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Case Histories

NORWAY

DATE: 2014

MODEL: MC 40 (MC 3000)

Entreprenørservice AS has been commissioned with the foundation works of the Paulertjønn bridge, on the Vestfold railway line, in Norway.

The Vestfold Railway Line (Norwegian: Vestfoldbanen) is a 137.79-kilometer (85.62 mi) railway line which runs between the cities of Drammen and Eidanger, South-West of Oslo. Opened as a narrow gauge line in 1881, the line is exclusively used for passenger trains. The route is very little rectified and carries the stamp of the 19th-century building techniques, with many turns and low capacity. Since the 1980s there have been plans to upgrade the Vestfold line to high speed.

The modernization project is part of a wider infrastructure plan (the National Transport Plan NTP 2010-2019) and involves the three sections of the Vestfold Railway Line.

The Barkåker – Tønsberg section has a total construction length of 7.8 km. The new double track railway was completed in November 2011.
The Holm – Nykirke section, in the northern Vestfold, is one of the largest parts of the project. The new 14km double-track section will replace the current 15km single-track service.This new section includes a 12.3km rock tunnel and a new underground station that will be built inside the mountain under the town of Holmestrand. Construction started in August 2010 and is scheduled for completion in 2016.

On the Farriseidet-Porsgrunn section, a new double-track railway will replace the current alignment. The new route of 23km includes seven rock tunnels (between 110m and 4,700m long) for a total of 14.5km, as well as ten bridges, at a total cost of about 740 million Euro. Construction started in 2012 and is due to be completed in 2018. The new tracks are laid to support high speed train service at 250 km/h.

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Works are currently in full swing on the Farriseidet-Porsgrunn section for the construction of the Paulertjønn bridge, by the entrance of the approx. 3.7 km long Martineåsen tunnel. Entreprenørservice AS was commissioned to execute the drilling and sheet piling for the foundations of the 343m-long bridge. The Norwegian company, headquartered in Bærum, south of Oslo, is working as a subcontractor for Skanska.

“We will install about 60 sheet pipes with 813 mm diameter and an average length of 40 meters,” says Ørjan Ausland , rig operator at Entreprenørservice AS. He explains that the project involves about 2400 drilling meters in connection with the bridge foundations. To perform this work, the company has invested in a new drilling rig, an Italian-manufactured Comacchio MC3000. This is the fifth and so far the largest Comacchio rig that the company has acquired through the Norwegian dealer of Comacchio IRM Norway AS.

“This drilling rig is also among the largest in the extensive model range of Comacchio,” explains Alessandro Comacchio, territory sales manager. “The machine is equipped with an engine delivering 188 kW (295 HP) power and features a special mast with a total length of 20.25 meters and 16 meters feed stroke providing 30,000 daN pull up force. This makes it possible to use 12-meter pipes. It can also be folded for reduced shipping dimensions. The design of the machine was adapted to incorporate the requests of Entreprenørservice and allow the use of casings of 813 mm diameter. We also developed a new type of automatic down-the-hole (DTH) lubricator that facilitates the use of the DTH-hammer. The machine features a variable width undercarriage with adjustable hydraulic jacks, providing a wide, stable base for operating on the one side, and a narrow gauge that allows access to confined jobsites on the other.”

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Some modifications were made to allow the installation of reverse-circulation (RC) drilling equipment from U.S. company Holte Manufacturing. For the RC method the compressed air for the (RC) DTH-hammer is blown down between the outer and inner pipes in the double-wall RC drill string, through the hammer and drill bit. Drill cuttings are then blown up through the center of the drill bit, RC hammer and drill pipe, and brought out through a 6” hose pipe for discharge into a container/pond. The equipment supplied to Entreprenørservice by Holte Manufacturing includes a rotary head, "casing driver", DTH hammer, drill bit and drill pipes.
The "casing driver" is a special unit that makes it possible to "hammer" the casing down from the top instead of pulling it down with the drill bit through a welded drill shoe. The 20" and 24" DTH hammers cover casing diameters from 508 mm to 1016 mm (20” to 40”).

The rig is designed to be used with 12 meter drill rods, but when working at Paulertjønn bridge, it is used with 6m-long casings with a diameter of 813 mm. The drilling rig is placed on a solid platform in the swampy terrain. This is the only way to get access to the area where the bridge foundations will be cast. Ausland explains that the ground consists of marsh and mud. He has to drill through two to three meters of marsh before reaching the hard clay layer. “It 's almost like drilling in rubber,” he says.

Thanks to the use of the innovative radio control system developed by Comacchio, all the machine functions such as trimming, set-up and drilling can be easily managed from one console, thus offering the operator a complete view of the job site and enhanced security.

Once completed the new works will reduce journey times from Tønsberg to Oslo to an hour, compared to the current 90 minutes, and will save an hour on journeys between Skien and Oslo. A modern railway will also provide the ability to run more trains, offering improved service to the people of Vestfold and Grenland areas.

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