Hi,
We have now started serious work on the viaduct at the bottom of the garden, where the railway is at its highest above ground level. It will be a McAlpine concrete poured viaduct.
The unbalasted section shown in the pictures shows where the viaduct is to go. It was scheduled for last spring, but that went by the board.
We spent a lot of time deliberating the construction - as in could we build it round the existing baseboard and supports, but we felt it would be quicker and look better if we did it from the ground up. There will be 9 arches, and the viaduct will be about 16ft long, subject to final survey.
Brian organised 2 steel formers so we could cut whatever material we were using accurately.
I was given some insulated metal panels which would give rigidity to the outer formers:
and we used offcuts of foam insulation sheets to make the overall width up to 32cm. All held together with 'No More Nails' or similar. The 10mm threaded rods ensures alignment and that it stays together while the glue is setting.
From here we shall make sure the outer formers are all at the right height etc, then use expanding foam to fill the gap in the middle. This will be trimmed across the formers when dry, and we shall glue some damp proof membrane round the arch in the hope that we will be able to release it from the concrete......that's the plan. We have made 5 sets of formers so aim to do 2 pours, 5 arches and 4 arches respectively
Richard