Polydron Play: Bridges Part 6: Suspension Bridges / Ponts Suspendus

So this is where having the actual Polydron Bridges of the World kit really comes in handy. It makes suspension and cable stay bridges a snap. They can also be made with normal Polydron pieces, but it takes quite a bit more work.

The Polydron suspension bridge from the kit looks like this. It's probably the fastest bridge in the whole kit to assemble:

A suspension bridge made from regular Polydron pieces can be as simple or as complicated as you like. It all depends on how authentic you want it to be and how many pieces you have. My rather complicated version looks like this:

I'm a bit of a perfectionist so I wanted to be sure that it had the suspensions to the left and right of the central part of the bridge, just like in a real bridge. I also wanted to keep the suspension lines as close as possible to being over the deck and not out at some funny angle which isn't realistic. If you're not as picky as I am, then you can make very simple suspension bridges using the same technique with the string.

For this bridge you need:

2 regular plinths (see previous post here)

20 equilateral triangles

8 squares

2 double plinths (see below)

36 equilateral triangles

16 squares

2 towers

54 squares

8 right angle triangles

4 iscoceles triangles

Bridge

14 squares either full or Frameworks

2 to 3 yards of string

Here's the flat layout for the double plinth:

I forgot to take a picture of it constructed, but you assemble it just like a normal plinth.

Here's a picture of one of the towers sitting on the double plinth and it's flat layout which I needed to pull apart a little because otherwise there would be overlapping pieces in the picture.:

The assembly is very basic and pretty easy to see from the picture. Just don't forget the green square on the underside of the top cross section which helps to consolidate the structure.

Now you need to cut two long lengths of string and run them through natural gaps left by the Polydrons in the tops of the towers and down to the regular plinths at the ends. Attach the strings loosely to the plinths so that you can adjust the tension as you go, and be sure that the string sags a little in the middle.

Next, cut small pices of string, making very large knots at one end. Fix the strings between the bridge deck pieces, using the knots to prevent them from slipping through. Tie the other end of the string to the hanging cable, using shorter strings for the very middle and ends of the bridge and longer strings as you get closer to the towers.