Photo of the prefabricated tunnel segment models
(click image for larger detail.)
This is an HO scale model of a alternative pipe-shaped tunnel segment.
It is an alternate option to the arch-shaped reinforced tunnels.
It would be fabricated from a a strong steel alloy, that is corrosion resistant,
such as HY-80 steel.
It would be manufactured from extruded rings that are welded together, a total distance
of approximately five miles.
The interior could be lined with an insulating material, such as the silicon fiber
heat tile material used in the space shuttle.
Potential Tunnel Design Shapes