Final lining work is underway in the twin bore San Cristóbal road tunnel being built by a Hochtief JV in Santiago, Chile, on a PPP project that saw breakthroughs a few months ago.
Excavation of the twin two-lane tunnels started in April 2006, a few months after the late 2005 commencement of construction which was delayed due to a realignment of the north portal. The contractor excavated the 1.8km long drives, and eight evacuation galleries (two for traffic, the rest for pedestrians) spaced 200m apart, by both drill and blast and mechanical excavation, the tubes being holed through in March and April, respectively.
The drives were advanced through full face excavation from both ends in each tunnel, employing two daily shifts. Excavation was completed within the contractual milestones and progress rates of approximately 4m/day was achieved through porphorytic andesite and andesite. There were little problems of fractures or groundwater, the contractor told T&TI.
Equipment used on the drives were a pair of Tamrock Axera T111 Jumbos, a Tamrock Paramatic H-205 Jumbo and four Caterpillar excavators (pairs of 320CU and 330 CMLE). Additional plant on the drives included two Broyt loaders (D600W and ED600W), plus ORU Marte shotcreting plant.
The support and primary lining of the 10m wide (75m2) bores was shotcrete with fibre and rock anchors, lattice girders and spiling where necessary. The secondary lining consists of shotcrete with synthetic fibre plus waterproof membrane, as required. Work is expected to be completed in August.
Before the scheduled opening of June 2008, the remaining work includes installation of M&E services, including longitudinal ventilation, signalling, emergency protection and electronic tolling. The US$95M automatic toll tunnel and access roads project is being built to link the capital’s business district with the Vespucio Ring in the northern part of the city, and the Kennedy Highway to the east.
The PPP concession was tendered in September 2004 and awarded in 2005 by the Ministry of Public Works to a JV of Hochtief and ACS-Dragados as a design, finance, build and operate contract. For the construction element, the design and build contract is being executed by Madrid-based consultant Geocontrol, and the construction partners on the project are Hochtief, Dragados, Brotec and Belfi.
Following the construction phase of the 4.1km link, the concession company will have the remaining 30 years of the concession – to 2038 – to operate the toll link. The project also includes construction of 2.2km of urban roads.
Hochtief AG The Hochtief JV is completing the San Cristobal tunnel, in Chile The Hochtief JV
