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.
