Tom Anderson wrote:
On Thu, 26 Apr 2007, Dustbin wrote:

You cannot build tunnels across continental plates.

A Bering Strait bridge is the answer; one platter can rest upon
rollers with each end on different continents. It would still
require good maintenance and the platter would have to be replaced
regularly but it is not impossible.

How do you interface the track running across it at the ends, though?

http://commons.wikimedia.org/wiki/Im...b_ExpJoint.jpg

Or... the track leaves the platter sideways. When the platter moves, the
track moves sideways (similar to points) but doesn't have to change length.