Since the first implementation by Electricite de France on the Goulours dam (France) in 2006, the Piano Key Weir has become a more and more applied solution to increase the discharge capacity of existing spillways. In parallel, several new large dam projects have been built with such a flood control structure, usually in combination with gates. Today, more than 25 Piano Key Weirs are in operation or under construction all over the world. More than 15 years of research and development have enabled detailed investigations of the hydraulic and structural behaviour of the Piano Key Weir...