I have designed the next bridge which will be a 1.25m under arched girder bridge. It proved to be a little more difficult than I had anticipated as I didn't know how to calculate the radius of the arch, but a Google search led me to http://www.mathopenref.com/ which provided the following information.
Given an arc or segment with known width and height:
W is the length of the chord defining the base of the arc
H is the height measured at the midpoint of the arc's base.
I've started cutting the aluminium which was left over from the last bridge, but work has now stopped until I can get more supplies.
|The plan for the next bridge|