Z Caisson at Rosyth Royal Dockyard

Z Caisson is a seismically designed concrete dock gate constructed and installed at Rosyth Royal Dockyard in 1995 in support of the Royal Navy's nuclear submarine refit programme. The first such structure in the UK, it received the British Construction Industry Award for small projects in 1996 in recognition of its design and construction. The caisson is a gravity structure which rests on a prepared gravel bed at the dock entrance and seals against the dock jambs via a proprietary rubber ‘lip seal’. It therefore applies negligible loading to the dock structure, which would otherwise have required strengthening for the seismic case.