Numerous large road and railway bridges in Germany require extensive refurbishment or replacement. An example from Lauffen am Neckar in Baden-Württemberg illustrates that even the replacement of smaller bridge structures at the end of their service life can require sophisticated technology and complex solutions. There, a 75-year-old single-lane bridge had to be replaced, as its load-bearing capacity no longer met the structural requirements. The location of the river crossing, which led from the densely built-up old town across a canal to a small island, presented the planners with particular challenges. Above all, the available space for the mobile crane required a well-thought-out solution of high precision.
“As if made for the compact LTM 1650-8.1”
“The topography on site severely restricted our options for setting up the mobile crane. Thanks to its compact design, the LTM 1650-8.1, with its high lifting capacities, was the perfect machine for this job,” explains Christian Spreuer, a qualified engineer responsible for project planning for large cranes at MSG Krandienst. “Due to the narrow installation area, we had to position the river-side outriggers outside the actual installation plane, using large steel cylinders on concrete foundations situated around four metres lower down. The auxiliary cylinder under the rear of the vehicle was a great help to us during crane assembly, as it made it much easier to support the rear outriggers on the sloping road.”
“All the required load capacities and reach distances could be optimally met with our LTM 1650-8.1,” Spreuer continues. For this purpose, the crane was fitted with a 35-metre luffing jib and loaded with 175 tonnes of counterweight. First, a temporary footbridge had to be erected across the 40-metre-wide canal before work could begin on dismantling the old arch bridge. The construction machines required on the island were also transported to the other bank of, suspended from the hook of the large mobile crane. With a reach of 50 metres, the Liebherr crane set it down safely on the opposite side.
Efficiency thanks to VarioBallast®
After the bridge superstructure, including the deck, had been dismantled section by section, the massive supporting arch was cut into five segments using concrete saws. During the work, which lasted several days, a pontoon positioned beneath the arch, equipped with scaffolding piers, supported the structure. Its height above the canal could be adjusted via a pump system, which was used to flood or drain the pontoon chambers as required. The LTM 1650-8.1 lifted the separated bridge sections one by one. The apex section of the arch, weighing just under 44 tonnes, was the heaviest single load the crane had to handle at a reach of more than 36 metres. Thanks to the continuously adjustable VarioBallast(®), the Liebherr crane carried out all lifting operations with the various load conditions at reaches of 26 to 50 metres swiftly and efficiently.
The 700-tonne Liebherr crane deployed in Lauffen am Neckar is, alongside two LTM 1750-9.1s and another LTM 1650-8.1, one of the most powerful mobile cranes in the 55-vehicle fleet of MSG Krandienst GmbH. The company, based in Kehl on the Upper Rhine, operates in the fields of crane hire and project logistics and, together with its French subsidiary ‘MSG Levage sarl’, employs a total of 175 employees.
