On Sep 11, 9:53*am, "Richard J." wrote:

Bill Bolton wrote on 11 September 2009
09:20:55 ...

GazK wrote:
Don't forget the loss of capacity due to increased dwell times loading
a DD train...

Dwell time issue only become significant if the train a significant
percentage of the passenger carrying capacity of the DD train
boards/alights at every stop on the route.

In most systems that doesn't happen, with large boarding/alighting
flows only occurring at a relatively small number of stops along the
route.

This isn't "most systems". *It's London, and all 6 of the central area
stations on Crossrail (the ones where 24tph are currently planned)
*will* have heavy boarding/alighting flows.

Indeed - it's going to be busy.

On Sep 10, 11:38*pm, wrote:
On Thu, 10 Sep 2009 17:33:10 +0100, Tom Barry
wrote:





wrote:
On Wed, 9 Sep 2009 16:06:03 +0100
"Basil Jet" wrote:
wrote:
*sigh* I hate to break this pre-GCSE news to you, but the area of the
shaft of a cylinder increases *linearly* with increasing radius, not
as the square of it so the cost of the lining will not go up like
that. The formula you want incidentaly is 2*pi*r*h. So before you
post anymore bull**** pretending your in-the-biz you might want to
revisit your school books first.
It's a good job you didn't write those schoolbooks, otherwise they'd say
that a one-inch diameter pipe and a five-metre diameter pipe need walls
which are the same thickness.

Remind me how a 10% increase in diameter size required to fit UIC gauge trains
in the tunnel in mostly self supporting london clay is going to cost so much
more because of huge extra lining thickness apparently required.

B2003

I hate to leap to the defence of either of you, but I suspect Bruce's
comment about the costs of *excavation* is more relevant than the costs
of lining. *The area of lining is proportionate to the radius of the
bore, but the weight of excavated material is proportionate to the
square of the radius, as are transport and disposal costs. *Add in the
strengthening required for the greater load borne by the lining for a
bit more £ on top, this obviously includes transport costs for whatever
they're using for the lining.

What's missing in this back-and-forth ranting is an estimation of the
proportion of Crossrail costs that are directly related to the
tunnelling rather than the station fit-out, land acquisition,
electrification, trains etc. *If it's only 5% of the costs, then going
large won't break that much of the bank. *If it's 50%, then you're
talking in £billions.

One other benefit of double-deck trains, by the way, is shorter train
lengths for the same capacity (which saves money on station lengths, but
not in the capacity of escalators etc.). That's at the expense of dwell
times, though, unless you do something really clever like having
double-height platforms with doors on the upper deck too (I like the
sound of that, actually).

Tom

Would there be sufficient space to build larger tunnels, or will they
be so deep as to avoid other tunnels, foundations etc. ?

Your specific question, I cannot answer. IIRC Crossrail will
something of a roller coaster. It has to a avoid considerable "stuff"
that is already along its route!

On Fri, 11 Sep 2009 08:53:29 GMT, "Richard J."
wrote:

In most systems that doesn't happen, with large boarding/alighting
flows only occurring at a relatively small number of stops along the
route.

Bill Bolton
Sydney, Australia

This isn't "most systems". It's London, and all 6 of the central area
stations on Crossrail (the ones where 24tph are currently planned)
*will* have heavy boarding/alighting flows.

I can well believe that. In central Paris, RER line "A" has 50 second
dwell times (compared to an average of 18 seconds on the métro).

On Sep 10, 11:38*pm, wrote:
On Thu, 10 Sep 2009 17:33:10 +0100, Tom Barry
wrote:





wrote:
On Wed, 9 Sep 2009 16:06:03 +0100
"Basil Jet" wrote:
wrote:
*sigh* I hate to break this pre-GCSE news to you, but the area of the
shaft of a cylinder increases *linearly* with increasing radius, not
as the square of it so the cost of the lining will not go up like
that. The formula you want incidentaly is 2*pi*r*h. So before you
post anymore bull**** pretending your in-the-biz you might want to
revisit your school books first.
It's a good job you didn't write those schoolbooks, otherwise they'd say
that a one-inch diameter pipe and a five-metre diameter pipe need walls
which are the same thickness.

Remind me how a 10% increase in diameter size required to fit UIC gauge trains
in the tunnel in mostly self supporting london clay is going to cost so much
more because of huge extra lining thickness apparently required.

B2003

I hate to leap to the defence of either of you, but I suspect Bruce's
comment about the costs of *excavation* is more relevant than the costs
of lining. *The area of lining is proportionate to the radius of the
bore, but the weight of excavated material is proportionate to the
square of the radius, as are transport and disposal costs. *Add in the
strengthening required for the greater load borne by the lining for a
bit more £ on top, this obviously includes transport costs for whatever
they're using for the lining.

What's missing in this back-and-forth ranting is an estimation of the
proportion of Crossrail costs that are directly related to the
tunnelling rather than the station fit-out, land acquisition,
electrification, trains etc. *If it's only 5% of the costs, then going
large won't break that much of the bank. *If it's 50%, then you're
talking in £billions.

One other benefit of double-deck trains, by the way, is shorter train
lengths for the same capacity (which saves money on station lengths, but
not in the capacity of escalators etc.). That's at the expense of dwell
times, though, unless you do something really clever like having
double-height platforms with doors on the upper deck too (I like the
sound of that, actually).

Tom

Would there be sufficient space to build larger tunnels, or will they
be so deep as to avoid other tunnels, foundations etc. ?

Your specific question, I cannot answer. IIRC Crossrail will be
something of a roller coaster. It has to a avoid considerable
"stuff"
that is already along its route!

"Richard J." wrote:

This isn't "most systems". It's London, and all 6 of the central area
stations on Crossrail

London isn't as special as you seem to think. 6 stations in a central
area with heavy traffic is nothing particularly unusual for DD train
operations.

Bill Bolton
Sydney, Australia

Bill Bolton wrote on 12 September 2009
"Richard J." wrote:
Bill Bolton wrote on 11 September 2009
GazK wrote:

Don't forget the loss of capacity due to increased dwell times loading
a DD train...

Dwell time issue only become significant if the train a significant
percentage of the passenger carrying capacity of the DD train
boards/alights at every stop on the route.

In most systems that doesn't happen, with large boarding/alighting
flows only occurring at a relatively small number of stops along the
route.

This isn't "most systems". It's London, and all 6 of the central area
stations on Crossrail

London isn't as special as you seem to think. 6 stations in a central
area with heavy traffic is nothing particularly unusual for DD train
operations.

I was contrasting it with your "most systems" comment. The point is
that if the stations with the heaviest passenger flows are in the
central section where you want the greatest train frequency, then peak
trains per hour will be limited by the increased dwell times there, as
GazK pointed out. The dwell time issue doesn't go away just because
stations further out from the centre don't have that problem.

--
Richard J.
(to email me, swap 'uk' and 'yon' in address)

In uk.transport.london message , Thu,
10 Sep 2009 17:33:10, Tom Barry posted:

One other benefit of double-deck trains, by the way, is shorter train
lengths for the same capacity (which saves money on station lengths,
but not in the capacity of escalators etc.). That's at the expense of
dwell times, though, unless you do something really clever like having
double-height platforms with doors on the upper deck too (I like the
sound of that, actually).

At busy stations, there can be a lower-deck platform on one side of the
train and an upper-deck platform on the other side. At less busy
stations, rely on the carriages' internal stairs.

--
(c) John Stockton, Surrey, UK. Turnpike v6.05 MIME.
Web URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links.
Proper = 4-line sig. separator as above, a line exactly "-- " (SonOfRFC1036)
Do not Mail News to me. Before a reply, quote with "" or " " (SonOfRFC1036)

On Sep 12, 11:08*am, "Richard J." wrote:
Bill Bolton wrote on 12 September 2009





"Richard J." wrote:
Bill Bolton wrote on 11 September 2009
GazK wrote:
Don't forget the loss of capacity due to increased dwell times loading
a DD train...
Dwell time issue only become significant if the train a significant
percentage of the passenger carrying capacity of the DD train
boards/alights at every stop on the route.

In most systems that doesn't happen, with large boarding/alighting
flows only occurring at a relatively small number of stops along the
route.
This isn't "most systems". *It's London, and all 6 of the central area
stations on Crossrail
London isn't as special as you seem to think. *6 stations in a central
area with heavy traffic is nothing particularly unusual for DD train
operations.

I was contrasting it with your "most systems" comment. *The point is
that if the stations with the heaviest passenger flows are in the
central section where you want the greatest train frequency, then peak
trains per hour will be limited by the increased dwell times there, as
GazK pointed out. *The dwell time issue doesn't go away just because
stations further out from the centre don't have that problem.


The Z22500 EMUs on RER Line E in Paris (and the similar MI2N on RER
line A) would be the way to go, each coach having three sets of extra-
wide double doors. This comes at the penalty of some seating of
course.

"Richard J." wrote:

The point is that if the stations with the heaviest passenger flows
are in the central section where you want the greatest train
frequency, then peak trains per hour will be limited by the
increased dwell times there

There is clearly a trade off between frequency and capacity, however I
find it very hard to believe that in the Crossrail context the whole
load of a train is going to change over at each of the 6 CBD stations.
In practice it doesn't work that way on *any* system and with good
loading vestibule design on DD rolling stock, significant number of
passengers can be handled at each heavily traffic station without the
dwell time impacting the *actual track capacity* in terms of people
moved.

CityRail does it in Sydney using an all DD fleet without any
particular problems.

The dwell time issue doesn't go away just because
stations further out from the centre don't have that problem.

Dwell time is simple not the issue that you are making it out to be.

Bill Bolton
Sydney, Australia

Andy writes:
The Z22500 EMUs on RER Line E in Paris (and the similar MI2N on RER
line A) would be the way to go, each coach having three sets of extra-
wide double doors. This comes at the penalty of some seating of
course.

Are their double-floor cars "mostly sitting" cars?

How well do double-floor cars work with "mostly standing" designs?

All of the double-floor cars I've seen in real life have clearly been
oriented towards seated passengers, and this obviously puts a big
restriction on their capacity.

Extremely crowded trains with mostly standing passengers can work
reasonable well because they have _so much_ door area (on some train
cars that I've seen, around 50% of the wall area is doors), that it's
possible for people to get on and off despite the crush loading. It
allows not just massive "bandwidth" for major stations, but also high
"accessibility" for some poor schmuck that just wants to get off at a
minor station, where even crossing the car to get to a very nearby door
is difficult.

But how would that work in a double-floor car? I can imagine that
something that was basically like two single-floor cars stacked
vertically could work, but obviously that would require a _massive_
amount of additional station infrastructure -- it would basically
require all stations to have double-floor platforms.

[Many Japanese commuter trains have some double floor cars e.g. "green
cars", but their capacity is quite restricted compared to the normal
single-floor cars]

-Miles

--
I'd rather be consing.