I would like to build an arched bridge over our stream. I need to span about 20 feet and think a rise of about 2-3 feet would be sufficient. Has anyone seen plans on how to do this?

This bridge will be for foot traffic.. and maybe a riding mower. I plan to build it out of wood. It's an aesthetic delight as much as a functional device.

It's the curve in the support structure that I could use some direction on. I suppose I could build laminated beams that attach to sunken posts. That's why a set of plans would be helpful.