The subject is a wooden bridge - we have heaps of these in our rural area that cross creeks that are mostly dry creek beds until it rains - and they require a lot of maintenance. This is one in our region that created problems when a school bus's wheel literally dropped through a rotten plank in the middle section and on investigation the under-bridge was found to be seriously effected by dry rot.
It's a busy bridge and any detour is quite lengthy so it had to be fixed quickly as its use is high demand. Unfortunately the creek was a steep and narrow ravine.
Even in retirement my advice is still sometimes sought. I was consulted on how to do the job 'quickly' (normally a bridge crew of two or three men will takes week to repair this degree of damage, approaching the job in a 'piecemeal' fashion.) I was told I had a 'window' of three days over a weekend in which to plan for the job to be completed. Residents were advised beforehand and for the school buses it was a 'pupil-free day' for the local schools with high school students being granted a 'study day'. (LOL - a 'study day' for rural teenagers - like 'Yeahhhh'!)
Bearer eroded with dry rot exposed.
My advice was to install scaffolding under the bridge to give the bridge carpenters a safe platform to work from, remove the bolt ties and then lift out the good road section complete using a mobile crane, expose the damaged area, repair it and then swing the undamaged section back into pace and lay a new deck to replace the damaged middle section.
Day 1, Friday- safety scaffolding is erected under the bridge and the damaged decking section removed.
The damaged bearers exposed after the decking was removed.
The section to be lifted out is that which the man in the yellow
top is standing on - the bearers ran under him to the 'header' piece
on the approach buttress.
Day 2, Saturday - the undamaged end deck is lifted out of the way to allow all dry rot timbers to be removed, new 'bobbles to be put in place (those funny little short pieces on top of the trestle the man in the orange shirt is standing on) and new bearers to be laid.
Day 3, Sunday - the good piece of decking is swung back into pace over the new bearers and new middle decking planking installed, scaffolding removed from underneath.
Monday morning - job completed and the bridge is ready for normal traffic.