Repair and replace

The two 70t Modulift spreader beams were integral to the reinstallation of a refurbished bridge across the Aare river in Bern, Switzerland's capital.

Senn offers is a specialist steel construction and infrastructure projects, as well as lifting. Its scope of work for installation of the bridge in Aarwangen in the north of the city included manufacture and transportation of the steel structure.

Jörg Senn, CEO, explained that the expansive job specification actually simplified selection of the lifting and rigging equipment from the business's crane and transport department, eliminating the requirement for specifications to be sent to another party, as would typically be the case.

Two big problems remained, however. First, Senn AG had only six weeks to remove the bridge, renew the foundations and replace it; and, second, once the bridge was returned to the site it had to create a stable lift using both the cranes' outriggers and below-the-hook equipment.

It took four nights to remove the old bridge and four nights to put the new bridge in place. Three Senn AG professionals communicated via radio throughout the project but, Jörg Senn, who expects to complete 20 similar tandem lifts this year, said a comprehensive lift plan was key to safe completion of the job.

Senn chose Liebherr models LTM 1130-5.1 and LTM 1160- 5.2, both with capacity in reserve and each equipped with the manufacturer's VarioBase system, a variable supporting base introduced to the market at the Bauma trade show in 2013. Liebherr developed the system with which every individual crane support can be extended to any length and the crane operation is then made safe by a load moment limiter. The extension length and support force of every support is measured and the maximum lifting capacities for a situation calculated.

Jörg Senn said: "The VarioBase system added safety to the lift as incorrect operation can be avoided both during the setup process and when handling loads. Combined with the below-the-hook equipment from Modulift, we successfully completed reinstallation of the bridge during overnight shifts to the strict time schedule."

Senn used two 70t Modulift spreaders. Jörg Senn explained that, again, sourcing equipment and expertise from within the company enabled swift selection of the right rigging gear with precisely positioned lashing points.

He concluded: "We are battling in a tough economic climate here in Switzerland so the Aarwangen bridge lift was rewarding."