The link to his page is http://koi-z-are-us.20m.com/bridge_of_the_four_seasons.htm

Small bridges are easy to make.
If you want to make the type that curves over the water go to an auto wrecker and get four heavy truck leaf springs.
Get them welded together in pairs that reach from side to side of your pond.
Rest the ends on buried concrete footings.
Now you have two curved steel bars over your pond.
What you attach to the top of those is up to you and your imagination.
I used cedar planks completely hiding the steel springs making the bridge appear suspended in the air.
It was cool.
Last time I saw it it was 12 years old and still perfect.

There is no reason that with a sheet of wire mesh and some rebar you couldn't deck these springs with a thick tufa.
If the ends are fastened on firm footings the springs will support tons without moving.

Mimi, I would not attempt to create a tufa bridge, especially in your zone. Been to St. Paul and it is an ice block in the winter! Tufa is not as strong as concrete, but I do think that tufa reacts to freeze thaw alot better then concrete. Even so, tufa wears down with just walking on it. I made a stepping stone and placed it at a week long art show where it would receive alot of traffic. You should see what happened to it. Lets say there is no top pattern left!

Jo

Hi Jo
I disagree and I'm the most paranoid guy here when it comes to avoiding freeze thaw damage.
An arched bridge of strong tufa would allow constant runoff for melting ice. If the top is sealed with a good zylene concrete sealer even surface damage could be avoided.
Also natural wear on tufa can be very attractive.
And if you don't like the wear top coating with a 1/2 layer of new tufa is a very easy thing to do.

A tufa bridge would require no more maintanance than a wood bridge, and probably less.

And built on top of truck leaf springs it would be easy to do.

Mimi-

Why couldn't you make the side supports out of tufa/concrete, shaping them to resemble boulders or whatever strikes your fancy, leaving a shelf of sorts on either side to hold the area that would get the most wear. Placing wooden planks down the middle where the foot traffic would be greatest would take care of the drainage problem and the planks could be replaced as need be.

It's a thought.

Jo

Thanks for all your input. Tufaenough, I had to google for truck leafs, I had no idea what they were. But i must say that is a brilliant idea. Do I need to get "matching" leaf springs or are they all standard sized? I do agree with you about freeze thaw. If cement is properly enforced it should be fine and sealing it would make it wear evn better. The bridge would get VERY LITTLE traffic so that doesn't concern me much. I do really like the idea of of wood planks, Jo. I think it would add a lot of interest to it. Well, off to the auto graveyard for me (then to see Papa to do some welding) thanks so much. If all is well I will post pics :+)

Hi Mimi
Those springs come in all lengths and widths. Just figure out how long you span is and choose accordingly. They should be really cheap. If you are going over 8 feet you might need 3 on each side.
You can use a couple lengths of steel as well but springs already have the curve and they usually have hundreds just laying around at the wreckers.
Good luck!