TWO SENNEBOGEN 683 R-HDS TACKLE THE SINNTAL BRIDGE

Two SENNEBOGEN 683 R-HDs tackle the Sinntal bridge

In the Franconian town of Bad Brückenau, the A7 Autobahn spans the Sinntal for well over 750 m. The solid-web girder bridge, erected in 1967 was replaced with new construction in 2013. Plannerer GmbH & Co Kg, located in Pullenreuth, was commissioned to demolish the old Sinntal bridge. Two SENNEBOGEN 683 telescopic crawler cranes help to remove parts of the welded truss and plate construction that weigh many tons.

With a length of 770 m and a maximum height of around 50 m the Sinntal bridge is one of the largest Autobahn bridges in Germany. After the new construction was completed in 2013, the steel substructure with a mass of well over 6500 t must now be hauled off piece-by-piece, before the entire construction can finally be dynamited. This is where the advantages of the two SENNEBOGEN telescopic crawler cranes are really brought to bear for the demolition firm, Plannerer.

First, with the aid of flame torches, workers separate the upper structure into pieces as large as 16 t. The 80 t telescopic crane holds these pieces until they are completely cut free, so that they can then be safely conveyed into the valley. In this process good stability and a high winch force are the primary requirements. Even with a rope length of approx. 50 m the machine manages the lift effortlessly. However, the machine experiences the greatest stress when the heavy steel parts are only fastened at a few points. If these fastening points suddenly give way and the crane boom absorbs this force abruptly, this situation not only requires a high level of skill on the part of the operator, it also requires the highest quality components and a robust construction to withstand this peak load.

For the operator, control of the machine via the external remote radio control is an essential work facilitator in this situation. With the remote radio control the operator can monitor the lowering process from the edge of the bridge, and he never loses sight of the load that weighing many tons.

Thanks to the powerful crawler travel gear the SENNEBOGEN 683 can also be used and moved flexibly under load and without outrigger. Stephan Plannerer also uses the telescopic crane for other tasks required for the Sinntal bridge project. For example, to later drill detonation bores in the concrete pylons. Hundreds of holes are driven into the steel reinforced concrete from the attached work platform. But even after the bridge is dynamited, work does not stop for the two SENNEBOGEN telescopic crawler cranes. Finally, lifting in tandem, they will transport off the demolition pieces that are 30 m in length and many tons in weight.