Construction of the first Ulriken tunnel, approximately 7.8 km long, began in the mid-1950s and was part of the construction project for the Bergen to Voss railway line in Norway. The construction of the tunnel was a challenge due to the region’s mountainous topography and changing geological conditions. It was inaugurated in 1964. Over time, it became one of the most congested tunnels in Europe. The objective of this contract is to improve the waterproofing of seepages and the rail connection between the existing tunnel and the new tunnel by installing two diagonals. To carry out the waterproofing, the tunnel section was widened in several sections, bolts were installed and concrete was sprayed. The waterproofing solution includes a PVC and Foam membrane, with a cavity in the backside to protect against freezing phenomena. The support of the new excavated section of the tunnel includes bolting and shotcreting. The works were divided into the following areas: This contract also includes the construction of a new railway bridge in the Bergen area, as well as the development of the streets and the construction of a car park for the nearby residential buildings. Sound barriers were installed on the railway bridge. Inside the old tunnel, the renovation operations included blasting with explosives for the transverse and diagonal galleries. The main challenge was to excavate approximately 50,000 m3 of rock by blasting in a single-track tunnel without causing accidents to workers, nearby houses or rail traffic in the parallel tunnel. Another major challenge was equipment logistics due to the limited space in a small tunnel section, where several activities were carried out simultaneously. Arna Bergen Railway | Renovation of the old Ulriken tunnel
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