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Post by ikar on Sept 15, 2005 16:01:37 GMT
When the Heathrow T4 station closes do the trains continuate to do the loops or just terminate at Heathrow T123
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Deleted
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Post by Deleted on Sept 15, 2005 16:27:46 GMT
Originally the Piccadilly only ran to Terminal 1,2,3 (known as Heathrow Central at the time) before the loop was created for Terminal 4, so there is double tracking to the 1,2,3 station. The westbound track to the station has been brought back from the dead and is now being used by passenger services.
The loop itself is closed so that engineers could create the tunnels leading off to Terminal 5 I believe, although how the tunnels will connect with the current ones is beyond my knowledge.
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Post by Deleted on Sept 15, 2005 17:31:33 GMT
*deep breath*
The works at Heathrow Terminal 5 for the Piccadilly Line involve the construction of a standard island-platform twin-track terminus, with a scissors crossover beyond the platform headwall and two reversing sidings beyond that. This layout allows trains to proceed into the w/b terminating platform, detrain their passengers, then run forward into either siding, allowing the driver to change ends and return to the e/b starting platform.
Before the works were started, the single track Piccadilly loop split into two tunnels at an underground junction and connected end-on with the overrun tunnels at Heathrow T123, once known as Heathrow Central. Now, the intent is to change that end-on junction into a flying junction - the single-track tunnel from Heathrow T4 will pass underneath the w/b tunnel from Heathrow T123 and form a trailing junction with the e/b tunnel from Heathrow T5. Thus, in this manner, part of the original T4 service will be retained. This junction is called PiccEx Junction.
Heathrow T123 itself will not change dramatically; its scissors crossover may see simplification or removal, but the only difference to passengers will be that it is no longer a terminus station; it will become a through station to Heathrow T5 and a through station from Heathrow T5 and Heathrow T4.
Hatton Cross will not change either; the only difference may be the provision of an LED DMI to allow passengers to switch trains if they got on a T4 looper instead of a T5 reverser.
Passengers to and from T4 will also get a slightly better service; because of the changes at PiccEx Junction, trains will now "wait time" here in order to fulfill their timetable obligations. This means that trains can "fill up" in a manner similar to a terminal station, and means that T4 passengers will have less of a chance of missing a train.
The only caveat to the construction of PiccEx Junction is that the T4 connection faces the wrong way, as far as I know; this means that while T123 will get a full (yet uneven) service of Piccadilly trains, T5 will only get a 3/4 service of Piccadilly trains, while T4 will get only 1/4 of Piccadilly trains sent to the airport.
*gasp*
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Phil
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Post by Phil on Sept 15, 2005 18:22:35 GMT
No chance of a diagram to supplement your mastery of the English language then TOK?
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Deleted
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Post by Deleted on Sept 15, 2005 18:26:08 GMT
Don't lie I bet you copied and pasted that TOK  |
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Post by ikar on Sept 15, 2005 18:55:23 GMT
Oh I meant that regular pass. services close after 23:45
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Deleted
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Post by Deleted on Sept 15, 2005 19:13:48 GMT
No chance of a diagram to supplement your mastery of the English language then TOK? . |
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Phil
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Post by Phil on Sept 15, 2005 19:42:00 GMT
A bit basic (Clive Feather I presume) - mais merci!!  |
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Post by Deleted on Sept 15, 2005 19:49:08 GMT
A bit basic (Clive Feather I presume) - mais merci!! Huh? I made this myself, based on what MetApp said about the layout of T5... |
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Phil
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Post by Phil on Sept 15, 2005 21:03:59 GMT
Aah- pardonnez moi monsieur ;D ;D ;D
(but it still LOOKS like one of clive's diagrams....)
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Chris M
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Post by Chris M on Sept 15, 2005 23:02:20 GMT
For those who prefer their diagrams a little prettier:  Based on TheOneKEA's diagram. |
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Colin
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Post by Colin on Sept 16, 2005 2:37:48 GMT
Oh I meant that regular pass. services close after 23:45 As no one seems to have noticed that you were actually asking if trains still use the loop after T4 closes at 23:45 (ignoring the current closure), i'll be nice and give you the answer!!! ;D In this instance, the trains go straight from Hatton Cross to Heathrow T123. They do not use the loop once T4 is closed. Mind you, I have a question related to this - will T4 continue to close early once all the engineering work is completed? |
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Deleted
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Post by Deleted on Sept 16, 2005 10:20:03 GMT
*deep breath* The works at Heathrow Terminal 5 for the Piccadilly Line involve the construction of a standard island-platform twin-track terminus, with a scissors crossover beyond the platform headwall and two reversing sidings beyond that. This layout allows trains to proceed into the w/b terminating platform, detrain their passengers, then run forward into either siding, allowing the driver to change ends and return to the e/b starting platform. Why go through all that tipping out and running into sidings and back out again when you could have a Walthamstow-type arrangement where the driver simply changes ends in the platform and goes? |
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Post by piccadillypilot on Sept 16, 2005 10:36:46 GMT
Why go through all that tipping out and running into sidings and back out again ... ? Because having the driver changes ends in the platform reduces the capacity of the station. While a train is standing in the platform another cannot get in until it leaves, that's at least four minutes (unless it's changed) for the driver to change ends and be ready to go, and that's the absolute minimum when the job is running straight and the train is working OK. Normal reversing time is slightly longer and if upon changing ends the driver finds a defect he's not blocking a platform while he sorts it out. He also doesn't have to detrain any passengers that may have boarded. |
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Post by russe on Sept 16, 2005 11:05:04 GMT
Why go through all that tipping out and running into sidings and back out again when you could have a Walthamstow-type arrangement where the driver simply changes ends in the platform and goes? I seem to remember occasionally seeing a weird 'Northbound' indication on the display screen at the bottom of the escalators at Walthamstow. Is there a reversing scissors or crossover to the north of the station? Russ |
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Post by ikar on Sept 16, 2005 13:05:46 GMT
Mind you, I have a question related to this - will T4 continue to close early once all the engineering work is completed? Dont think so The last flight that arrives to T4 is BA329 from Paris CDG at 21:55 (A320  ) The last flight that departs from T4 is BA163 to Tel Aviv at 22:30 (B763) |
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Post by Deleted on Sept 16, 2005 17:42:27 GMT
Why go through all that tipping out and running into sidings and back out again when you could have a Walthamstow-type arrangement where the driver simply changes ends in the platform and goes? I seem to remember occasionally seeing a weird 'Northbound' indication on the display screen at the bottom of the escalators at Walthamstow. Is there a reversing scissors or crossover to the north of the station? Russ Aha, my nearest station so I know it back to front! I don't believe there is a scissors crossover, the tunnels simply carry on for a short while under the One railway track, and at night they're used for stabling trains. The scissors crossover is west of the station as already stated. P.S. Sorry ikar, I honestly thought you meant Terminal 4 closing because of Terminal 5 development. It's a Friday! |
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Deleted
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Post by Deleted on Sept 18, 2005 0:49:05 GMT
Well, now I've seen the new track layout for Heathrow, it's time to put my "I LIKE TIMETABLES" hat back on I think! The previous service to Heathrow1/2/3 (with all trains running via T4) could be altered to run direct to and from T5 with the present Northfields reversers being extended to run via T4 and Heathrow1/2/3. Westbound, this would give 12 trains per hour to both Heathrow1/2/3 and T5, with 6 tph to T4. And returning Eastbound, we have 12 tph from T5 combining with 6 tph from T4 to give 18 tph back at Heathrow1/2/3. All tickity-boo so far, still with 6 tph to Rayners Lane and 3 tph to Uxbridge off-peak.... but there's the rub. What about during the Mon-Fri peaks, when the Rayners Lane branch needs an absolute minimum of 10 tph (currently at 12 tph and has been 15 tph) to cope with loadings? Perhaps this brings us back to an earlier discussion in another thread concerning the possible swapping of Ealing Bdwy and Rayners Lane branches between the Piccadilly and District. But it's very late, so I'm off to bed now! |
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