asdf wrote:

Huh? Grade-separating the scissors crossover is hardly a huge leap of
the imagination. I'm sure a lot more than 1 person has thought of it
before, and then only considered it a passing thought rather than an
invention!

So? That doesn't change the fact that with almost all of the
conflicting movements created by a flat terminal layout removed by
grade-separating the scissors crossover, line capacity can be massively
increased.

If it's so humdrum, why hasn't it been done yet?

On 21 May 2005 07:35:38 -0700, "TheOneKEA"
wrote:

asdf wrote:

Huh? Grade-separating the scissors crossover is hardly a huge leap of
the imagination. I'm sure a lot more than 1 person has thought of it
before, and then only considered it a passing thought rather than an
invention!

So? That doesn't change the fact that with almost all of the
conflicting movements created by a flat terminal layout removed by
grade-separating the scissors crossover, line capacity can be massively
increased.

If it's so humdrum, why hasn't it been done yet?

The idea may be trivial, but finding the will and the funding to
actually do it most certainly isn't!

Especially considering it would only really be necessary from (year
when new Vic stock is introduced) until (year when Crossrail 2 opens)
- projected at 7 years, though no doubt it will be nearer 20

On Sat, 21 May 2005, TheOneKEA wrote:

Tom Anderson wrote:

I might have lost the plot, but that seems to make no sense whatsoever
- making the line longer wouldn't have capacity implications. You could
run trains at exactly the same frequency (if you had a few more), so as
far as Brixton is concerned, it wouldn't be any different. Or am i
being stupid?

Extending the line and adding more stations increases the number of
passengers that the line must carry.

Right.

To ensure that loadings remain even, train frequency must be increased
to compensate, which is the problem at hand.

Okay. I don't understand that - why does the frequency have to increase?

All Victoria Line trains that can be used are in use, AFAIK. The only
way to get more trains is to build them - the 2009TS.

That's very true - even if frequency stays the same, on a longer line,
you'd need more trains.

However, what i really want to know is ...

A loop at Herne Hill is not the only way to increase capacity on the
Vic - a flying terminus would do the job just as well, without the
pain of turning trains around.

What the hell is a flying terminus? I'm getting visions of some sort of
Hayao Miyazaki sort of affair ...

http://216.55.161.203/theonekea/unde...g-terminus.txt

Ah, i see. Very good.

The person who invented this has done the math and discovered that
reversing capacity on this terminal layout is very high - capacity is
only limited by the run in time + dwell time + run out time; if these
values are kept low, frequencies as high as 40tph can be contemplated.

That's encouraging.

We talked about termini a while ago: there's a thread called "Diesel
Electric Trains on CrossRail" that veered off into terrminal arrangements
on the Victoria line (maybe some sort of transport version of Godwin's
law?), where James - if that is indeed his real name - suggested that the
two optimal termini are the loop and what we call the 'Sao Paolo' or, more
specifically, 'Corinthians-Itaquera', (or, more usefully, something like
'double-island three-track two-rank') layout, which looks like:

D
/-----\
C / ### +----
---+ A----+
\ ### +----
\-----/
B

Not the greatest diagram ever (in particular, there are links between the
junctions just outside the platforms, which i don't make at all obvious),
but trains coming in from the east can either go into the reversing road
in the middle (A), or the westbound road at the bottom (B). Trains in the
reversing road just back out and head back east; trains in the westbound
road run on to the reversing road on the left (C), then turn round and
come back into the eastbound road at the top (D), before heading east
again. The upshot of all this is that there are no conflicting movements -
while the first train is monkeying about in the reversing road, a second
train can be trundling round the outside route.

SubTalk has the skinny:

http://talk.nycsubway.org/perl/read?subtalk=713864

Says they can do 40 tph with it, and Alstom claims they can do 51 tph with
it.

The discussion says that something called a '4-track relay terminal with a
2-track relay' used to exist at Park Row on the New York subway. No idea
what that is, but the poster seemed to be impressed.

tom

--
I don't know kung fu, I am kung fu.

Tom Anderson wrote:
On Sat, 21 May 2005, TheOneKEA wrote:

Tom Anderson wrote:

I might have lost the plot, but that seems to make no sense
whatsoever - making the line longer wouldn't have capacity
implications. You could run trains at exactly the same frequency (if
you had a few more), so as far as Brixton is concerned, it wouldn't
be any different. Or am i being stupid?

Extending the line and adding more stations increases the number of
passengers that the line must carry.

Right.

To ensure that loadings remain even, train frequency must be increased
to compensate, which is the problem at hand.

Okay. I don't understand that - why does the frequency have to increase?

Because, given that the vast majority of passengers are travelling to
the central area (say Victoria - KXSP), the passengers from the new,
extension stations are using capacity in the central area which isn't
available.

The Victoria line is essentially full at the moment. If any new stations
are added (e.g. to the south), the trains will already be partly filled
up by the time they reach the current start of the line (e.g. Brixton).
With an extension, the point where they become totally full will be
further out than before (e.g. Vauxhall as opposed to Victoria), and so
passengers further in than this new "full point" (e.g. Pimlico) will
simply be unable to board the trains as there will be no available
capacity. Therefore frequency must be increased to allow the existing
passengers in the central area to board the trains.

--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

On Sat, 21 May 2005, Dave Arquati wrote:

Tom Anderson wrote:
On Sat, 21 May 2005, TheOneKEA wrote:

Tom Anderson wrote:

I might have lost the plot, but that seems to make no sense whatsoever -
making the line longer wouldn't have capacity implications. You could run
trains at exactly the same frequency (if you had a few more), so as far
as Brixton is concerned, it wouldn't be any different. Or am i being
stupid?

Extending the line and adding more stations increases the number of
passengers that the line must carry.

Right.

To ensure that loadings remain even, train frequency must be increased to
compensate, which is the problem at hand.

Okay. I don't understand that - why does the frequency have to increase?

Because, given that the vast majority of passengers are travelling to the
central area (say Victoria - KXSP), the passengers from the new, extension
stations are using capacity in the central area which isn't available.

Aaah! I see. Yes, that's rather obvious when you put it like that, sorry.

The Victoria line is essentially full at the moment.

Next question, then - how come? It has a pretty decent 28.5 tph, it's the
shortest proper line in the whole network, and all but one of its stations
are on other lines as well!

For northbound trais to be be full at Victoria, Brixton, Stockwell,
Vauxhall and Pimlico would have to be generating as many passengers as all
the Northern line stations from Morden to Kennington put together, or the
Piccadilly line stations from Cockfosters to Caledonian Road. I don't know
those areas terribly well, and i realise that at least some of them are
very densely populated areas, but that seems quite surprising. Is it
because there are few people getting off the line before central London? I
guess a lot of Picc passengers switch to the Vic at Finsbury Park, and
perhaps Northern passengers to the Vic at Stockwell! Or is the Victoria
line picking up a lot of passengers from the suburban railway network?

tom

--
Who would you help in a fight, Peter van der Linden or Bill Gates?

In article , Tom
Anderson writes
I'm just a little irked that they didn't build the stuff in that area a
bit more smoothly when they had the chance (with the WLL further to the
east, for example). I'm not too hot on my history, though; the WLL
probably predates the District line.

It does: the original District Line came west from Gloucester Road and
HSK (converging routes) then diverged to meet the WLL facing both north
and south.

Initially there was no station on the middle section. Earl's Court was
built later, and was initially on the *east* side of the road; it got
moved west later.

--
Clive D.W. Feather | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Please reply to the Reply-To address, which is:

Tom Anderson wrote:
On Sat, 21 May 2005, Dave Arquati wrote:
(snip)
The Victoria line is essentially full at the moment.


Next question, then - how come? It has a pretty decent 28.5 tph, it's
the shortest proper line in the whole network, and all but one of its
stations are on other lines as well!

For northbound trais to be be full at Victoria, Brixton, Stockwell,
Vauxhall and Pimlico would have to be generating as many passengers as
all the Northern line stations from Morden to Kennington put together,
or the Piccadilly line stations from Cockfosters to Caledonian Road. I
don't know those areas terribly well, and i realise that at least some
of them are very densely populated areas, but that seems quite
surprising. Is it because there are few people getting off the line
before central London? I guess a lot of Picc passengers switch to the
Vic at Finsbury Park, and perhaps Northern passengers to the Vic at
Stockwell! Or is the Victoria line picking up a lot of passengers from
the suburban railway network?

Well, according to the London Transport Strategy, in the morning peak,
the Victoria line is currently "very crowded" (i.e. operating in excess
of or near to planned capacity) northbound between Victoria and Green
Park, and southbound between Finsbury Park and King's Cross, and Euston
and Warren Street. Between Stockwell and Victoria it's just "busy"
northbound. The Northern line is "very crowded" northbound from Clapham
Common to Stockwell, after which it becomes "crowded" from there to
Kennington, suggesting a significant number of passengers transfer from
the Northern to the Victoria at Stockwell.

As I'd expect, the "very crowded" section north from Victoria indicates
that the line picks up an extremely high number of passengers from the
rail terminus, and it's on this Victoria - Green Park section that
capacity has been reached. Adding any stations further south would mean
those rail transfer passengers being left behind on the platform.
Unfortunately the diagrams in the Transport Strategy don't go beyond
Finsbury Park - but the Piccadilly southbound is at capacity already at
least between Finsbury Park and KXSP.

Incidentally, 2010 projections have the eastbound Piccadilly line
operating at capacity all the way from Barons Court to Hyde Park Corner
(presumably by which time, some passengers are so fed up they just get
off and get the bus!).


--
Dave Arquati
Imperial College, SW7
www.alwaystouchout.com - Transport projects in London

Tom Anderson wrote to uk.transport.london on Sun, 22 May 2005:

Next question, then - how come? It has a pretty decent 28.5 tph, it's the
shortest proper line in the whole network, and all but one of its stations
are on other lines as well!

Northbound trains usually have a little spare capacity until they reach
Victoria, at which point they invariably fill fuller than is
comfortable! I don't know at what point you begin to be able to breathe
again, but I assume at Kings Cross!

For northbound trais to be be full at Victoria, Brixton, Stockwell,
Vauxhall and Pimlico would have to be generating as many passengers
as all the Northern line stations from Morden to Kennington put
together,

A great many people change on to the Vic at Stockwell, probably because
it is a great deal quicker across London than the Northern Line is, and
if you are going to (e.g.) King's Cross, it's enough quicker to make
changing worth while. You can usually get a seat at Brixton, unless a
train has been cancelled, but in peak hours it's often standing-room
only after Stockwell.
--
"Mrs Redboots"
http://www.amsmyth.demon.co.uk/
Website updated 3 April 2005

In article , (Dave Arquati)
wrote:

Well, according to the London Transport Strategy, in the morning peak,
the Victoria line is currently "very crowded" (i.e. operating in excess
of or near to planned capacity) northbound between Victoria and Green
Park, and southbound between Finsbury Park and King's Cross, and Euston
and Warren Street. Between Stockwell and Victoria it's just "busy"
northbound. The Northern line is "very crowded" northbound from Clapham
Common to Stockwell, after which it becomes "crowded" from there to
Kennington, suggesting a significant number of passengers transfer from
the Northern to the Victoria at Stockwell.

As I'd expect, the "very crowded" section north from Victoria indicates
that the line picks up an extremely high number of passengers from the
rail terminus, and it's on this Victoria - Green Park section that
capacity has been reached. Adding any stations further south would mean
those rail transfer passengers being left behind on the platform.
Unfortunately the diagrams in the Transport Strategy don't go beyond
Finsbury Park - but the Piccadilly southbound is at capacity already at
least between Finsbury Park and KXSP.

IME a very large proportion of every Victoria Line train get on and off at
Oxford Circus.

--
Colin Rosenstiel

Tom Anderson wrote:

The Victoria line is essentially full at the moment.

Next question, then - how come? It has a pretty decent 28.5 tph, it's the
shortest proper line in the whole network, and all but one of its stations
are on other lines as well!

For northbound trais to be be full at Victoria, Brixton, Stockwell,
Vauxhall and Pimlico would have to be generating as many passengers as all
the Northern line stations from Morden to Kennington put together, or the
Piccadilly line stations from Cockfosters to Caledonian Road. I don't know
those areas terribly well, and i realise that at least some of them are
very densely populated areas, but that seems quite surprising. Is it
because there are few people getting off the line before central London? I
guess a lot of Picc passengers switch to the Vic at Finsbury Park, and
perhaps Northern passengers to the Vic at Stockwell! Or is the Victoria
line picking up a lot of passengers from the suburban railway network?

I guess it could be a factor. If I were commuting up through Brixton to
Victoria and then needed the tube, I'd be inclined to get off at Brixton and
join the Victoria Line there rather than go through the squeeze at Victoria.
I'm not sure how fast the Balham - Stockwell route is but there could be
passengers using that as an alternative. Commuter trains at Vauxhaul have
often shed quite a few there at peak hours.