Roveredo Bypass: Tunnel Breakthrough

A 2-lane bi-directional tunnel is being built for the Roveredo Bypass – with shoulders at both sides and 2 lay-bys. It has up to 3,000 m overburden and runs north with 0.8 % gradient lying in an arc with a radius of more than 1,000 m. It is roughly 2.6 km long and possesses an equally long evacuation and rescue tunnel with 7 cross-passages, 2 of which are accessible with vehicles from the 2 lay-bys. If required, this heading is to be developed as a second, 2-lane tunnel bore with directional traffic. Controllable flaps are set up at 100 m gaps in the intermediate ceiling above the 11.5/18.0 m wide and 11 m high carriageway connected to the ventilation control centre at the south portal to remove smoke in the event of fire in the tunnel. The construction activities on the Roveredo Tunnel began on the rise with an exploratory heading in the tunnel axis from the south portal. The 4 m cutterhead diameter tunnel boring machine that was applied then tackled the parallel evacuation and rescue tunnel – with the rock being secured in both structures with shotcrete and in part with rock anchors. Some 2,100 m of tunnel was excavated (roughly 400 m of tunnel has been produced by cut-and-cover) after only 21 months by drill+blast thanks to the deployment of a novel drilling jumbo (with 3 drilling arms and a loading basket). After installing the seal, 2 formwork cars were applied to build the inner shell with up to 2.5 kg PP fibres/m³ being added to the concrete for fire protection purposes.
Work commenced in April 2009 at the south portal and the tunnel bore was broken through in November 2012. The rough construction operations are due to be concluded in 2014 and the tunnel is scheduled to be opened as part of national highway N13 in 2016. 120 million CHF (roughly 100 million €) has been earmarked for building the project.⇥G.B.