The work and the technique: Fréjus highway tunnel, Italy and France

Works to build the Frejus highway tunnel began on January 20, 1975, a century after inaugurating the historical railway tunnel.
If the railway tunnel saw one of the first uses of pressurized air for ventilation and the activation of the excavation equipment, the new work represented the first application for a tunnel of such length of the electro-hydraulic boring technique that could improve both execution times and the environmental conditions of the construction site. The Jumbo was specifically created for this purpose: a gigantic tunnel jumbo drilling rig that was completely automated.  With over 23 metres in length, 9 m in width and with 6 hydraulic drilling arms mounted on skids, the Jumbo allowed a high average advancement (7.50 metres per day), reducing work times and preserving the safety of all the workers involved in the project.

Other innovative techniques included removing waste material, managed by a dumper and an electric power shovel to reduce pollution; the use of a trench profile control wagon and calculating the concrete needed for the lining and an automated-dosing concrete mixing plant with a vapour heating plant for allowing to carry out concrete jets in the tunnel with temperatures lower than - 20°C.