that the doors will close and give a 'Doors closed' visual initially, but as the train accelerates the doors are pushed fractionally apart causing the circuit to break and the motors to cut out.

Any time power is cut off to the motors, to prevent drawing an arc, linebreakers are slammed open with air pressure leading to the loud 'pop' noise you hear when this happens. The effect and sound would be exactly the same if the driver wound up to full parallel (i.e. full power to the motors) and shut off manually after a couple of seconds. It feels like the train is decelerating as you as a passenger brace yourself for the rapid acceleration as the train first departs a platform, so when the motors suddenly cut out after a couple of seconds it feels like the train is braking (its not though).

If its a trapped coat of bag strap the acceleration, pop, and loss of power might be repeated again and again until the momentum is such that the acceleration doesn't cause the fractional door opening. You might well hear an exasperated PA announcement from the driver asking for people to stand clear of the doors in this case.

It generally only happens on the older stocks with double-leaf air-worked doors (like the Victoria, Piccadilly, Bakerloo Lines and C Stocks). It happens occasionally on D Stocks and almost never on 92, 95 & 96 stocks.

I remember as a Guard on the Northern Line, when we still ran 1972 Mk1 stocks, that some of the door engines were so dilapidated that even accelerating without anything stuck in the doors could cause this, so the drivers would often accelerate gingerly if they had one of these trains.
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Old May 20th, 2007, 12:52 AM   #1477
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Tubeman, why did the designers of the 95/96TS design it so it had two curvers on the walls, rather than one like on the 92TS?
I don't know, I can only suggest that it might be something to do with tunnel geometry... although it does seem odd in that the 1995 stock on the Northern Line replaced 1959 stock which had the same profile as 1992 stock (i.e. straight sides and a single curve of a roof). Maybe having a more rounded profile makes for a little more space inside the cars?
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Old May 21st, 2007, 05:15 PM   #1478
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Hmm.. do you think the 92TS body shape gives less floor space but more head space?

Anyway, if there are signal failures because of age, then why does the JLE still get signal failures from time to time?
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Old May 21st, 2007, 08:14 PM   #1479
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Hmm.. do you think the 92TS body shape gives less floor space but more head space?

Anyway, if there are signal failures because of age, then why does the JLE still get signal failures from time to time?
If the 92 Stock had less floorspace that would equate to narrower cars... this may be the case. The 95 Stock sit a fair bit higher than the 1959 Stock they replaced (i.e. more of a step up from the platform), so this might be associated with more width.

Re: the JLE, the signalling was a botched job installed hastily when it became apparent ATO wasn't going to happen... This may well explain the failures (which were legendary when the JLE first opened).
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Old May 22nd, 2007, 07:22 PM   #1480
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The JLE is being upgraded to ATO right now, though, and should be using the same system as the DLR in 2009.
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