Complex night shift for six Liebherr cranes

A cantilever connection bridge measuring over 70 metres in length and made up of four components and a number of connecting elements had to be assembled in the air between two buildings of the newly erected headquarters of Continental AG (Conti).

Hanover-based Nolte Autokrane gave an impressive performance recently in its home city with a crane job that took a couple of days.

The team from crane and heavy haulage contractor Nolte arrived at the site of the new Conti headquarters in good numbers, both in terms of manpower and machinery to tackle a massive marathon job. Six Liebherr mobile cranes were quickly set up to tackle the job on one of the city’s busiest arterial roads, where only recently trams and vehicles were making their way through Hanover’s evening rush hour.

An LTM 1250-6.1, three LTM 1200-5.1 and two smaller mobile cranes were ready for action as darkness fell and the first sections of the bridge were delivered. Trees, overhead cables and traffic signs made the job more difficult Each of the trussed girders measuring around 36 metres in length and weighing around 38 tonnes were hoisted into their later 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. Maximum precision and attention were required from all the crane operators and erection engineers.

“The components were not bolted end to end but were slid conically into each other and then connected with enormous adjusting bolts”, is how Jürgen Peters explained the filigree interactions of the cranes with millimetre precision during the hoisting operations. Peters, the man for large projects at Nolte, had first planned the demanding job down to the last detail and completed the assembly of the walkway over the wide Hans-Böckler-Allee extremely smoothly 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”.

In fact, not only did they adhere to the schedule, they actually completed the job slightly early. Around six hours before the road closures were ended, all the work by the Nolte team had been completed and the last Liebherr cranes were on their way back to the company’s yard in the north of the city.