Sunday, January 17, 2010

farmdoc's blog post number 637

By lunchtime last Thursday all 340 decking spikes were in place. Each of the 66 decking plank has 4-6 spikes in it, i.e. a minimum of one into each of the four underlying bearer logs, with the wider planks getting an extra 1-2 spikes for good measure. Each spike’s eight inches (i.e. 203mm) long, with a 9mm diameter. So the new bridge is strong. Really strong. Roughly estimated, its load tolerance is 40-50 tonne. Better to be over than under engineered, eh. In early February the plank ends will be evened up and the side barriers put on. Then the new bridge will be complete.

As the photo below shows, the Blairs have also positioned giant log sections on the bridge approach – to which they’ll attach post-and-rail fencing. That’s it for this series of bridge replacement posts, folks. But I’ll do a final bridge post in early February after the job’s finished. Normal Farmdoc’s Blog postings will resume tomorrow.

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