Trafikverket, The Swedish Transport Administration, is modernising the railway from Varberg to Borås by replacing tracks, the overhead line and signal-box and introducing remote control on selected stretches of line.
On behalf of main contractor Leonhard Weiss, a team of several Aarsleff companies is responsible for the design and build of the entire catenary system, from the deepest foundations to the wires and cables 8m above ground.
There are differing ground conditions on site – including clay, peat, rocks, stone – and so Aarsleff will be installing a variety of foundations from short 4m-long precast piles of 355mm diameter, to 6m-long piles with a diameter of 555mm.
In some cases, Aarsleff will install duct foundations with a foot whereby excavation is required into the ground. The 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. Only a limited number of these special piles will be installed.
The existing power lines are being turned off every evening to allow Aarsleff’s work along the track. This provides Aarsleff with only a certain amount of time to be in and out of the site, which is particularly challenging when multiple shifts are restricted to a five-hour working window.
The initial aim is to execute 35 foundations every week, which is hoped to increase as operations become more mature.
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 masts and extend the cables out some 1m-1.5m. This operation provides Aarsleff with the space required to carry out the piling operations both safely and efficiently.
To install the foundations, Aarsleff is deploying a train with eight separate units. For the main works, Aarsleff uses the compressor component for the drill, and a crane to lift and handle the piles. From 21st May, Aarsleff will be renting a rail-mounted drilling rig to complete the rest of the foundations on the scheme.
Brian Gravgaard, Per Aarsleff’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”.