Colombia Completes La Linea Exploration TunnelThe last blast of dynamite that pulled down the last chunk of rock in the La Linea pilot tunnel on 2nd August, 2008 was preceded and followed by cheers of joy, congratulations and even the emotion of singing the national anthem by the two teams of workers who finally joined the two sides of the tunnel, 800 metres under the mountain. To achieve this objective, between 370 and 500 people worked 24 hours in several shifts for 1,294 days. In total, 8,542 metres of tunnel, 4.5 m in diameter, was constructed. The total investment of the pilot tunnel amounts to COP109,813 million.On 4th August, Colombian president Alvaro Uribe and minister for transport Andres Uriel Gallego inaugurated officially the pilot tunnel pulling down with a pick axe a symbolic polystyrene and concrete wall materialising the junction of the two faces.Pilot tunnelLocal authorities decided the construction of the 8,554.50 m La Linea exploration tunnel between the municipalities of Calarca and Cajamarca, in the eastern central part of the country, with the objective to survey the geological conditions. The aim is to know the geological composition of the central Andes and map the hydrogeology and geotechnics to optimize the construction of the final tunnel.Throughout the construction of the pilot tunnel, crews encountered four geological faults in places named La Cristalina (33 metres) and La Soledad (480 metres), which required additional excavation and special concrete reinforcement. The other two faults, Alaska and another at 1,710 metres, were found by the crew working from the Galicia portal, but they were very short. Nevertheless, these four faults do not represent major difficulties for the main tunnel.In addition to serve as reference to know the geological conditions of the ground, the pilot tunnel will also be used for emergency and ventilation when the main tunnel opens. Click here.The tunnel forms part of a series of projects aimed at easing traffic between Buenaventura and Bogota, which includes the construction of the main tunnel and a second carriageway between Calarca and Cajamarca, amongst other things. This includes in particular the construction of four bridges and three more tunnels: Estrella (326.50 m, completed in October 2007), Robles (805.40 m, 96% completed) and Los Chorros (206.50 m, 34% completed).Main tunnelThe La Linea tunnel will be renamed Segundo centenario tunnel. The pilot bore will be commissioned to the constructors who will be awarded the contract to build the main tunnel as part of the second phase of the project, which will have to be completed in less than 70 months, i.e. 2014. The national highway institute Invías will close the tender for the construction of the main tunnel on 15th September and hopes to receive five bids. During the bidding process, 171 national and international contractors have been registered. There are companies from Argentina, Brazil, China, Colombia (in particular Conconcreto, Odinsa and Solarte), Iran, Italy, Korea, Mexico and Spain competing for the project. The contract is expected to be awarded in October, with work commencing at the end of the year or in early 2009. The initial budget to build this project totals COP719 billion. This figure includes the main tunnel and the second carriageway between e Calarca and Cajamarca. Click here and co/15. Visit www.invias.gov.co and www.calarca.net/tuneldelalinea.html 34-35/08.