Tight location, tight schedule: Thömen performs bridge dismantling work in Hamburg

Every day, an impressive 900 regional and long-distance trains cross the two ageing railway bridges “Ferdinandstor” and “An der Alster”. Deutsche Bahn has set itself the goal of minimising the impact of the reconstruction work on its ongoing railway operations. The planning and coordination work before and during the construction phase is intensive; the time window for crane deployment is precisely defined and the work on site needs to be highly focussed. Crane and heavy haulage contractor Thömen, part of the Hüffermann Group, is in charge of the operation with four Liebherr mobile cranes on site: an LTM 1650-8.1 with its LTM 1160-5.2 auxiliary crane and an LTM 1350-6.1 with a 130-tonne crane serving as an auxiliary crane. The LTM 1350-6.1 belongs to the company Eisele, which is also part of the Hüffermann Group. “Our job here is to excavate the existing bridges. Due to the tight time window, we also work at night. The cranes are in operation 24 hours a day, seven days a week,” explains Steffen Wilken, a sales representative at Thömen.

Cramped working conditions require precise planning

One of the biggest challenges the team faced was the lack of space for the four heavyweights near the main railway station in the busy heart of Hamburg – there wasn't enough turning radius available for the 650-tonne crane. Creative solutions were required, as Steffen Wilken reports: “Due to the tight space conditions, we had to jack up the LTM 1650-8.1 very high. We supported it with excavator mats and base plates, so the ballast of the crane could swing over an existing bridge foundation 3.5 metres high.” His colleague Marc Kuebart, who was responsible for the CAD planning and project management for the job, adds: “An auxiliary cable bridge, which had to be erected in advance, was the biggest challenge in terms of deploying the crane. It also significantly restricted the crane's possible working area.” Therefore, maximum concentration and careful work were at the top of the agenda. The LTM 1130-5.1 had already been tasked with lifting the crane parts over the auxiliary cable bridge during assembly of the LTM 1350-6.1. However, this proved to be no problem for the crane drivers, who completed all the lifting work carefully and professionally.

The existing railway bridges were then excavated in 60-tonne sections and unloaded onto a designated, prepared site. On steel plates protecting the ground, the workers cut the bridge sections into manageable pieces for removal.

Currently, in the second construction phase, six divided auxiliary track bridges are now being installed, each weighing 50 tonnes. “The first challenge is to convert the 650-tonne crane with the luffing lattice jib under these extremely cramped conditions. The 350-tonner is serving as an auxiliary crane to assemble the 21-metre-long lattice jib,” explains Marc Kuebart, who knows the details of the work processes inside out. According to Deutsche Bahn's plans for the project, the new auxiliary bridges will be situated above the existing abutments, which need to be dismantled. This will allow for the demolition of these abutments below the rolling railway traffic, and for the construction of substructures for the new railway bridges.