Are you sure those bridges aren't counter-weighted? I don't believe I've ever seen a drawbridge that wasn't. Moving a counter-weighted something-heavy up and d

Are you sure those bridges aren't counter-weighted? I don't believe I've ever seen a drawbridge that wasn't. Moving a counter-weighted something-heavy up and down is a distinctly different physics problem (that closely resembles moving it back and forth horizontally) than moving an unattached something-heavy up and down.