Blasting explosives like gunpowder, nitroglycerin, and dynamite all work well for carving a tunnel through a mountain. The dense rock walls can support themselves, and they won't collapse into the ...

Tunnel shields are built to slice through soft soil, like sand, clay, and silt. They're not strong enough to carve through a mountain of rock. In order to bore into this mountain, you need a ...

The sight of a passenger train or coal train rumbling through the west end of the Moffat Tunnel at Winter Park Resort is a ...