"Alex Terrell" wrote in message
om...
"Bob" wrote in message
...
"Alex Terrell" wrote in message
om...
The specialised 186mph trains are due to start running from stations
in
Kent
to London along the Channel Tunnel Rail Link (CTRL), but ministers
are
still
arguing over which rolling stock to order.

Over engineered trains again. Would it not be eaiser to use the line
at 160mph and add 5 minutes to the London Paris journey time?


It would be even easier to run it at 90mph and use MK1 EMUs (lots of
them
going spare now), but that would be missing the point of the line,
wouldn't
it?
Slam door?

I suspect train cost is proportional to kinetic energy, i.e rises with
the square of the velocity. So there will be an optimum speed.

It's about 70 miles St Pancras to the tunnel, so:

180 mph = 23 min
160 mph = 26 min
150 mph = 28 min
140 mph = 30 min
90 mph = 47 min

Trains running at 140 mph adds only 5 min, but makes the commuter
problem much, much easier.

(Velocities are max, I know average speeds will be less, but the logic
is the same).

In my world, 30-23 is 7 not 5.

Anyway, the point of the line is to cut as much as possible off the journey
time between London and Paris / Brussels. Running trains at 186mph is the
plan - your commuter trains at 140mph would get in the way.

Since the technology exists for 186mph running, why not just build the damn
trains instead of messing things up with a stupid fudge. Your kind of
thinking is why things always turn to crap in this country.

"Bob" wrote in message
...


Anyway, the point of the line is to cut as much as possible off the
journey
time between London and Paris / Brussels. Running trains at 186mph is the
plan - your commuter trains at 140mph would get in the way.

Half the CTRL-DS trains will turn off at Ebbsfleet, and AIUI the line limit
between St Pancras and Ebbsfleet will be 140 mph or less. Between Ebbsfleet
and Ashford the peak demand for the forseeable future will be 4 tph for E*
and 4 tph for CTRL-DS, and the line will be perfectly capable of
accommodating these, even with a 186/140 mph speed mix.
Peter

"Peter Masson" wrote in message ...
"Bob" wrote in message
...


Anyway, the point of the line is to cut as much as possible off the
journey
time between London and Paris / Brussels. Running trains at 186mph is the
plan - your commuter trains at 140mph would get in the way.

Half the CTRL-DS trains will turn off at Ebbsfleet, and AIUI the line limit
between St Pancras and Ebbsfleet will be 140 mph or less. Between Ebbsfleet
and Ashford the peak demand for the forseeable future will be 4 tph for E*
and 4 tph for CTRL-DS, and the line will be perfectly capable of
accommodating these, even with a 186/140 mph speed mix.
Peter

Good point - especially valid if they run the Eurostars in pairs, one
to Brussels and one to Paris.

I also think St Pancras to Ebbsfleet is mostly tunnel, where the
trains are speed limited by the design of the tunnel.

So why is this an issue? Why the delay?

In message
(Alex Terrell) wrote:

"Peter Masson" wrote in message
...
"Bob" wrote in message
...


Anyway, the point of the line is to cut as much as possible off the
journey
time between London and Paris / Brussels. Running trains at 186mph is
the plan - your commuter trains at 140mph would get in the way.

Half the CTRL-DS trains will turn off at Ebbsfleet, and AIUI the line
limit between St Pancras and Ebbsfleet will be 140 mph or less. Between
Ebbsfleet and Ashford the peak demand for the forseeable future will be 4
tph for E* and 4 tph for CTRL-DS, and the line will be perfectly capable
of accommodating these, even with a 186/140 mph speed mix. Peter

Good point - especially valid if they run the Eurostars in pairs, one
to Brussels and one to Paris.

They already do, the two services depart Waterloo 5 minutes apart, all to do
with paths through the Channel Tunnel. IIRC one Eurostar requires two
shuttle paths but a 'flight' of two Eurostars only requires 3 paths, thus
saving a path that Eurotunnel can use either for shuttles or freight. This
obviously has the same effect on the CTRL: 2 fast trains close together, then
the next two 25 minutes later, should be fairly easy to flight the slower
trains in the resulting gaps.


--
Graeme Wall
This address is not read, substitute trains for rail.
Transport Miscellany at http://www.greywall.demon.co.uk/rail/index.html

"Graeme Wall" wrote in message
...

Good point - especially valid if they run the Eurostars in pairs, one
to Brussels and one to Paris.

They already do, the two services depart Waterloo 5 minutes apart, all to
do
with paths through the Channel Tunnel. IIRC one Eurostar requires two
shuttle paths but a 'flight' of two Eurostars only requires 3 paths, thus
saving a path that Eurotunnel can use either for shuttles or freight.
This
obviously has the same effect on the CTRL: 2 fast trains close together,
then
the next two 25 minutes later, should be fairly easy to flight the slower
trains in the resulting gaps.

They used to time E* like this, but since phase 1 of the CTRL opened this
pairing of departures has been the exception rather than the rule. There was
apparently a problem at Waterloo International with trying to load up to
1500 passengers on to two trains on opposite sides of an island platform -
congestion and the risk of sending Brussels passengers to Paris and vv. In
the current timetable the only paired departures seem to be:
0629 Paris/0634 Brussels
1039 Paris/1042 Brussels
1909FO Paris/1912 Brussels
1034Su Paris/1037Su Brussels.
Peter

"Peter Masson" wrote in message
...

"Graeme Wall" wrote in message
...

Good point - especially valid if they run the Eurostars in pairs, one
to Brussels and one to Paris.

They already do, the two services depart Waterloo 5 minutes apart, all to
do
with paths through the Channel Tunnel. IIRC one Eurostar requires two
shuttle paths but a 'flight' of two Eurostars only requires 3 paths, thus
saving a path that Eurotunnel can use either for shuttles or freight.
This
obviously has the same effect on the CTRL: 2 fast trains close together,
then
the next two 25 minutes later, should be fairly easy to flight the slower
trains in the resulting gaps.

They used to time E* like this, but since phase 1 of the CTRL opened this
pairing of departures has been the exception rather than the rule. There
was
apparently a problem at Waterloo International with trying to load up to
1500 passengers on to two trains on opposite sides of an island platform -
congestion and the risk of sending Brussels passengers to Paris and vv. In
the current timetable the only paired departures seem to be:
0629 Paris/0634 Brussels
1039 Paris/1042 Brussels
1909FO Paris/1912 Brussels
1034Su Paris/1037Su Brussels.
Peter


Several end up being paired by the time they arrive at the tunnel, due to
one having stopped at Ashford.
Brian

Arthur Figgis ] wrote in message . ..
[1]I can't imagine many people would commute /from/ Heathrow, owing to
a lack of housing near the airport stations?

Actually, commuting from Gatwick has more to do with plentiful
convenient parking and frequent services than anything else. Call it
'Gatwick Parkway' if you will. An ex-colleague of mine used to live
somewhere near East Grinstead, and park-and-ride from Gatwick was the
easiest way to get to work in London.

In the case of Heathrow, there are more options for park-and-ride, and
indeed more options for using other stations as railheads for a
commute -- usually at much less cost. Plus I'd guess that with
Heathrow being more hemmed in and more prestigious, parking would be
rather more expensive. I'd believe that a few people who live in the
Staines direction and work in the Paddington area might park-and-ride
from T4 though -- and if T5 gets decent parking with direct access off
the M25, it might spur significant park-and-ride.

"Peter Masson" wrote in message ...
"Graeme Wall" wrote in message
...

Good point - especially valid if they run the Eurostars in pairs, one
to Brussels and one to Paris.

They already do, the two services depart Waterloo 5 minutes apart, all to
do
with paths through the Channel Tunnel. IIRC one Eurostar requires two
shuttle paths but a 'flight' of two Eurostars only requires 3 paths, thus
saving a path that Eurotunnel can use either for shuttles or freight.
This
obviously has the same effect on the CTRL: 2 fast trains close together,
then
the next two 25 minutes later, should be fairly easy to flight the slower
trains in the resulting gaps.

They used to time E* like this, but since phase 1 of the CTRL opened this
pairing of departures has been the exception rather than the rule. There was
apparently a problem at Waterloo International with trying to load up to
1500 passengers on to two trains on opposite sides of an island platform -
congestion and the risk of sending Brussels passengers to Paris and vv.

I hope they learn for the St Pancras design.

It's not often that Eurostar trains have 750 passengers on them.

"Bob" wrote in message ...


It's about 70 miles St Pancras to the tunnel, so:

180 mph = 23 min
160 mph = 26 min
150 mph = 28 min
140 mph = 30 min
90 mph = 47 min

Trains running at 140 mph adds only 5 min, but makes the commuter
problem much, much easier.

(Velocities are max, I know average speeds will be less, but the logic
is the same).

In my world, 30-23 is 7 not 5.

Sorry - but anyway, St Pancras to Ebbsfleet, and the North Downs
tunnel, speeds will be limited by tunnel design. Assuming the same
acceleration, a train desinged for 140 mph would only be a few minutes
behind a 186 mph train by the time they get to Ashford.

As pointed out elesewhere, this is well within the frequency
requirements of the line, especially after Ebbsfleet.


Anyway, the point of the line is to cut as much as possible off the journey
time between London and Paris / Brussels. Running trains at 186mph is the
plan - your commuter trains at 140mph would get in the way.

Since the technology exists for 186mph running, why not just build the damn
trains instead of messing things up with a stupid fudge. Your kind of
thinking is why things always turn to crap in this country.