I was thinking perhaps with this extended heat wave, and the proven success of the bridge we built last fall, perhaps I should consider doing the other bridge now. I was demonstrating to Justin that the old bridge, made of beetle-killed pine logs from about ten years ago, was getting a little saggy. I gave a little jump to demonstrate. With a loud crunch it collapsed. Yup, it’s time.
When I was visiting my brother in Jamaica, he gave me the lowdown on the arches surrounding his porch. He’s a big fan of Gaudi’s wonderful architecture in Barcelona, and one of Gaudi’s favorite architectural devices was the catenary arch. The word catenary comes from the Latin word for chain. It is the curve defined by a chain sagging between two points. They are incredibly strong. All Tom’s arches are catenary.
Gaudi could model entire buildings upside down with chains.
Turned right-side up it looks something like this.
Here is one in St. Louis.
So I had to get out a chain and define my new bridge.
A little spray paint captures the shape.
Cut out two of them at once, and cover them with two-by-fours.
Cover it with plastic so the concrete won’t stick to it.
Then build the end-walls out of lava rocks left over from excavating my shop foundations a few years back.
I’m pretty jazzed with how nicely it is coming together.
In goes the conduit for trail lighting and outdoor electric sockets.
A little more rock work and bracing and we’ll be ready to pour cement.