Protecting infrastructure
Before those massive towers and turbines can even make
it to a wind farm in waiting, they must be transported in
staggeringly large loads with special multi-axle vehicles to
distribute the weight. And it’s not only the turbine and
tower pieces: A single crane – hauled to the site
disassembled – can weigh a million pounds.
Tom Janke, highway commissioner in Fond du Lac
County, Wisconsin, knows firsthand about these loads.
In 2007, before the Blue Sky Green Field Wind Energy
Center and its 88 wind towers were constructed in
northeastern Fond du Lac County, Janke was informed
that the heavy loads included a maximum single load of
237,000 pounds (think 70 minivans).
Before the components for what was to become the
state’s largest wind farm would be transported over the
county’s bridges and culverts, serious calculations needed
to be done. According to Janke, “Our concern in the
construction of a project of that magnitude was to protect
the public investment in infrastructure. We Energies and I
felt the best way to protect our infrastructure, primarily
the bridges, was to have a structural engineer evaluate the
existing structures.”
We Energies, the owner of the wind farm, contracted
with Ayres Associates to provide bridge inspection
(pre- and post-construction) and load rating services on
five structures to be used en route to the wind farm.
Ayres Associates engineers found that certain structures
could not withstand the load and thus were avoided. In
some cases, recommendations were made to increase
the fill over culverts.
Janke, who has now seen three major wind farms
built in the county, said “you cannot just assume existing
structures can carry the extreme weight of these wind
farm components. It takes the right expertise to evaluate
structures so that the necessary steps can be taken to
ensure the safety and longevity of our structures.”
Additionally, bridge and culvert inspections can be
required for certain construction permits. Janke said
inspections are “a cost-saving measure as well as
insurance both for the contractor and the municipality.
If we would have opted to not take these necessary
steps, in a worst case situation there could have been a
structure failure.”
“Many of the engineering services we have been
providing other clients for years apply directly to the
wind industry,” said Fred Halfen, CP, vice president of
energy corridors services at Ayres Associates. “And
we’re excited to be a part of the alternative energy
movement.”
TRENDS
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