What movable bridge did Leonardo da Vinci design with a counterweight for rapid deployment?

Leonardo da Vinci designed a revolving bridge with a counterweight for rapid deployment.

The bridge was intended for military use and could swing or pivot into position across a waterway. Leonardo’s design included a counterweight to make the long structure easier to move and to help balance it while it was being positioned. Wheels or rollers could assist the operation on the bank.

This arrangement offered strategic advantages. A force could cross quickly, then remove or reposition the bridge, making it harder for an opponent to follow. The design shows Leonardo approaching bridge building as a problem of controlled motion as well as structural strength.

A revolving bridge is different from a conventional drawbridge. A drawbridge normally pivots upward from one end, while Leonardo’s concept turns horizontally around a pivot. It is also distinct from a self-supporting bridge, another Leonardo design that relied mainly on interlocking beams rather than a rotating mechanism.