Lyon-Turin base rail link preparatory works award 16 Jul 2020

Armand van Wijck, TunnelTalk Europe correspondent

A €220 million preparatory works contract is awarded by the French-Italian project developer Tunnel Euralpin Lyon Turin (TELT) to start of construction for the 57.5km long Mont Cenis base tunnel. Awarded to a consortium led by Vinci with Dodin Campenon Bernard, Bergteamet and Salini Impregilo (now renamed Webuild), the contract encompasses works needed to prepare for excavation of the main base tunnel Lot L1 of the 21.9km of twin tube alignment on the French side of the bi-national project between Villarodin-Bourget and Modane (Fig 1 and Table 1).

Fig 1. Base tunnel design and main excavation drives
Fig 1. Base tunnel design and main excavation drives

At the end of the Summer the consortium will start work with excavation of four ventilation shafts from the Villarodin-Bourget-Modane access tunnel. The 500m deep x 5.2m diameter shafts will be excavated as raise bores. Also in the contract is excavation of seven caverns of up to 22m high x 23m wide that will be used also for assembly of TBMs that will excavate the base running tunnels towards Italy. The preparatory works contact has a 36-month period and will employ up to 250 workers and managers.

Activities will continue simultaneously on six other operational construction sites.

Table 1. Contracts for the main construction lots
L3 Base Tunnel - France
Section Villard – Clément
Value €180 million
Length 1.4km adit and 4km adit
Construction time 98 months
L2 Base Tunnel - France
Section La Praz – Saint-Martin-La-Porte
Value €1.13 billion
Length 23.1km twin tunnels
Construction time 98 months
L1 Base Tunnel - France
Section Villarodin-Bourget – Modane
Value €1 billion
Length 21.9km twin tunnels
Construction time 102 months
L1 Base Tunnel - Italy
Section Chiomonte – Susa
Value €800 million
Length 12.5km twin tunnels
Construction time 108 months

In France, at Saint-Julien-Montdenis, a consortium led by Bouygues is close to completing a cut-and-cover approach tunnel for the base tunnel portal. The cover-slab, to be completed by the end of Summer 2020, will support the existing motorway that will move back to its initial location in Autumn.

At the Saint-Martin-la-Porte adit, a consortium led by Spie Batignolles is continuing open face excavation through the weakest geological zone of the entire project alignment. From the same adit, the consortium is completing disassembly of the first TBM used on the base tunnel project. The 11.25m diameter NFM TBM launched in 2016 to excavate the south tube of the main running tunnels from Saint-Martin-La-Porte to the La Praz access adit. The hard rock single shield TBM is the first of eight TBMs to be used on the project and completed its 9km long drive as a geological exploratory heading. The parallel running tunnel will be excavated as part of the main base tunnel Lot 2 contract that is currently in procurement.

In Italy, the La Maddalena construction site is being prepared for future base tunnel excavation by a group led by Webuild. The surface area of the construction site has been extended by about one hectare, with fences and a bridge installed for site traffic across the Clarea River.

According to TELT, the call for tenders for excavation of the main base tunnels is progressing (Table 1). Companies have submitted bids for the three main tunnel construction lots with a total value of €2.3 billion on the French side. Contracts are to be awarded by the end of the year. Procurement has also been set in motion for award of the 12.5km section of the base tunnel worth €1 billion on the Italian side. These contracts will be awarded at the beginning of 2021.


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