Clive D. W. Feather wrote:
In article , Peter
Frimberley writes
If I recall correctly, the T4 loop does include a straight section
somewhere near where, at the time of it's construction, they expected
a future T5 to be. However the T5 that's being built is considerably
larger and in a different place than the T5 foreseen back then.

Correct.

AIUI there is a short enlargement (approx 30ft length) of the running
tunnel to station tunnel size on this section, with (possibly) a
platform, but certainly a passageway leading to an access shaft. I'm
not sure if the shaft contains an emergency exit (possible, given the
interstation distance T4-T123), or ventilation equipment, or is just
left over from construction of the loop. This can be seen on the west
side of a train (i.e. left) looking out around halfway between T4 and
T123, and is (or was, pre-closure) quite brightly lit.

In message . com, Harry
G writes

AIUI there is a short enlargement (approx 30ft length) of the running
tunnel to station tunnel size on this section, with (possibly) a
platform, but certainly a passageway leading to an access shaft. I'm
not sure if the shaft contains an emergency exit (possible, given the
interstation distance T4-T123), or ventilation equipment, or is just
left over from construction of the loop. This can be seen on the west
side of a train (i.e. left) looking out around halfway between T4 and
T123, and is (or was, pre-closure) quite brightly lit.

Doesn't matter how many time you say it - doesn't make it true

See my other post.
--
Steve Fitzgerald has now left the building.
You will find him in London's Docklands, E16, UK
(please use the reply to address for email)

Olof Lagerkvist wrote:
wrote:

Geography? Have you looked where Terminals 4 and 5 actually are?


Thanks for that informative reponse.

Are the terminals really so far apart that a three station loop would
have been impractical? It just seems a more logical service pattern
than some loop, some terminating.

Look at Heathrow on Google Map:
http://maps.google.com/maps?&om=1&z=...+airpo rt,+uk


You can see the new T5 taking shape about 1 ½ mile or someting west of
the T 1-2-3 station.

If you then look at the locations of T1-2-3, T4, T5 and Hatton Cross
stations I think you realize that a big loop through all of the stations
would not be realistic.

But the again you have a point about the service pattern getting far
more complex to the passangers, maybe it would have better to cut of the
south-eastern part of the current loop and drive the T4 trains via
T1-2-3 and then terminating and reversing at T4. That would give
HX-T123-T4 or HX-T123-T5 services, both terminating and reversing out
the same way they got in and easy to read and understand line diagrams.

It might be simpler, but there are probably capacity implications - loop
terminals have a higher throughput than dead ends, and the Picc is quite
frequent to Heathrow.

There is a long-standing (but currently rather pie-in-the-sky) proposal
for a loop at the end of the Victoria line from Brixton via Herne Hill
and back to Brixton. This would allow a frequency increase on the line
because the scissors crossover at the approach to Brixton is a limiting
factor in Victoria line capacity.

--
Dave Arquati
www.alwaystouchout.com - Transport projects in London

John B wrote:
Dave Arquati wrote:
For details of TfL's subsidiaries see:
http://www.tfl.gov.uk/tfl/subsidiaries.asp
(also see the link to an organisational chart on that page)
Although from an internal view, it's somewhat different to what that
organisational chart implies (which just explains how the companies are
related to each other, rather than how TfL actually operates).

Practically, TfL is divided into London Underground, London Rail,
Corporate and Surface Transport (just to make things seem more complicated).


So are DLR and Tramlink lumped together with the buses in Surface
Transport, then?

Essentially, DLR is part of London Rail, and Tramlink is part of London
Buses (which is in turn part of Surface).

However, it's not even quite that simple because of the private
companies involved. Really, the trams section is London Trams, which
manages the concession awarded to Tramtrack Croydon Ltd to operate
Croydon Tramlink, and also plans new tram services. Similarly, DLR
(within London Rail) manages the concessions awarded to Serco Docklands,
and the construction/maintenance concessionaires for the Lewisham, City
Airport and Woolwich Arsenal extensions.

--
Dave Arquati
www.alwaystouchout.com - Transport projects in London

On Thu, 28 Sep 2006 19:53:29 GMT, "Richard J."
wrote:

Stephen Farrow wrote:
John B wrote:
Stephen Farrow wrote:
But that implies that they got to T123, and then to T4, where
they terminate. Which isn't the case.
Are you suggesting that under the proposed service pattern all
Heathrow trains *won't* call at T123?


They will call at T123, but only /after/ they've called at T4

Sure, but the point still stands that all Heathrow trains will call
at T123.

The point is what to tell passengers so as to deliver them to their
destination as quickly as possible (important if you're catching a
plane).

That's probably best dealt with on an ad hoc basis by the drivers at
HX.

On a loop train with a T5 train immediately behind, "passengers for
T1,2,3,5 change here", frex.

--
James Farrar
. @gmail.com

Dave Arquati wrote:
Olof Lagerkvist wrote:

You can see the new T5 taking shape about 1 ½ mile or someting
west of the T 1-2-3 station.

If you then look at the locations of T1-2-3, T4, T5 and Hatton
Cross stations I think you realize that a big loop through all of
thestations would not be realistic.

But the again you have a point about the service pattern getting
far more complex to the passangers, maybe it would have better to
cut [off] the south-eastern part of the current loop and drive the T4
trains via T1-2-3 and then terminating and reversing at T4. That
would give HX-T123-T4 or HX-T123-T5 services, both terminating and
reversing out the same way they got in and easy to read and
understand line diagrams.

It might be simpler, but there are probably capacity implications -
loop terminals have a higher throughput than dead ends, and the Picc
is quite frequent to Heathrow.

T4 frequency will be (I believe) every 15 minutes, so normally a
dead-end branch would be able to cope, but in this case it's only single
track and quite long, which would make the timing very tight.

It's theoretically true that a loop has a higher capacity than a dead
end, but because you have to keep the trains running continuously, there
is no opportunity to recover a disrupted service by turning trains round
quicker than usual. Hence the reliability of the service can suffer,
which tends to absorb the theoretical capacity increase.

There is a long-standing (but currently rather pie-in-the-sky)
proposal for a loop at the end of the Victoria line from Brixton via
Herne Hill and back to Brixton. This would allow a frequency
increase on the line because the scissors crossover at the approach to
Brixton is a limiting factor in Victoria line capacity.

Wouldn't it be cheaper to achieve that by building a few reversing
sidings south of Brixton? And you'd have better reliability that way.
--
Richard J.
(to e-mail me, swap uk and yon in address)

Richard J. wrote:
Wouldn't it be cheaper to achieve that by building a few reversing
sidings south of Brixton? And you'd have better reliability that way.

A flying terminus would be better - more expensive, of course, but far
better, as it would be able to absorb capacity increases with ease, far
beyond the nominal capacity of the physical route of the Victoria Line.

In article . com,
(John B) wrote:

Stephen Farrow wrote:
But that implies that they got to T123, and then to T4, where
they terminate. Which isn't the case.

Are you suggesting that under the proposed service pattern all
Heathrow trains *won't* call at T123?

They will call at T123, but only /after/ they've called at T4 (and
waited for several minutes since T4 is the nominal terminus).

Will it still be called T123 once T2 is closed and demolished?

--
Colin Rosenstiel

In message ,
Colin Rosenstiel writes

Will it still be called T123 once T2 is closed and demolished?

AIUI, the plan is to call the rebuilt complex "Heathrow East" - but that
rather begs the question of whether (and how) the other terminals should
be numbered!

--
Paul Terry

Colin Rosenstiel wrote:

Will it still be called T123 once T2 is closed and demolished?

Changing all the signs would cost money and offer no benefit... apart from
preventing all the people who are not going to Terminal 2 any more from not
going to the place where it used to be, instead of not going to the places
where it never was.