When it was discovered that the home of nesting ospreys was directly in the path of the proposed Tewantin Bypass road, the Sunshine Coast Regional Council made a commitment to give the ospreys a new home.
A plan was made to relocate the upper part of the tree containing the nest; and splice it to the top of a new timber pole. The Sunshine Coast Regional Council engaged Tod Consulting to carry out the Structural engineering design.
Chris Dowding of Tod Consulting enjoyed this unusual challenge. Wind loads were calculated with stresses and sways checked for three different pole options.
“It was important that we gave the birds an environment that felt similar to their old home,” said Chris. “The diameter of their original tree was 1050mm at the base. An early proposal was to use a timber pole that was 450mm diameter, but the horizontal sway under wind loads would have been enormous. Fortunately the Council and Energex were able to get a 750mm diameter pole, which was a lot closer to the original tree diameter.”
Tod Consulting also provided the design for the concrete footing and most importantly, the connection to splice the tree to the pole.
“There was an initial idea to use a modified form of the connection that Energex uses to fix transformers to the side of timber pole,” said Chris. “With the tree top, this was unsuitable, because it cantilevers much further from the fixing point than a transformer. We modified the initial idea to be a 2m long steel pipe section that slid over the top 1m of the pole and was glued with high-strength epoxy supplied by Epirez. The tree top was then lowered into the protruding part of the steel pipe and any gaps were filled with the same epoxy.’
The day after the construction work was completed, Council workers observed that the ospreys had moved back into their nest. Recently, it's been reported that the ospreys have laid an egg. Tod Consulting is proud to be part of the team that relocated their tree top home.
For more information:-
Council’s project webpage. Click (here)
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