Afsluitdijk

The Afsluitdijk (Dutch: [ˈɑfslœydɛik] ^ⓘ; West Frisian: Ofslútdyk; Dutch Low Saxon: Ofsluutdiek; English: "Closure Dyke") is a major dam and causeway in the Netherlands. It was constructed between 1927 and 1932 and runs from Den Oever in North Holland province to the village of Zurich in Friesland province, over a length of 32 kilometres (20 mi) and a width of 90 metres (300 ft), at an initial height above Amsterdam Ordnance Datum of between 6.7 metres (22 ft) along the section at Friesland, and 7.4 metres (24 ft) where it crosses the deep channel of the Vlieter. The height at the greater sea depths west of Friesland was required to be a minimum of 7 metres everywhere when originally constructed.

Increases to the height of the Afsluitdijk have been made several times since 1958, when height increases were undertaken during regular maintenance periods as a result of the North Sea Flood of 1953, with the section between the Stevinsluizen and Lorentzsluizen sluice complexes seeing the crest level raised to 7.8 metres. Major upgrade works commenced in 2019, with one of the design conditions being that only limited wave overtopping during the design storm condition be permitted. The design proposed by the successful contractor to meet this criterion will see a further increase in the height of the dam, by approximately 2 metres.

The Afsluitdijk is a fundamental part of the larger Zuiderzee Works, damming off the Zuiderzee, a salt water inlet of the North Sea, and turning it into the fresh water lake of the IJsselmeer. It is a major landwinning project and a quicker road-connection between the North and West of the Netherlands.

The motorway on the Afsluitdijk was the initial demonstration site for a 130 km/h (81 mph) speed limit in the Netherlands.