The Øresund road and rail link between Sweden and Denmark does not fully open until the middle of next year, but main construction is now complete. And for Swedish lifting company Ralling, it has been its largest project to date. Ralling calls its involvement, which ended in June, as a “million tonne lift”.
Project engineer Bengt Nilsson described it as “everything from providing a 40t mobile crane for mounting the railings on the bridge girders to constructing sea fastenings for the transport of the approach bridge girders from Cadiz in south west Spain to Sweden.” Bridge construction was divided into five elements: high bridge girders, pylons, approach bridge girders, pier shafts and caissons. Apart from the pylons, all these components were prefabricated on land and then shipped to site. The 49 steel approach bridge sections, many weighing around 7,000t when finished, came from Cadiz and the eight steel high bridge sections from Karlskrona in Sweden. Pier shafts and caissons were fabricated at the Malmö factory of principal contractor Sundlink, where final work was also carried out on the bridge sections. A completed approach bridge section, including railway and other equipment, was calculated to be the heaviest lift of the project at 7,464t. This figure was determined from pressure on Ralling’s lifting jacks.
When the bridge sections arrived in Malmö harbour, at a rate of two every three weeks, Ralling dismantled the sea fastenings and moved the sections, which were between 120m and 140m long, into the Sundlink factory by skidding. At first the operation took 25 people seven days for each section, but by the end of the project two years later, this had been reduced to less than three days and 20 people.
Ralling also moved several dozen pier shafts which were up to 51m high. It also lifted and moved 51 caissons, each up to 20m high and weighing as much as 4,800t. A system of 16 jacks, each with 400t capacity was used for lifting both caissons and piershafts. Two 150t jacking units were used to push the caissons and four 100t units did the pushing on the pier shafts.
All bridge sections, caissons and pier shafts were lifted and placed by the heavy lift vessel Svanen, leased to Sundlink by owner Ballast Nedam International. Built in 1990 the vessel has a lifting capacity of 8,200t including rigging and 8,700t without rigging. Maximum hoisting height above the deck is 76m.