Tunnel work on track
By Lindsay Gale12 March 2008
The Gotthard tunnel was opened in 1882 and forms part of one of the world's more spectacular travel routes. The railway line winds its way through the Swiss Alps through a series of helical tunnels to the entrance of the tunnel.
A concrete tunnel bridge spans a 50 m (166 ft) valley on the route, but is exposed to avalanche. Recent tests indicated that the 88.5 m (290 ft) long bridge could have been swept away with the next avalanche winds. A study found that the bridge and tunnel should be reinforced, the bridge pilings restored, cracks up to 2 m (6.6 ft) deep refurbished and that the tunnel bridge should be connected to special wall anchors.
Hydrodemolition specialist Brugger was awarded the contract to remove 230 m2 (2,475 ft2) of concrete using the latest generation Aquacutter Evolution robot. The machine, operating at an altitude of 1,300 m (4,500 ft) was lifted into position by crane and installed on the opposite side of the valley.
In order to cut 20 mm (0.8 in) on the outside tunnel wall, an additional 5.5m (17.8 ft) was added to the Aquajet's standard 6 m (19.4 ft) tower and the machine angled to match the 10 degree inclination of the tunnel wall using a special support.