International contractors to bid for twin span suspension structure.
More than 45 international contractors have expressed interest in taking on construction of a 2.6km long triple tower suspension bridge across the Chacao Channel in southern Chile.
The Chilean government restarted the tender process for the project last year, six years after soaring costs forced officials to shelve it.
The inhospitable environment in which the bridge must be constructed was part of the reason for the cost escalation. High intensity earthquakes are common in the area and contractors would have to contend with very strong water currents of up to 1.9m/s. The geology is also challenging.
The 2,635m long bridge was one of several projects planned to commemorate Chile’s bicentennial in 2010 but it was suspended when costs soared by $300M (£190M) to £590M.
Design, build, finance, operation and maintenance was originally to have been carried out by Consorcio Puente Chiloé (CPC), a joint venture between Hochtief, Vinci, American Bridge and local firms Empresa Constructora, Tecsa and Besalco.
The revived plans are for a lump sum design and build project, with the budget capped at £470M.
Flint & Neill was CPC’s independent engineer on the original project. With United States consultant Ammann & Whitney it supported design work carried out by its now Danish parent Cowi. The same team has united to work on the new proposals.
The original plan was for a continuous suspended steel box girder structure with one main span of 1,100m and one of 1,055m.
A key feature of the bridge was its A-shaped central pylon, founded on piles bored into a layer of submerged rock known as the Roca Remolinos.
The geology of this rock and the strong currents around it present particular design and construction challenges.
Client Chile’s Ministry of Public Works has specified that the crossing must still be a suspension bridge with principal spans of at least 1,000m. It also said the bridge would “preferably” carry four traffic lanes in each direction, but that three could be acceptable.
It believes that the new procurement approach combined with technical advances in long span suspension bridge design since 2007 mean that the bridge can be built at a lower price.
Prequalification applications must be made next month. Detailed tenders will be invited in March, with nine months allowed for submissions.
The contract is set to be awarded in the first quarter of 2014 with the start of construction due in 2015.
The aim is to have the project completed by 2019.