The Race Underground is based in part on a book of ... still uses some of the original tunnels today. Like so many things built in the past, they’re small, and narrow enough that longer trains ...

The surrounding rock may become unstable or even fall down and the initial support may crack and be destroyed when the construction method of the underground excavation tunnel is not properly ...

U.S. and South Korean troops honed their underground combat skills using drones and breaching tools as part of a recent large ...

In addition to the tunnel, medium-size underground rooms were also detected at a second subterranean level, she added. Researchers suspect that there are more subsurface structures to be uncovered ...