Bridge construction

The C.M.G.R. crosses a manhole cover on its way round the garden. As this is not in the main viewing area, I decided to build a simple, inexpensive girder type bridge to span this. The sides are formed from two 1m lengths of 1.5mm thick aluminium angle with 20mm wide sides. This picture shows the bridge upside down. The cross struts are 2mm thick by 15mm wide aluminium strip fastened to the sides with 3mm screws.
The aluminium angle sides are supported at either end directly by the concrete track bed, and simply slide in place over this. The gap is around 760mm, so there is a supporting overlap of 120mm either end. The 10 cross struts are 76mm apart, this being exactly twice the sleeper spacing of the Peco SM32 track. In other words, every other sleeper is supported by a strut.
The finished bridge is secured in place with a screw at each corner into the concrete. Two of the sleepers on the bridge are also screwed to cross struts.
The total cost of the bridge was under 10 including the track. It took just a couple of hours to build, and at least from a normal viewing distance, looks like a reasonably convincing girder bridge.