Aarsleff Ground Engineering AB execute Swedish railway upgrade scheme

[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, 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 eight meters above ground.

Aarsleff’s ground engineering team commenced work 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 1,500 reinforced precast concrete piles with additional foundations 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 and 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 sections, Aarsleff is using a system where an open-ended steel pile is driven to 4-6m, followed by a micropile installed through its base. The former will provide resistance to compression and lateral loads and the latter to tensile capacity, thus increasing the system's stability in strong winds.

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 nine piles a day on a weekend and up to five piles in a weekday. The aim is to execute 35 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 eight separate units. For the main works, Aarsleff utilise the compressor component for the drill, and a crane to lift and handle the piles. Since 21 May Aarsleff have been 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 six 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 startup 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.” q • For further information visit the website at www.aarsleff.se or email grundlaggning@aarsleff.com