Milestone achievement for Cityringen 3 Feb 2015

Double breakthrough into Copenhagen Central Station marks a major milestone in the construction of the Danish capital’s US$3.8 billion Cityringen project.

The second pair of Kawasaki-Seli 5.78m EPBMs (Eva and Minerva) – launched separately in July and August last year (2014) for the Italian Salini-Impregilo/Maire Tecnimont/Seli JV – broke through the headwall at Copenhagen Central last Thursday (29 January) to complete 1,360m drives from the control and maintenance loop south of the main ring at Vasbygade, via the Sønder Boulevard launch and reception shaft.

Breakthrough joy for Salini-Impregilo/Seli at Copenhagen Central Station

Arrival at Central Station marks the end of TBM Eva and TBM Minerva’s first drives. Both machines will now be disassembled and transported to the launch shaft at Nørrebroparken in the north west of the city for their final clockwise 4.7km long parallel drives through to the shaft at Oster Søgade, via five stations in between.

In the original plan of attack TBM Eva and TBM Minerva were to have been transported the short distance from Copenhagen Central to the launch and reception shaft at Sønder Boulevard, just 500m to the south east. From here they had been due to complete the short clockwise 1,439m drives through to Frederiksberg Allé, via the station box at Enghave Plads.

However, in September last year the TBM schedule was changed and it was decided that the first pair of TBMs (TBM Nora and TBM Tria) would instead be driven on through Frederiksberg Allé – from where they were due to have been extracted – and all the way through to the shaft at Sønder Boulevard.

Fig 1. Revised TBM plan of attack

Fig 2. Cityringen TBM progress (29 January 2015)

The first of those machines – TBM Nora – finally holed through into Frederiksberg Allé Station, on the western side of the Cityringen alignment, on January 15 (2015). This followed nearly six months of arduous tunnelling along a tough 949m section between Frederiksberg and Frederiksberg Allé. Nora has now completed 3,398m since launch 17 months ago (August 2013) from the shaft at Nørrebroparken. Her sister machine, TBM Tria, is approximately 500m behind, and according to Metroselskabet is scheduled for breakthrough at Frederiksberg Allé in mid-March (2015).

All four machines procured for the project were manufactured at the Seli factory in Aprilla, Italy, under a license agreement that features a Kawasaki drive unit and screw conveyor fitted with a Seli cutterhead. They are designed for a complex Copenhagen geology that sits under a high watertable, ranging from sound Copenhagen limestone with bands of flint, to till and glacial deposits of sand, gravel, silt and clay. The cutterheads are dressed with both discs and scrapers and the machines are tested to 9 bar working pressures to operate under the anticipated 4.5 bar pressures of the alignment as it runs between 7m and 42m deep. The 5.78m diameter machines have a maximum cutterhead thrust of 42,000kN, a cutterhead speed of 0-5 rev/min, a cutterhead drive power of 1,200kW and are fitted with a vacuum segment erector.

As of this week the Cityringen owner organisation, Metroselskabet, reported to TunnelTalk TBM progress of almost 9km of the total 32km of running tunnels. The €1.7 billion contract held by Salini-Impregilo and its partners also includes construction of 17 new underground stations, as well as a crossover cavern under the lake at Sortedams Sø to facilitate construction of a northern extension as part of a separate contract (Fig 2).

This 3km extension to North Harbour (Nordhavn) – which includes 1.8km of twin running tunnels and a 350m cut-and-cover ramp section – was awarded to the Hochtief/Züblin JV for a contract price of 310 million in May last year. A funding agreement is also in place for the €1.15 billion South Harbour (Sydhavn) extension, which will be run mostly underground.