Replacement of the Thalaubachtal bridge
Hesse, Germany
A sense of timing
Built in 1968, the Thalaubachtal Bridge in the south of the central German city of Fulda can no longer cope with today's traffic. This conclusion follows an inspection by the German Federal Motorway Authority (Autobahn GmbH).
The almost 60-year-old Thalaubachtal bridge is a 7-span steel bridge on the A7 motorway, spanning the B 279 federal road, several country roads and the Thalau stream. It spans the two carriageways in the direction of Kassel (substructure 1) and Würzburg (substructure 2) on two separate superstructures.
The Thalaubachtal bridge is a typical low mountain valley bridge: wide but not too long crossings over valleys, the Thalau stream and roads – and no conventional shoring possible underneath. Under these circumstances, the incremental launching method was the most economical solution for the bridge superstructure and was specified in the tender issued by Autobahn GmbH.
In terms of formwork, work began on the new construction of the eastern half of the bridge towards Kassel, directly next to the existing bridge. The first step was the construction of the six piers, including the pier heads, which will eventually carry 12,000 tonnes of superstructure. The highest pier is approximately 35 metres high. Approimately 25 metres (and 6,500 tonnes) of bridge will be pushed forward onto each pier in each cycle.
Building type
Motorway Bridge
Challenge
Very tight timeline for this viaduct and no conventional shoring possible underneath. Overall concept for 6 piers including pier heads, which will eventually carry 12,000 tonnes of superstructure"
Solution
Economical and environmentally friendly implementation using the incremental launching method with 100 meters of bridge per month. Within a tight timeframe, the Doka's bridge team successfully developed an innovative formwork and service concept for piers, pier head, and superstructure formwork through their in-depth expertise and close collaboration.
Experience of similar bridges included
When it came to the formwork, contractor Kropp Bau GmbH brought Doka on board as an experienced bridge specialist. The Thalaubachtal bridge is currently the third viaduct on the A7 motorway that Doka engineers and formwork instructors have had the honour of planning and supervising using the incremental launching method. The Rothof Bridge and the viaduct near Langenschwarz on Germany's longest motorway (962 km) have already been constructed using this method.
"This creates trust, as Marco Witzel, one of Kropp's two managing directors, points out: "We don't just want a service provider who works on a job, we want a real partner whose expertise we can rely on to deliver a good result in the end". A well-functioning team is essential, especially in projects like this with a tight schedule.
At a very early stage, before the formwork had even started, Doka pointed out many small details that they had learned from previous bridge projects. "For example, they advised us on interface issues, such as coordination with the shoring supplier for the casting yard," says Kropp's Project Manager Sophia Hohmann. Her colleague, Senior Site Manager Gernott Rott, adds: "Even for the formwork planning itself, the colleagues from Doka had valuable tips from previous projects, without which more time would have been needed to find solutions. For example, round-off web sections. Or that we needed a bend in the cantilever formwork for the superstructure, for the installation parts for the later drainage. All this had already been worked out in the Langenschwarz project.”
Paul Schimrosczik | Product Manager | Doka GmbH
"The incremental launching method is one of our favourite methods for building large bridges. The amount of material required is comparatively small in relation to the construction progress. If you keep to the weekly cycle, you can build 100 metres of bridge per month, which is always a fascinating scale," says Paul Schimrosczik, who is in charge of the project on behalf of Doka Germany. Particularly interesting for contractors: The fact that Doka has already built so many bridges of this type means that the team knows the cost of the pier and pier head formwork and the superstructure formwork in the casting yard for various design concepts. "This enables us to provide a realistic cost calculation that also includes ancillary formwork elements, such as stair towers or additional working platforms at the pier heads. This gives the client certainty in their calculations."
Project data
Project duration
2022 - 2024 (1st bridge section)
Client
Federal Motorway Authority
Country
Germany
Contractor
Kropp Bau GmbH
City
Eisenzell-Döllbach, Hesse
Building data
Construction method
Incremental Launching Method
Construction Type / Segmentation
Pier, Pierhead, Superstructure
Total length
312m
Section width
16.55m
Section length
25m
Number of sections
13
Pier height
45m
Cycle time
weekly cycle