Volume 7, no. 13 - Colbond Geosynthetics

Forces at play
Fire safety is a very important
parameter in tunnel construction.
Today’s tunnel materials are therefore
subject to very stringent fireproofing
requirements. But the very makeup of
the Earth’s crust through which these
transport tubes are bored or blasted,
and the forces at play in those layers
of rock, pose hazards and challenges
all their own. A perfect example is
found in one of the biggest tunnel
ventures ever: the NEAT (New Alpine
Rail Axes) project.
Being billed even now, in the first
years of the new millennium, as “the
rail-transport project of the century”,
the NEAT plan is being supervised by
Switzerland’s AlpTransit authorities
and is breathtakingly ambitious.
Consisting of two gigantic and
roughly parallel base tunnels, the
Lötschberg and the Gotthard, NEAT
will create new high-performance rail
links on the north-south axes through
Switzerland. Among other things, the
project is creating the world’s longest
rail tunnel for passenger and goods
transit traffic - 57 kilometers from
Erstfeld in central Switzerland to
Bodio in the Italian-speaking south.
This section alone, scheduled for
completion in 2012, is expected to
cost more than 10 billion Swiss francs
(US $5.8 billion).
That the art of tunneling today has a
pronounced high-tech element is
illustrated by AlpTransit’s use of GPS
satellite communication, in
combination with gyroscopic (nonmagnetic)
compasses and computer
simulation, to guide surveyors
working at the mountains’ heart.
Because tunnels of this length must
be built in stages, often starting at
points dozens of kilometers from
each others, pinpoint navigation is
essential. Still, many were amazed
when the Swiss authorities recently
announced that the current state of
alignment between the portals at the
north and south ends of the 57kilometer
Gotthard Base Tunnel had
achieved an accuracy of less than
one centimeter!
Cover story
Soaring demands
With the extension of its railway
infrastructure, and the use of highspeed
freight and passenger trains,
Switzerland plans to be in a position
to meet soaring demands on its
international transport grid. A study
recently carried out on behalf of the
European Commission showed that
by 2010, this traffic through
Switzerland will have increased by
around 75% above 1992 levels. One
goal of the NEAT project, therefore, is
ultimately to almost halve transport
times from north to south - estimates
are that, by the time the project is
completed, travel times for passenger
trains from Zurich to Milan will have
shrunk from three hours and forty
minutes today to a mere two hours
and ten minutes.
But even more amazing than length,
expense or speed, perhaps, is the
depth at which the tunnels in the
NEAT project are being built.
Because the tunnels are being bored
and blasted much closer to the base
of mountains than ever attempted
before (at the most extreme point,
there will be more than 2,000 meters
Colbond Geosynthetics News 13 - 2002
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