This 755 meter long tunnel has been in service for over a week, in the direction of Italy. The point of this diversion is to move the traffic away from the landslide, and is going to cost 60 million EUR.
The regular commuters of the A8 highway have probably been surprised with the new 3 lane modifications that were put into place yesterday morning. The tunnel La Borne Romaine which is part of the commune of La Turbie, was opened to traffic. 3 lanes for those heading towards Italy and 1 lane for those going towards Aix-en-Provence. The reason for all this big traffic re-routing, is the geological instability of the terrain between the 2 toll gates of Nice-Est and La Turbie.
The civil engineering company Vinci Autoroutes, has had to step up the game, and took on this massive project since spring 2014 for 3 years of work, and they opened earlier than expected.
It was a very tough job as they had to rehabilitate the flanks of the cliffs with wire meshing to hold the rocks into place, avoiding possible landslides. Various engineering techniques were used to be able to dig the tunnel, pump in vast amounts of concrete and reinforce the unstable terrain. 100.000m² of excavation were manipulated on this site. The whole project was as big as 12 Labours of Hercules.
The difficulty was ensuring that the whole project would be compliant to the very strict health safety agenda. Amongst the security issues addressed in the tunnel for the safety of the future motorists, were the installation of 80 LED lights, 20 CCTV Cameras (of which 13 can automatically detect an accident), and the latest SOS stations.
The tunnel measures 755 metres long, 12 metres wide, 5 metres in height, 36 kilometres of cables, and the whole project on a 5.2% gradient. Once again the French Engineering has proven that it can tackle the most daunting projects in the most efficient manner, delivering the best quality workmanship in the world.