Volume 7, no. 13 - Colbond Geosynthetics

Will bypass bring
mountain idyll back
to Giswil?
10 Colbond Geosynthetics News 13 - 2002
Past Oerlikon Stadium, the highway south pops in
and out of the shade of a seemingly endless series
of cut and cover tunnels, then stretches out along a
chain of long lakes mirroring the rocky peaks
around. It’s the stuff picture postcards are made of.
For the good people of the town of Giswil,
Switzerland, however, peace and quiet may only now
be returning. For this town of not quite 3,500 souls is
located on the main arterial road between the
metropolis of Zurich and the city of Interlaken.
Convenient enough for the tens of thousands of
visitors who come each winter to ski on the
surrounding 6,000-foot slopes, but something less
than a blessing for the citizens themselves.
The beginning of the solution started,
however, when the authorities of
Obwalden Canton received approval
to build a two-kilometer bypass tunnel
to lead the N8 national highway
around Giswil. The project, estimated
at some 121 million Swiss francs,
started in 1997 and is scheduled to
be open to traffic in the course of
2003.
Although the tunnel is not yet open to
the public, construction machinery
now drives in and out of the south
portal, where the first breakthrough
came in February of 2000. Inside, the
tunnel itself is a model of modern
engineering. When completed, the
inner shell, with a diameter of a little
over ten meters, will house a twolane
highway with a maximum speed
limit of some 85 kilometers an hour
and a gradient of 2.5%. To get there,
the builders used more than 50,000
man-hours and 180 tons of
explosives to mine their way through
sandstone, chalk and limestone
formations. Close to the north portal,
the almost vertical layers of
sedimentary rock produce a flow of a
few hundred liters of water per minute
in the vicinity of the tunnel entrance.