"Alternative 1" was a plan to blast holes through the stratosphere to release heat and pollution. "Alternative 2" was a plan to relocate Earth's population in massive underground caverns drawing fresh, cool air from the soil (Perhaps there is a real Alternative 2 in progress).
A tunnel is an underground passageway, dug through the surrounding soil/earth/rock and enclosed except for entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods.
Exposure to respirable crystalline silica dust during construction activities can cause serious or fatal respiratory disease. The National Institute for Occupational Safety and Health (NIOSH) requests assistance in preventing silicosis and deaths in construction workers exposed to respirable ...
Practical Tunnel Construction [Gary B. Hemphill] on . *FREE* shipping on qualifying offers. The only modern guide to all aspects of practical tunnelconstruction Practical Tunnel Construction</i> fills a void in theliterature for a practical guide to tunnel construction.