Abstract: A gangway bellow includes an outer bellow presenting corrugations forming a plurality of valleys presenting each a valley top portion facing upwardly and connected at each end to a valley top corner forming a junction between the valley top portion and a respective bellow side. The gangway bellow further includes at least one drainage channel so that liquid accumulating into at least one of the valley top portions flows through the at least one drainage channel along the respective bellow side.

Abstract: A revetment made wholly or predominantly from concrete, useful to line a stream bed, having upper and lower surfaces, and having upstream and downstream edges, has, for each upstream edge, an upstream bevel, which intersects the upper surface and which intersects said upstream edge. The revetment has an array of holes extending between the upper and lower surfaces. Each hole has a lateral wall flaring outwardly in a downstream direction from a circular mouth at the lower wall to an elongate mouth at the upper wall. Each upstream or downstream edge is stepped so as to define an upper or lower flange. In an assembly of such revetments, which may be connected to one another, as by cables, each of at least some of the upper flanges overlies one of the lower flanges.