Arna-Bergen railway line – Railway technology


The Norwegian company Bane NOR is transforming the Arna-Bergen single-track railway line into a double-track line. Image courtesy of STRABAG.

Construction of the new 7.8 km underground tunnel at Ulriken began in 2014. Image courtesy of Bane NOR.

The Skanska and Strabag joint venture successfully completed the Ulriken Tunnel in August 2017. Image courtesy of Bane NOR.

Arna station is being renovated to accommodate double tracks. Image courtesy of Norconsult.

arna-bergen line

The Arna-Bergen single-track railway line in Norway is being converted to double-track to facilitate increased speed and more flexible traffic flow.

The project also includes the construction of a new 7.8 km underground tunnel in Ulriken and various modernization works at Arna station.

Construction of the project began in 2014 and the dual carriageway will enter service from 2022.

Tunneling work began at Arna in January 2016, while breakthrough was achieved at Fløen on August 29, 2017.

The project is being developed by the Norwegian state company Bane NOR, which is responsible for providing the national railway infrastructure in the country.

Details of the Arna-Bergen railway line

The Arna to Bergen line double track initiative will be split into two segments for construction purposes, with the project work split between the Arna to Fløen and Bergen to Fløen routes.

The Arna to Fløen segment includes the construction of a new parallel tunnel between Arna and Fløen (Ulriken), as well as the modernization of the old tunnel, the modernization of Arna station and other technical improvements.

Major works on the Arna-Fløen line include the construction of a new 11 km overhead contact line system, a new lighting and interlocking system and upgrades to the earthing installation .

The project will also see the supply of an interface with the Arna converter station in order to supply the overhead contact line.

The Fløen to Bergen segment includes the construction of a 1.3 km double track, the installation of a new Class B interlocking system in Bergen and other technical improvements.

The new interlocking system of the Bergen station will also be able to control the Arna station.

Other works along this segment include upgrades to the track substructure, including drainage systems, cable ducts and ballast installations.

Ulriken tunnel construction

Traditional blasting was used in addition to tunnel boring machines to dig the new Ulriken Tunnel, making it the first railway tunnel in Norway to be built using a tunnel boring machine (TBM).

The 1,800 t tunnel boring machine used in Ulrikke was built by the German company Herrenknecht in Schwanau. The boring head of the 155 m long machine is 9.33 m and is equipped with a motor with an output of approximately 5,250 kW.

The first 765m of the 7.8km long tunnel were bored using traditional methods to make a transit loop at the eastern end of Arna station, while the remaining part was bored using of the tunnel boring machine.

Additionally, two diagonal tunnels approximately 150m long were blown out between the old and new tunnels, allowing trains to cross between the tunnels.

Another 16 smaller interconnections are to be blown between the tunnels as escape routes, as well as for use during technical installations.

The first phase of the development of the tunnel and the diagonal tunnels was carried out between November 2014 and October 2015.

Arna station improvements

Arna station will be upgraded to accommodate double tracks leading to Bergen via the new Ulriken tunnel.

Renovation work at Arna station began in January 2017 and is expected to be completed by 2021.

Ramps and stairs will be constructed on the south side of the station as part of the project, along with other track improvements.

A new technical building and technical rail systems will also be constructed as part of the development program.

“The first 765m of the 7.8km long tunnel were drilled using traditional methods to make a transit loop at the east end of Arna station.”

In addition, the underpass under the tracks will be renovated and widened as part of the modernization of the station.

A new temporary platform was opened at the station on March 20, 2017.

Contractors involved

The Norwegian Railway Administration (NSB) awarded a 1.3 billion Norwegian krone (about $194 million) contract for the construction of the Ulriken Tunnel to the joint venture (JV) of Skanska and Strabag in May 2014.

Skanska Norge won a Nkr 275 million ($34 million) contract in June 2017 to upgrade Arna station.

Norconsult were engaged to provide a comprehensive retail plan and construction plan design for the new Ulriken tunnel.

COWI was contracted to provide the signaling system on the Bergen-Fløen road.

NSB has awarded a 97 million Norwegian kroner (about $12 million) contract to NJD to carry out preparatory work along the Bergen-Fløen line.

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