What sets the speed in CTRL tunnels through London?

On Sep 5, 11:06 am, Michael Bell <mich...@beaverbell.co.uk> wrote:

>>> Eurostars go through Kent at 180 mph, so we are told. Then they slow
>>> down to 140 mph in the CTRL tunnels in London. Why?

As I have remarked before in this forum, the speed through the Channel
Tunnel was reduced from its originally proposed value. One (of several)
reasons was the effect of the pressure pulse on equipment cabinets in the
tunnel, which are sealed but full of air and therefore flex inwards ahead
of a train and outwards behind it. Slowing the trains a little meant that
cheaper cabinets could be used.

I don't know whether that's (part of) the reason for the speed reduction in
the CTRL tunnels, but it is a general consideration for rail tunnels, not
just for cabinets but for anything moveable or bendable.

Peter

--
Peter Campbell Smith ~ London ~ pjcs00 (a)