Cardiff Bay barrage locks

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Cardiff Bay barrage locks

Locks have been a feature of Cardiff’s docklands since the 1790s, when a new lock at the mouth of the river Taff resulted in much improved facilities for loading coal into ships. The range between low and high tide along the Bristol Channel is the second highest in the world. Locks retain the dock water at a steady level while allowing vessels to come and go at various states of the tide.

Ships still enter and leave Cardiff docks through a lock near the barrage’s north end. Separate facilities for boats were incorporated into the barrage when it was built in the 1990s. These include three locks, each 40 metres long. Two are 8 metres wide, the other 10.5 metres. Lock gates c.16 metres in height allow boats to pass between the lagoon and sea at all tides.

The outer harbour, on the seaward side, is dredged for boats to approach the lock even at low tide. Boats take 10 to 30 minutes to pass through the locks.

Each lock is crossed by a Bascule bridge, to carry pedestrians and vehicles across. These are lifted for boats to pass. The weight of the bridge deck is counterbalanced by an overhead weight on the opposite side of the pivot.

Five sluice gates control the level of water in the Bay. Each sluice gate is 9 metres wide and 7.5 metres high. The sluices open to maintain the level of the Bay, and close when the estuary level is higher than the Bay to prevent seawater entering the freshwater lake.

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Website of Cardiff Harbour Authority

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