The Liebherr LR 1700-1.0 serves as the pivotal equipment in the remarkable demolition of the bridge. This Liebherr crawler crane is capable of lifting bridge components weighing up to 280 tonnes and stands as the second-largest crane in Emil Egger's fleet.
After years of meticulous planning, a collaborative effort was finalized by experts from the construction firm Max Wild, the crane rental company Emil Egger, the City of Hanau's building authority, Deutsche Bahn, and other stakeholders. This comprehensive plan was aimed at the demolition of the Eisenstrassenbrücke, originally constructed in 1959 and located at the western end of Hanau's main railway station. In the week leading up to Christmas, demolition work commenced, beginning with the first section of the bridge.
This demolition process is highly intricate, with Max Wild executing it in two phases alongside its crane partner, Emil Egger. The operation necessitated the closure of railway tracks and the dismantling of overhead lines. A temporary bridge was established, diversions were created, and numerous trades, institutions, and specialists prepared for this significant demolition endeavor.
By early December 2024, the assembly of the LR 1700-1.0, weighing 900 tonnes and featuring a 60-metre-long main boom as well as a 36-metre-long derrick boom, commenced. Delivered on 38 trucks, the crane was assembled and calibrated by three skilled professionals from Egger, utilizing a 120-tonne telescopic crane to complete the task within three days. This rapid assembly demonstrates the effectiveness of the well-conceived modular concept, which includes 50 tonnes of central ballast, 150 tonnes of revolving platform ballast, and substantial suspended ballast to ensure stability.
The first phase of dismantling is scheduled for completion by 31 December 2024, encompassing 15 lifts that will collectively remove 4,000 tonnes of material. Given the surrounding environment and the sensitivity of the railway infrastructure, demolition via blasting or hydraulic hammers was not an option. Consequently, Max Wild opted to saw out individual segments, each weighing between 70 and 280 tonnes. With the installation of the LR 1700-1.0, operations intensified, with the team working around the clock. During the sawing process, the designated bridge section was secured to the LR 1700-1.0 using lifting straps and chains, ensuring that the load was only released once the final saw cut was completed.
Stefan Beeler, who has been with Emil Egger AG for three years, transitioned to the crane rental company specifically to operate the LR 1700-1.0. He dedicates approximately 600 hours annually to this crane and appreciates its exceptional sensitivity. He acknowledges that while assembly and disassembly are complex tasks, they can be accomplished within a few days using a 130-tonne auxiliary crane, thanks to the crane's precise fit, straightforward plug-in connections, and clear assembly guidelines.
Numerous unpredictable elements have characterized this project, particularly as the 38 trucks transporting the components of the Liebherr LR 1700-1.0 had to maneuver backward beneath the bridge structure to reach the assembly site. The crane has been stationed there since mid-December and is expected to remain until the end of February, as the second assembly phase involving an additional 16 lifts will commence in the latter half of February. The LR 1700, equipped with a 60-metre main boom and a 36-metre derrick boom featuring a 2 x 8-fold reeved rope (winches 1 and 2), is ideally suited for this delicate bridge demolition task.
In the initial dismantled section, the heaviest component weighed 280 tonnes, necessitating the addition of 375 tonnes of suspended ballast. This presented a challenge, as the boom needed to be luffed immediately after the component was released and suspended from the hook. The crane then had to retract a few meters before slewing approximately 180 degrees to gently position the bridge component at the demolition site. While many operators can perform this task, the Swiss are particularly skilled, leading Simon Walcher, site manager at Max Wild, to confidently assert that he has selected the right partner in Egger for this complex construction project.
The LR 1700-1.0 from Liebherr ranks as the second-largest crane in Switzerland and the second-largest in the Egger fleet, following the LR 11000. "Wind power is limited in Switzerland," states Stefan Beeler, crane operator at Egger. Consequently, construction and assembly tasks, particularly involving bridges, buildings, and industrial structures, as well as loading operations in harbors, constitute the core business for the LR 1700. After three years of operation and 1,800 hours of use, the crane appears as though it has just emerged from the expansive Liebherr facility in Ehingen, which spans one million square meters.
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