Transmission
grid operator, TransnetBW, commissioned LTB Leitungsbau with the construction
of 46 hybrid pylons, which transport both direct and alternating current, as
part of the ULTRANET project. PASCHAL produced special circular formwork for
the construction of the 184 foundation heads. Only the upper part of the round
foundation heads will be visible after completion. They are rounded so that the
farmers' equipment does not get stuck.
ULTRANET is an energy
transition project to drive forward the expansion of the electricity
infrastructure in Germany. New high-voltage direct-current transmission lines
are to transport electricity from northern Germany to the south with low
losses. The transmission grid operator TransnetBW commissioned LTB Leitungsbau
with the construction of 46 hybrid pylons as part of the structural realisation
of ULTRANET. These hybrid pylons can transport both direct and alternating current
lines. The full-service provider for transmission line construction relies on
the PASCHAL LOGO.3 solution for the formwork of the foundations. Special
circular formwork was ordered for the foundation heads that hold the
electricity pylons in place.
In order to drive forward
the energy transition, the share of renewable energies in the electricity
sector is to be increased. The ULTRANET grid expansion project is currently
being realised in order to transport the 'green' electricity produced in the
northern federal states to the southern federal states. ULTRANET is an
approximately 340-kilometre-long direct-current connection of the transmission
grid operators TransnetBW and Amprion in existing routes and extends from
Osterath in North Rhine-Westphalia to Philippsburg in Baden-Württemberg.
TransnetBW is responsible for the approximately 42-kilometre-long section B1
between Mannheim-Wallstadt and the Philippsburg grid connection point. The
project in this section will be implemented as a replacement or parallel new
construction on half of the route, and as an extension to existing lines on the
other half. TransnetBW has commissioned LTB Leitungsbau with the replacement
and parallel new construction of the hybrid pylons in the 21 km section between
Mannheim-Wallstadt and the Neurott substation.
A total of 34 foundation
plates and 184 foundation heads are required for the 46 hybrid pylons on this
route. This means that each pylon is firmly anchored in the four heads. LOGO.3
formwork from PASCHAL was used for the foundation forming; special circular
formwork was produced for the round foundation heads. The formwork work began
in October 2023 and will continue until the beginning of 2025.
Special
circular formwork for the foundation heads: maximum flexibility with three
panel elements of different heights
LTB Leitungsbau had already
had customised circular formwork by PASCHAL produced for previous transmission
line construction projects. René Wolf, civil engineering team leader at LTB
Leitungsbau: 'We have only had good experiences in the past and therefore
decided to rely on formwork from PASCHAL for this transmission line
construction project, too.' The new special circular formwork was commissioned
because the ULTRANET project required a larger diameter of the foundation heads
for the pylons. Previously, diameters of 90 cm to 1.10 metres were sufficient;
for the new hybrid pylons, concrete heads with a diameter of between 130 cm and
210 cm were required. The special formwork with a diameter of 210 cm were ordered
specially and manufactured by PASCHAL for LTB.
LTB Leitungsbau ordered two
sets of circular column formwork with panel elements in three different
heights: 1.50 metres high, 60 cm high and 30 cm high. Two half shells or four
quarter shells are put together to form the round shape. 'With these three
panel elements of different heights – two lower elements and one higher – we
can form all the foundation heads at a height of up to three metres that we
need for this project – and future ones, too. This gives us maximum
flexibility,' confirms team leader René Wolf. The height varies because the
foundations have to be at different depths, depending on how uneven the terrain
is.
After completion, only the
top 40 centimetres of the heads remain visible. The corner posts of the pylons
are set in concrete in a round foundation to increase the collision protection
against farmers' equipment. Mowers and threshers are much less likely to get
stuck on the round concrete heads and therefore do not cause any major damage
in the event of a collision.
Strong
support for the 70-metre-high hybrid electricity pylons
Two formwork sets of 8
panel elements are sufficient to form the foundation heads for two pylons in
parallel. The heads stand on a foundation slab, for which LOGO.3 formwork is
used. 'LOGO.3 is actually our wall formwork, but it can also be used for
creating foundations,' explains formwork consultant Ralph Voigt, who is
responsible for the project at PASCHAL. A total of 144 square metres of LOGO.3
formwork are currently in use. A 1.35 m-high panel element is used to form the
11.80 x 11.80 metre and 70 cm-thick foundation slab. The four corner posts of
the pylon are then anchored in the slab.
Ralph Voigt explains the
procedure on site: 'After the excavation pit has been dug, the steel structure
is assembled and aligned in line and level; then the reinforcement work follows
before the formwork is carried out. The LTB Leitungsbau employees then install
the pylon and pull the transmission lines.' An impassable or sloping terrain
naturally makes foundation construction more difficult. Ralph Voigt explains
further: 'Sometimes it is not even possible to produce a single foundation slab
for a pylon. In this case – on the section between Mannheim-Wallstadt and
Neurott – it was flat enough to produce a single plate onto which all four feet
of the pylon are then anchored. Nevertheless, the logistics of a project like
this are always a particular challenge for the construction workers.'
Challenging
logistics: On the 'digger mats' to the site of the pylons
Although the terrain in
Baden-Württemberg – where the existing and new routes run – is not as
impassable as in other projects, a construction road still has to be laid for
each new pylon – in construction worker jargon, these are referred to as
'digger mats', i.e. when steel plates are laid across the fields for the heavy
vehicles. These routes can be used, for example, to transport a construction
site crane, digger, telescopic handler and other heavy equipment to reach the
individual sites in order to construct the pylons and attach the additional
transmission lines.
The entire route for the
ULTRANET project is due to be completed by the end of 2026 and will then supply
southern Germany with electricity. ULTRANET is then to be extended to Emden on
the North Sea coast by 2027.
PASCHAL
produced special circular column formwork in three different heights to form
each of the four foundation heads for a pylon. This was used to form heads up
to a height of 300 cm and a diameter of 210 cm.
