Six cranes install 71m skywalk

25 August 2020

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Hanover-based Nolte Autokrane installed a 70m cantilever connection bridge made up of four components and a number of connecting elements which had to be assembled in the air between two buildings of the newly erected headquarters of Continental AG (Conti).

The Nolte team arrived at the site of the new Conti headquarters to tackle a complex, marathon job. Six Liebherr mobile cranes were required to tackle the job on one of the city’s busiest arterial roads: an LTM 1250-6.1, three LTM 1200-5.1 and two smaller mobile cranes.

Each of the trussed girders measuring 36m and weighing 38t were hoisted into position by one of the four large cranes. A number of trees, traffic signs and the overhead cables for the tram line meant that it was impossible to hoist the complete construction from the ground. This meant that each two opposite bridge sections to be connected in the air and then positioned on the abutments on the new buildings at a height of eight metres.

“The components were not bolted end to end but were slid conically into each other and then connected with enormous adjusting bolts”, explained Jürgen Peters, Nolte’s project manager. Peters planned the job down to the last detail and completed the assembly of the walkway over the wide Hans-Böckler-Allee using a 16-man team working in two shifts.

The four Liebherr cranes held the bridge sections for 22 hours whilst the two small machines took care of the installation of around 70 steel top and bottom chords for the side lattice components. The loads were then attached and the small cranes started installing the safety equipment under the new bridge structure.

Peters was extremely satisfied once the job had been completed: “We arrived with our cranes on Friday evening, 22 hours later the bridge had been installed and the safety equipment under the skywalk was installed on Sunday evening. The whole job went like clockwork.”

At sunrise, the elements of the second side of the bridge were connected to the crane hooks.
Each of the components weighing 38t had to be slid conically into each other.
The four large Liebherr mobile cranes were still holding the various lattice structures for the future connecting bridge between the buildings. Two other cranes were installing the cross-connections at the same time.
The four lattice structures had to be unloaded and positioned vertically in very restricted conditions.