Engineering Inc. - November/December 2019 - 15

"Tunnels are now being constructed
through conditions that would
not have been contemplated over
20 to 30 years ago."

and is the widest in the world at nearly 58
feet. The project won the ACEC 2019 EEA
Grand Conceptor Award for the year's most
outstanding engineering achievement.
Make no mistake, planning, designing,
and constructing tunnels frequently push
engineering, especially geoengineering, to its
COLIN LAWRENCE limits. It requires both creative thinking and
GLOBAL TUNNELS PRACTICE LEADER technical expertise.
MOTT MACDONALD
"In the past, you had someone with a
vision of how to build a tunnel, and they
and a small group of engineers spent a
nel, connecting New York and New Jersey,
whole bunch of time figuring it out," says
was built. It represented a tunneling landGlen Frank, senior vice president of undermark. As vehicles passed under the Hudson
ground construction at Schnabel EngineerRiver, 84 fans housed in four buildings
ing. "Today with CAD and BIM, you can
changed the tunnel's air every 90 seconds.
experiment with different shapes, forms,
Over the last 30 years, advances in geoand structures-and understand how to
science, technology, and construction have
design tunnels so they work with compliallowed engineers to extend tunnels to places
cated underground transit stations or other
that once seemed unimaginable. For examinfrastructure."
ple in 1988, Japan built the 33-mile Seikan
Nevertheless, it may take two decades or
Tunnel, then the world's longest and deepest
longer for a tunnel to leap from the drawing
railway tunnel. It reaches a maximum depth
board to reality. During that time, things
of 787 feet beneath the surface and conchange. For instance in the future, internects the cities of Honshu and Hokkaido. In
nal combustion engines could be largely
1994, the U.K. and France opened "The Chunnel" a $21 billion replaced by electric vehicles that do not require the same heat
project that allowed trains to pass under the English Channel.
removal and ventilation system in a tunnel.
Completed in 2019, the Alaskan Way Viaduct Replacement
"One thing that makes the planning task difficult is that
Program is a 2-mile tunnel that carries a 1.7-mile, double-deck
when you have a 15- or 20-year lead time on a large transportahighway. It is more than 200 feet beneath downtown Seattle,
tion tunnel, by the time you actually complete building it, the

Depending
on the type of
tunnel, tunnel
boring machine
costs can range
from approximately
$10,000 to
$100,000 or
more per linear foot

MOTT MACDONALD

A tunnel boring machine
makes breakout for the
Arrowhead West Tunnel, a
water supply tunnel built by
Metropolitan Water District
of Southern California. Mott
MacDonald designed and
developed probe drilling
projection computer models
and an early warning
detection system to monitor
strain on the shields of the
tunnel boring machines.

NOVEMBER / DECEMBER 2019

ENGINEERING INC.

Engineering Inc. - November/December 2019

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