Beginning in 1985, both HMNB Clyde and the Royal Naval Armaments Depot Coulport at Faslane underwent extensive redevelopment in preparation for the "Vanguard" class submarines and Trident II missiles. Rosyth dockyard also underwent significant redevelopment. The work included enhanced "handling, storage, armament processing, berthing, docking, engineering, training and refitting facilities" at an estimates cost of £550 million. Similarly, due to the huge scale of the "Vanguard"-class design, the Devonshire Dock Hall was built specifically for the construction of the boats. Construction started in 1982 and was completed in 1986.