Construction of a trans-Alpine railway tunnel some 24km long linking Briançon in France and Oulx in Italy is currently being considered by local government body, the Provincial Administration of Turin.
Italian-French consultant JV Geodata-Setec-ATS has submitted a feasibility study sponsored by the administration that will serve as a basis for the decisionprocesses at European level.
The study has identified two main corridors for the ambitious project. The first, at 23.9km, runs from the Oulx plain in Italy parallel to the Dora Riparia River towards Cesana-Briançon. The second, at 22km long, starts further upstream in the Dora of Bardonecchia Valley near Beaulard and onto Briançon.
The configuration envisaged is a single bore, single track tunnel with an enlarged zone for interchange. This is a safety-lead decision to reduce head on collision chances and increase ventilation efficiency.
The JV has used the DAT program (Decision Aids in Tunnelling) that enables estimation of tunnel construction time and relative cost in areas of high geological and geotechnical uncertainty. Three construction alternatives were analysed. These were traditional drill and blast of the complete length, TBM drives or a mixed approach. Results predict that the cheapest yet longest schedule method would be two TBM drives with a cost factor of 1 and four year duration. Second was the mixed approach of five drill+blast advances and one TBM. This was faster with a contract duration of around three and a half years but more expensive with a cost factor of 1.2. Finally the eight drill+blast advances produced the best schedule of just over three years but was more expensive again with a cost factor of 1.3.
The tunnel is planned to increase links between Italy and France for passenger trains, cargo trains and mixed road and rail services with a forecast traffic level of some 100 trains per day.
Related Files
Map
Two tunnel route
