English: Retractable Bridge (colloquially referred to as a 'rolling bridge') - Barry Docks. This rare example of a hydraulically-operated retractable bridge built by the Darlington Carriage and Wagon Works in the 1880s has been permanently pulled aside and lies rotting on the quay. Along with its control building (often referred to as a 'signal box'), it is now a listed structure. It is one of over 1,450 movable bridges that I have recorded for my historical website www.movablebridges.org.uk. There were at one time two of these bridges in Barry Docks, plus a swingbridge and a submersible bridge (floatable caisson), the latter to seal off the drydock parallel with the Lady Windsor lock. All bore a single line rail track for transits across the south side of the docks except for the swingbridge which permitted road/rail traffic to cross the narrow ship corridor between Nos.1 & 2 docks but except for the swingbridge, were little used after World War II.