Bridges Part 7: Arch Bridges / Ponts en Arc

This is a bridge that you will not find in the Polydron Bridges of the World kit. They don't address arched bridges at all. However, at I was wandering around on the internet, I came across and arch bridge made from another type of construction toy. I noticed that it used primarily iscoceles triangles and squares for the main structure of the bridge and I knew that I could probably do something similar with our Polydrons.

Here is where I probably have to admit that I have an obscene amount of Polydrons. Those iscoceles triangles are not as easy to come by as the equilateral and right angle triangles are. Generally you find only a few in some of the kits, but I thought I'd show it to you anyway.  No, the arch is not as nicely rounded as I might like, but it still illustrates the concept. I tried to do another one using easier to find pieces, which I will show you farther down.

For this bridge you need:

28 iscoceles triangles
4 right angle triangles
20 squares or 9 solid squares and 11 Frameworks squares
2 rectangles

Here's the flat layout. I had to pull it apart a little because otherwise some of the pieces overlap.

Here's a bridge made from equilateral triangles and squares. It doesn't work out quite as smoothly because there's a jump from the deck of the bridge to the "road" at the ends of the bridge. The middle of the bridge is also a bit pointy, but if that's all you have, you can still make an arched bridge.

For this bridge you need:

24 equilateral triangles
6 right angle triangles
16 squares or 8 solid squares and 8 Frameworks squares
1 rectangle


Here's the flat layout:

I'm not an engineer, but from what I can tell, this type of bridge is used more as a foot bridge because the deck of the bridge actually arches as well. The ones that are used for cars and trains are a bit more complicated in order to keep the deck of the bridge flat. However, it does remind me of ones you can find in Venise.