Slender pillars for motorway bridge on the new A 44

Rädlinger Ingenieurbau uses circular column form-work from PASCHAL

The motorway bridge near Herleshausen on the border between Hesse and Thuringia is to have slender, round pillars. This is why Rädlinger In-genieurbau GmbH, the company responsible from Cham, decided in favour of the steel circu-lar column formwork from PASCHAL.

It is probably one of the longest planning and con-struction periods for a motorway in the history of the Federal Republic of Germany. It was approved by the Federal cabinet in 1991, but the A44 motorway between Kassel and Eisenach has been under con-struction since 2000. Once completed, the motor-way will serve as an important east-west link be-tween the old and new federal states. Six of the twelve sections of the new construction, with a total length of around 70 kilometres, have been complet-ed and five are under construction.

Deutsche Einheit Fernstraßenplanungs- und -bau GmbH, DEGES for short, is responsible for a sec-tion of the new motorway that is almost 30 kilome-tres long. For the construction of the section of the A 44 from the Waldkappel junction to the Wommener Dreieck interchange and the transition to the A4, it commissioned a consortium consisting of Josef Rädlinger Bauunternehmen and August Reiners Bauunternehmung in the area between the Ried-mühle viaduct and the Wommener Dreieck inter-change (5th construction phase). Rädlinger Inge-nieurbau is responsible for the construction of the bridge at the Wommener Dreieck intersection, which leads from the A44 motorway to the A4 motorway in the direction of Frankfurt. In May 2023, construction work began on the ramp structure and with it the work on the formwork for the four piers of the via-duct.

Formed in two “shots”

PASCHAL circular column formwork with a diame-ter of one metre was used. 

The four piers of different heights – they are be-tween 13.80 metres and 15.50 metres high – were each formed in two cycles. Andreas Üblacker, Head of the Bridge Construction Department at Josef Rädlinger Ingenieurbau GmbH, was the project manager responsible for the construction of the piers. He explains the procedure for the “first shot” with a height of seven metres: “After the working scaffolding has been attached to the formwork, half of the pier formwork is placed. We then attach the pre-woven reinforcement cage to the connecting re-inforcement, which rises about two metres from the foundation. Then we close the formwork.”Two to three days after concreting is finished, the concrete has hardened and the seven metre high pillars are now firmly anchored to the ground. However, the formwork remains on the lower part of the pier while the second cycle is concreted. “Due to the slim cross-section with a diameter of one metre, the low-er part of the formwork provides even more sup-port,” Mr Üblacker states.

The work on the formwork for the motorway bridge connecting the A 44 with the A 4 near Herleshausen – a total of eight concreting operations for the four piers – was completed within six weeks. “Whenever there was a gap, we added a pillar ‘just like that’,” the project manager recalls.

The advantage of steel formwork

The small pier diameter was one reason why the formwork solution from PASCHAL was used. “Steel formwork can absorb significantly higher concrete pressures and we are able to achieve a nice curve. If we had made a template from wooden elements ourselves, we would have ended up with a polygonal circle rather than a beautifully shaped curve,” Mr Üblacker explains. And adds: “PASCHAL is one of the few suppliers to offer steel formwork with a di-ameter of one metre; competitors either only have wooden formwork in their portfolio or offer formwork for diameters up to 80 centimetres or then again from 1.50 metres.”

The client and the design planners opted for a diam-eter of one metre in order to achieve harmonious, slender proportions, even if the concreting would be somewhat more challenging as a result. Larger pier diameters would result in significantly greater con-straints on the structure’s bearing system, and even slimmer ones would be problematic from an aesthet-ic point of view. The Rädlinger project manager al-ready knew the PASCHAL’s portfolio, as this was the second cooperation with the formwork manufac-turer from Steinach. The circular column formwork was already used in 2019 to build the guest entrance for the Allianz Arena in Munich – an elevated plat-form. As a result, Mr Üblacker turned to the form-work consultant and head of the Lower Bavaria branch, Jürgen Fuchs, for the motorway bridge pro-ject in order to obtain a feasibility assessment and a quotation. “I originally became aware of the PAS-CHAL company because I had seen gantries on the motorways that stand on foundations with rounded ends. The manufacturer, who specialises in these signs, is a regular customer of PASCHAL and so they recommended the formwork company. That’s how we came to work together on the Allianz Arena project,” the head of the bridge construction depart-ment at Rädlinger relates.

Attention, power line!

What made the work on the ramp structure of the A44 motorway near Herleshausen a particular chal-lenge was the fact that a high-voltage power line crosses the structure and therefore a safety distance had to be maintained during the concreting work. There was about twelve metres of space between the upper edge of the piers in their final state and the power line. “An altitude limit was set that we were not allowed to exceed. This is because power lines continue to sag depending on heat exposure,” An-dreas Üblacker explains. This meant that the first cycle could be concreted with the help of a concrete bucket attached to the crane. During the second concreting section, the concrete pump was used to ensure that no one entered the safety zone of the overhead line.

As soon as the weather permits this spring, the top of the bridge will be sealed with resin; then the caps will be concreted, which will serve as an emergency walkway for the motorway, among other things, be-fore the asphalt carriageway between the kerbs completes the structure. The bridge is expected to be completed in spring 2024. Construction of the en-tire route section is scheduled to be completed in spring 2025. Due to the tunnel’s operational equip-ment, it will not be possible to open the tunnel to traf-fic until 2026.