Perthus launched across Pyrenees

12 September 2005

As part of the Figueras – Perpignan high speed rail line across the Pyrenees, construction was officially launched for the 8.3km long Perthus tunnel (T&TI, June 2003, p6) on 19 July at a ceremony featuring dignitaries from the Spanish and French governments.

The twin tube tunnel is the biggest individual structure within the scope of the new link and was described to T&TI by a member of the TP Ferro contractor consortium as "the biggest construction challenge and the most important construction work" on the project. TP Ferro was awarded the concession to design, build and operate the high speed link in a joint accord signed by France and Spain in December 2003. Two months later, on 17 February 2004, the final contract between TP Ferro and the two states was agreed.

TP Ferro is formed by a 50:50 partnership between Spain's ACS Dragados and france's Eiffage, plus strategic associations. The 8.5m i.d. tunnel is made up of twin tubes excavated by TBM with 41 cross passages at 200m centres. Additionally, there will also be four equipment galleries at 1.6km centres. A source told T&TI how the spacing between the twin tubes varies between 25-35m, with each having a "useful" section of 50m2.

Two Herrenknecht hard rock double shield TBMs will be used to drive the running tunnels from the Spanish portals. With an o.d. of 9.96m, the TBMs will install a precast concrete segmental lining, consisting of six segments plus a key per ring, as they advance. The geology expected consists of granite, granodiorite, gneiss, schists, mylorite and diorite. Muck transport will be by conveyor to the portals. Of the US$1.18bn project cost, US$375M is allocated for the tunnel, with US$223M and US$156M for the French and Spanish surface works respectively.

The project source told T&TI that safety features within the tunnel include the cross passages, ventilation, fire detection and suppression systems; dual power supplies; safety gear at both portals and designated access for emergency teams and a heliport. Measures for line safety include falling object detection, wheel flat spots, high pantograph and clearance detection systems.The new line enables interoperability of qualifying trains from either Spanish or French network without distinction.