"Robert Woolley" wrote in message
...

The cost of the tunnel is going to be quite closely
correleated to its size. The bigger the tunnel,
the more spoil to remove and the tighter the engineering.

In particular, if you make the radius 40% larger you have twice the spoil to
remove.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes