A retractile drawbridge is a rare type of

moveable bridge A moveable bridge, or movable bridge, is a bridge that moves to allow passage for boats or barges. In American English, the term is synonymous with , and the latter is the common term, but drawbridge can be limited to the narrower, historical ...

in which the span is pulled away diagonally on rails. It is a variant of the

retractable bridge A retractable bridge is a type of moveable bridge in which the deck can be rolled or slid backwards to open a gap while traffic crosses, usually a ship on a waterway. This type is sometimes referred to as a thrust bridge. Retractable bridges d ...

. Only four examples are known to exist in the United States. It is believed to have been invented by T. Willis Pratt in the 1860s.

References

{{Bridge-type-stub Bridges