After the completion of the new highway bridge on the A43 in France, the dismantling of the old Viaduct of Charmaix was necessary due to its structural issues. The challenge was in the fact that a part of the old bridge crossed a nature reserve, ruling out conventional demolition methods. The specialized demolition company Despe from Italy was entrusted with the complete task. In collaboration with Mammoet Italy, Schmidbauer developed a concept for the bridge lift using the new LR 11350 crawler crane. This crane stands out for its exceptional performance – even at an radius of 67 meters, it can lift an impressive 249 tons, and at an outreach of 93 meters, still an astonishing 150 tons. Another advantage was that the crane could be quickly deployed directly from Marseille, where it had previously been successful in the offshore PGL project.
The project posed a significant challenge from the beginning, starting with the journey to the construction site. Due to the limited capacity for a special entry of only 5 trucks per day directed by the highway, the transport was delayed significantly. Additionally, all vehicles had to turn on the highway, as the access was only in one direction, and these maneuvers were only possible at the entrance to the Fréjus road tunnel. Furthermore, the tight curves and the incline to the crane area required that all trucks be transferred to a special all-wheel-drive truck. About 30 meters of gravel road had to be overcome to reach the site. "In total, there were 80 heavy transports that arrived here. And no space for parking, turning, or storing. It was madness!" reported our Technical Field Service representative Oliver Thum.
The crane assembly was similarly complex: the crane space on the mountainside was extremely limited. The jib had to be mounted along the steep access road, uphill and partially floating, requiring precise planning and execution. Moreover, there were only two locations for the auxiliary crane needed for the assembly of the 108-meter-long boom. According to Oliver Thum, the challenging terrain during the assembly of the lattice masts was an extreme ordeal. Due to the difficult circumstances, the crane assembly took three weeks instead of three days.
With the LR 11350 crawler crane, the massive concrete beams were to be lifted from the extremely tall pillars. The 40-meter-long bridge beams were first lifted, then the outreach was shortened, and the additional load of the Superlift was detached. This showcased the impressive lifting capacity of the crane – even without the Superlift. Subsequently, the crane was rotated 180 degrees, allowing the bridge beams to be laid down for destruction at the designated locations. The crane handled all lifts on its own, only receiving assistance from a 700-ton mobile crane for the last and farthest beam during tandem lifting.
All these difficulties turned the project execution into a logistical and technical masterpiece, taking approximately three months. This vividly illustrates how innovative approaches can successfully overcome demanding challenges. By mid-December, the dismantling of the old viaduct was completed. Due to the extreme winter conditions and additional daring circumstances at the site, the crane dismantling only began last week, and the project is now officially concluded.
Equipment:
Location: Modane in the district of Fourneaux, France
Duration: Mid-September 2023 until the end of December
