wrote:
Dave Arquati wrote:
Don't forget that an interchange (well, an H&C station on Wood Lane) is
already being built at White City, and will have been in operation for a
number of years before Crossrail ever appears in the area.

The other issues would be what to do with Hammersmith Depot and where
Circle Line trains should be stabled.
The stock requirement of the Circle (or whatever succeeded it)
operations would go down somewhat. The remaining stabling arrangements
could be to retain a stub towards Royal Oak along which trains could be
stabled; similarly, perhaps use could be made of the defunct Moorgate
Thameslink branch for expansion of the Farringdon sidings.

The new common S-stock should allow greater flexibility in where to
stable trains, so any more sidings needed could be distributed around
some other depots wherever a small expansion could occur.

--
The S-stock is something, the merrits of which, I have yet to be
convinced. Time will tell if the concept is acceptable.

I'm not yet convinced by the internal layouts, but the idea of a stock
that can go "anywhere" seems sensible when the future of the SSL network
is hazy.

If one dreams a little further with regard to CrossRail and the
Hammersmith branch: Imagine, if you, will a rebuilt connecting viaduct
at Hammersmith allowing CrossRail to reach Ealing Broadway and
Richmond.

I don't think I'd bother going that far. Taking over as far as
Hammersmith is probably OK because Crossrail serves several of the H&C's
most important destinations. However, it goes nowhere near Victoria and
is a bit of a walk from places like Monument in the City. We know that
Richmonders don't want Crossrail to replace their District service, and
Ealing Broadway will already have Crossrail.

Shared running would also be a very poor idea as the trains would be so
different and there would be the inevitable performance pollution.

The problem here is the purchase and demolition of all that has been
built in the intervening years. There is also the issue of the many
differing platform lengths en route to the two termini.

However, if there District Line was reduced to an Upminster to
Wimbledon service plus an Edgware Road to Kensington Olympia shuttle,
Circle Line operation would become simplicity itself!

Crossrail operation would be a lot more complicated, though!

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

Dave Arquati wrote:

I don't think I'd bother going that far. Taking over as far as
Hammersmith is probably OK because Crossrail serves several of the H&C's
most important destinations. However, it goes nowhere near Victoria and
is a bit of a walk from places like Monument in the City. We know that
Richmonders don't want Crossrail to replace their District service, and
Ealing Broadway will already have Crossrail.

Good points, against which I have no argument.


Shared running would also be a very poor idea as the trains would be so
different and there would be the inevitable performance pollution.

Shared running would only start east of Turnham Green. Interlining
with the North London Line should not be very difficult. It only has
about 3 to 4 trains per hour. The Piccadilly Line is a real problem.
Perhaps the solution to that would be to have CrossRail also take over
the Rayners Lane service. This would double Piccadilly Line service to
Heathrow.

The problem here is the purchase and demolition of all that has been
built in the intervening years. There is also the issue of the many
differing platform lengths en route to the two termini.

However, if there District Line was reduced to an Upminster to
Wimbledon service plus an Edgware Road to Kensington Olympia shuttle,
Circle Line operation would become simplicity itself!

Crossrail operation would be a lot more complicated, though!

Not really given the minimal amount of shared track, i.e. the NLL. I
don't think this idea is do-able, but it beats turning 24 tph back at
Paddington.


Adrian.

wrote:
Dave Arquati wrote:

I don't think I'd bother going that far. Taking over as far as
Hammersmith is probably OK because Crossrail serves several of the H&C's
most important destinations. However, it goes nowhere near Victoria and
is a bit of a walk from places like Monument in the City. We know that
Richmonders don't want Crossrail to replace their District service, and
Ealing Broadway will already have Crossrail.

Good points, against which I have no argument.

Shared running would also be a very poor idea as the trains would be so
different and there would be the inevitable performance pollution.

Shared running would only start east of Turnham Green. Interlining
with the North London Line should not be very difficult. It only has
about 3 to 4 trains per hour. The Piccadilly Line is a real problem.
Perhaps the solution to that would be to have CrossRail also take over
the Rayners Lane service. This would double Piccadilly Line service to
Heathrow.

Not sure exactly what you're suggesting here. Is it:
- Crossrail via Ladbroke Grove & Shepherd's Bush to Rayners Lane via
Ealing Common and to Richmond via Gunnersbury
- District continues to run to Ealing Broadway...?

That results in four western Crossrail branches with shared use between
Gunnersbury and Richmond, between Hammersmith and Turnham Green and
between Acton Town and Ealing Common!

One of the issues raised by the Montague report was that too many
branches at each end would mean poorer reliability, as it's more
difficult to ensure that trains arrive at the core section on time for
their path - making achievement of the 24tph core service difficult.
Having so much shared use to the west would be a recipe for disaster.
The beauty of taking over as far as Hammersmith is that it is
self-contained *and* reduces the number of services trying to interleave
on the northern Circle.

The problem here is the purchase and demolition of all that has been
built in the intervening years. There is also the issue of the many
differing platform lengths en route to the two termini.

However, if there District Line was reduced to an Upminster to
Wimbledon service plus an Edgware Road to Kensington Olympia shuttle,
Circle Line operation would become simplicity itself!
Crossrail operation would be a lot more complicated, though!

Not really given the minimal amount of shared track, i.e. the NLL. I
don't think this idea is do-able, but it beats turning 24 tph back at
Paddington.

I'd say four branches is complicated! Making good use of the 14tph
(24tph really would be a waste!!) seems eminently sensible - but I'd
rather have Crossrail built with those 14tph wasted to begin with, but
scope for future expansion, than see a bloated single-phase project sink.


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

On Fri, 4 Aug 2006, Dave Arquati wrote:

wrote:
Dave Arquati wrote:

Shared running would only start east of Turnham Green. Interlining
with the North London Line should not be very difficult. It only has
about 3 to 4 trains per hour. The Piccadilly Line is a real problem.
Perhaps the solution to that would be to have CrossRail also take over
the Rayners Lane service. This would double Piccadilly Line service to
Heathrow.

Not sure exactly what you're suggesting here. Is it:
- Crossrail via Ladbroke Grove & Shepherd's Bush to Rayners Lane via Ealing
Common and to Richmond via Gunnersbury
- District continues to run to Ealing Broadway...?

That results in four western Crossrail branches with shared use between
Gunnersbury and Richmond, between Hammersmith and Turnham Green and between
Acton Town and Ealing Common!

One of the issues raised by the Montague report was that too many
branches at each end would mean poorer reliability, as it's more
difficult to ensure that trains arrive at the core section on time for
their path - making achievement of the 24tph core service difficult.

This is all very true, and i'd agree that the suggested massive takeover
in the west would be a bad idea. However, i really can't believe that
Crossrail can only support *two* branches at each end - three should be
doable, even if not four.

In particular, if there was room for one inward train to wait on each
branch, it should be trivial - divide the hour into 30 2-minute slots,
group these into four, and allocate them one to each branch, plus a spare
(so trains go Shenfield, Dartford, Broxbourne, no train). Set up the
schedule so that each branch delivers a train at the appropriate time. If
a train is delayed, and misses its slot, it sits and waits until the next
empty slot comes round - which could be a spare slot, or a slot missed by
a delayed train on another branch. The worst-case wait would be four
minutes, if a train just missed its slot and had to wait for trains from
both other branches to go through. A slightly better arrangement might be
to group the slots into six five-slot bundles, with four trains and a
spare, so that the position of the spare slot with respect to each branch
changes; otherwise, you get worse delay behaviour on one branch.

In principle, this would work for more branches, but as you increase the
number of branches, the worst-case wait gets worse. Although, if you have
several branches missing slots, the average case might not ...

tom

--
Sapere aude!

Dave Arquati wrote:
wrote:
Dave Arquati wrote:

I don't think I'd bother going that far. Taking over as far as
Hammersmith is probably OK because Crossrail serves several of the H&C's
most important destinations. However, it goes nowhere near Victoria and
is a bit of a walk from places like Monument in the City. We know that
Richmonders don't want Crossrail to replace their District service, and
Ealing Broadway will already have Crossrail.

Good points, against which I have no argument.

Shared running would also be a very poor idea as the trains would be so
different and there would be the inevitable performance pollution.

Shared running would only start east of Turnham Green. Interlining
with the North London Line should not be very difficult. It only has
about 3 to 4 trains per hour. The Piccadilly Line is a real problem.
Perhaps the solution to that would be to have CrossRail also take over
the Rayners Lane service. This would double Piccadilly Line service to
Heathrow.

Not sure exactly what you're suggesting here. Is it:
- Crossrail via Ladbroke Grove & Shepherd's Bush to Rayners Lane via
Ealing Common and to Richmond via Gunnersbury
- District continues to run to Ealing Broadway...?

No, the Piccadilly would retain the 'fast pair' and continue to serve
Heathrow. Richmond, Ealing Broadway and Rayners Lane would be served
by CrossRail by way of Ladbroke Grove and a re-instated link at
Hammersmith. The District Line would become an Upminster to Wimbledon
and Edgware Road to Kensington Olympia Service.

That results in four western Crossrail branches with shared use between
Gunnersbury and Richmond, between Hammersmith and Turnham Green and
between Acton Town and Ealing Common!

The only shared use would be between Gunnersbury and Richmond.
CrossRail would utilize the trackes currently occupied by the District
Line.

One of the issues raised by the Montague report was that too many
branches at each end would mean poorer reliability, as it's more
difficult to ensure that trains arrive at the core section on time for
their path - making achievement of the 24tph core service difficult.
Having so much shared use to the west would be a recipe for disaster.
The beauty of taking over as far as Hammersmith is that it is
self-contained *and* reduces the number of services trying to interleave
on the northern Circle.

And I think that is a fair point. Whilst I think this conversation is
interesting, I don't see the idea I have outlined as a practical
option. The link at Hammersmith pretty much rules it out. But, under
this idea, Circle Line working becomes much simpler. The H&C goes away
and the District is less complex.

The problem here is the purchase and demolition of all that has been
built in the intervening years. There is also the issue of the many
differing platform lengths en route to the two termini.

However, if there District Line was reduced to an Upminster to
Wimbledon service plus an Edgware Road to Kensington Olympia shuttle,
Circle Line operation would become simplicity itself!
Crossrail operation would be a lot more complicated, though!

Not really given the minimal amount of shared track, i.e. the NLL. I
don't think this idea is do-able, but it beats turning 24 tph back at
Paddington.

I'd say four branches is complicated! Making good use of the 14tph
(24tph really would be a waste!!) seems eminently sensible - but I'd
rather have Crossrail built with those 14tph wasted to begin with, but
scope for future expansion, than see a bloated single-phase project sink.

Thank you for correcting my 24 tph! That is what 9 hours COBOL
progamming does to the brain! :-). And I agree, let's see CrossRail
built. We can campaign for more, and better, branches later.

Adrian.

Adrian Auer-Hudson, MIMIS wrote:
Dave Arquati wrote:
wrote:
Dave Arquati wrote:

I don't think I'd bother going that far. Taking over as far as
Hammersmith is probably OK because Crossrail serves several of the H&C's
most important destinations. However, it goes nowhere near Victoria and
is a bit of a walk from places like Monument in the City. We know that
Richmonders don't want Crossrail to replace their District service, and
Ealing Broadway will already have Crossrail.
Good points, against which I have no argument.

Shared running would also be a very poor idea as the trains would be so
different and there would be the inevitable performance pollution.
Shared running would only start east of Turnham Green. Interlining
with the North London Line should not be very difficult. It only has
about 3 to 4 trains per hour. The Piccadilly Line is a real problem.
Perhaps the solution to that would be to have CrossRail also take over
the Rayners Lane service. This would double Piccadilly Line service to
Heathrow.
Not sure exactly what you're suggesting here. Is it:
- Crossrail via Ladbroke Grove & Shepherd's Bush to Rayners Lane via
Ealing Common and to Richmond via Gunnersbury
- District continues to run to Ealing Broadway...?

No, the Piccadilly would retain the 'fast pair' and continue to serve
Heathrow. Richmond, Ealing Broadway and Rayners Lane would be served
by CrossRail by way of Ladbroke Grove and a re-instated link at
Hammersmith. The District Line would become an Upminster to Wimbledon
and Edgware Road to Kensington Olympia Service.

Hmm... with so many branches, you divide the train frequency
unacceptably; you could only achieve something like 6tph to Rayners
Lane, 4tph to Ealing and 4tph to Richmond.

I'm also unsure whether Olympia can handle the 8tph to Edgware Road.
Another irritation for passengers would be the need to change trains on
journeys from Hammersmith to Victoria etc, and an awkward change at that
(Earl's Court or South Kensington).

That results in four western Crossrail branches with shared use between
Gunnersbury and Richmond, between Hammersmith and Turnham Green and
between Acton Town and Ealing Common!

The only shared use would be between Gunnersbury and Richmond.
CrossRail would utilize the trackes currently occupied by the District
Line.

There would also be a small amount of shared use at Rayners Lane, where
Crossrail trains would have to unload in the westbound platform and
reverse in the sidings as Piccadilly services do now (unless Crossrail
works went beyond mere platform-lengthening and siding extension to full
isolation by creating a single line from the junction into the station).

One of the issues raised by the Montague report was that too many
branches at each end would mean poorer reliability, as it's more
difficult to ensure that trains arrive at the core section on time for
their path - making achievement of the 24tph core service difficult.
Having so much shared use to the west would be a recipe for disaster.
The beauty of taking over as far as Hammersmith is that it is
self-contained *and* reduces the number of services trying to interleave
on the northern Circle.

And I think that is a fair point. Whilst I think this conversation is
interesting, I don't see the idea I have outlined as a practical
option. The link at Hammersmith pretty much rules it out. But, under
this idea, Circle Line working becomes much simpler. The H&C goes away
and the District is less complex.

You could still simplify SSL operation just by taking over to
Hammersmith, I think. The easy option would be to simply extend
Wimblewares to Whitechapel/Barking; I also quite like Bob's idea of two
interposed loops (Wimbledon - Victoria - Aldgate - Edgware Road -
Wimbledon and Whitechapel - Victoria - Edgware Road - Whitechapel) if
the frequencies could be sorted out.

The problem here is the purchase and demolition of all that has been
built in the intervening years. There is also the issue of the many
differing platform lengths en route to the two termini.

However, if there District Line was reduced to an Upminster to
Wimbledon service plus an Edgware Road to Kensington Olympia shuttle,
Circle Line operation would become simplicity itself!
Crossrail operation would be a lot more complicated, though!
Not really given the minimal amount of shared track, i.e. the NLL. I
don't think this idea is do-able, but it beats turning 24 tph back at
Paddington.
I'd say four branches is complicated! Making good use of the 14tph
(24tph really would be a waste!!) seems eminently sensible - but I'd
rather have Crossrail built with those 14tph wasted to begin with, but
scope for future expansion, than see a bloated single-phase project sink.

Thank you for correcting my 24 tph! That is what 9 hours COBOL
progamming does to the brain! :-). And I agree, let's see CrossRail
built. We can campaign for more, and better, branches later.

Adrian.



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