Parabolic bridge

"I will build extremely light and strong bridges, which will be easy to transport and will serve to chase enemies or run from them. And I will also build secure and invulnerable bridges, easy to be placed and removed"

This one span bridge has a parabolic profile and is secured to one of the two banks with a large vertical hinge. It is moved with ropes and hoists, aided by wheels or metal rollers that facilitate the sliding motion. It is also equipped with a counterweight tank, which balances the structure and helps manoeuvres when the bridge is suspended before being laid down on the opposite bank.
Codex Atlanticus, sheet 855
1480-90