Contractors Acciona and Ghella have completed the excavation works of the twin 19.5km long, 8.8m diameter railway tunnels for the Follo Line project between Oslo and Ski in Norway. The two TBMs of the four that the Acciona-Ghella Joint Venture (AGJV) has used on this project, reached the town of Ski on Tuesday 26 February, completing the TBM drilling work. The other two TBMs completed their work in September last year.
The four 9.9m diameter Herrenknecht machines, each 150m long and weighing 2,400 tonnes, started out from the same point in the Norwegian district of Asland, from where two of them drilled south towards Ski, and the other two drilled north towards Oslo.
One of the greatest challenges for the project has been the extremely hard rock, which has made drilling work difficult, combined with ground weakness in other zones.
“AGJV has worked extremely hard of which we are proud, delivering quality, safety, innovation and experience. We have excavated more than 18 kilometres of tunnel and have delivered them on time, fulfilling our commitment. We have faced important challenges related to the ground conditions drilling towards Ski and we feel proud to be part of such a demanding TBM project. We are now entering a new phase, confident that we will once again do an excellent job”, said AGJV project manager, Fernando Vara.
Once the excavation work of the tunnels has been completed, AGJV will carry out all the railway installation works, except for the signalling systems. The planning phase for these activities has already begun and the concreting works, the preparation of the tunnel walls and the catenary systems, and the walkways and the technical rooms will all be carried out in the coming months. The telecommunications systems, installation of the tracks and the power supply and ventilation systems also form part of this project.
The Follo Line is the largest transport project carried out in Norway to date. It is part of the wider inter-city development plan for south-east Oslo, which seeks to improve and develop the country’s transport infrastructures and is due to be completed by December 2021.