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APRIL 2009 FEATURE STORIES:
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Going the Distance
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Tunnel Ventilation
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Tunnel Shafts in the Greater Toronto Area
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Microtunneling on Maui
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Today’s hard rock TBMs are highly capable, specialized machines designed for any number of ground conditions, from a fractured, mixed face to the highly stressed rock beneath an 8,000 ft high mountain. But what makes a TBM great? From setting world records for speed to boring 25-plus miles, the answer is anything but straightforward. 
Atunnel ventilation system is basically a system that imparts energy to the air with fans to produce a given velocity and pressure. The air is forced through a long duct that soaks up the energy with friction. The excess energy delivers a quantity of air to the heading. For a given length and type of duct, three major factors determine how much energy is required to move the air: volume of air being moved; duct cross-sectional area; and the length of the duct. 
It is often rather amusing to hear the mumbled words uttered from someone once they gaze down into deep shaft for the first time. Many would view such an excavation as a “deep hole in the ground,” but to the tunnelling professional it is much more than that. Suitably designed tunnel shafts, access ramps or portals are vital to enable successful tunnel construction.
Forget about hula skirts, trade winds, surfing and Aloha hospitality. This is all about the infrastructure that enables our 50th state to serve its residents and tourists. 
PAST EDITIONS OF TUNNEL BUSINESS MAGAZINE |
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