"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).