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Last updateThu, 14 Oct 2021 10am

Aarsleff execute the pile foundations for railway upgrade scheme in Sweden

Trafikverket, The Swedish Transport Administration, is upgrading and modernising the railway from Varberg to Borås by replacing tracks, overhead line and signal-box and introducing remote control on selected stretches of line. This will reduce operational disruptions and create a modern, robust, and reliable railway system from the south east coast of Sweden towards the North.

On behalf of main contractor Leonhard Weiss Gmbh, the Aarsleff collaboration, comprising Aarsleff Ground Engineering, Per Aarsleff A/S’ Construction Segment, Aarsleff Rail A/S and their Swedish sister company Anker AB are responsible for the design and build of the entire catenary system, from the deepest foundation to the wires and cables 8 meters above ground.

Aarsleff’s ground engineering team commenced on site in mid-April 2021 and will follow a piling program scheduled to complete before the festive season. During this period, Aarsleff will install approximately 1500No. reinforced precast concrete piles with additional foundations installed to strengthen the cable system.

At time of writing, Aarsleff has so far received 30% of the designed foundations, and are currently executing one of the foundation types, reinforced precast piles, with others to follow in August. Once the precast piles are installed, a concrete mixture is poured through and around the pile to ensure it stays erect out of the ground.

Due to the differing ground conditions on site (clay, gytie, peat, rocks, stone), Aarsleff will be installing a variety of foundations from short 4m long precast piles of a 355mm diameter, to 6m long piles with a 555mm diameter. In some cases, Aarsleff will install duct foundations with a foot whereby excavation is required into the ground. A pile foot consists of a 10-12m long iron profile inserted through the pile and into the ground to increase its stability in strong winds. These are special piles and will be installed in a limited number.

During Aarsleff’s work from the track, the existing power lines are turned off every evening. This provides Aarsleff with only a certain amount of time to be in and out - particularly challenging when multiple shifts are restricted to a 5-hour working window.

Aarsleff are running on full production currently, installing up to 9No. piles in a day on a weekend, and up to 5No. piles in the weekday. The aim is to execute 35No. foundations every week, which is hoped to increase as operations become more mature. The distance from the outer rail edge to the foundation must also live up to the safety regulations when placed before installation.

The site is restricted by overhead lines running directly over where the foundations need to be installed. The decision was made to mount hooks onto the existing mast and extend the cables out some 1-1.5 metres. This operation is running smoothly, providing Aarsleff with the space required to carry out the piling operations both safely and efficiently.

To install the foundations, Aarsleff deployed a train with 8 separate units. For the main works, Aarsleff utilise the compressor component for the drill, and a crane to lift and  handle the piles. Indeed, from the 21st of May Aarsleff will be renting a train with a drilling rig mounted on to complete the rest of the foundations on the scheme. In general, regulations in Sweden state that a railroad machine’s engine must conform to Eurocode 5 whereby the engine has to be 6 years old or less to ensure the pollution is as minimal as possible.

Aarsleff adopt smart use of technology when working on railway schemes, integrating an advanced cloud-platform system to organise their people, project data and location intelligence to ensure greater connectivity, project management, and transparency for the entire project team.

Brian Gravgaard, Per Aarsleff A/S’ Project Manager overseeing the projects start-up phase said: “This project marks a true one company collaboration between so many countries and departments. When a large-scale project requires multiple specialist solutions, our companies, and divisions within the Aarsleff group collaborate to draw experience from each other and create value for the customer. I take pride knowing that our companies will have helped play a fundamental part in ensuring a progressive, resilient and future-fit railway system in Sweden”. 

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