The drain (10) may be fitted in a floor or a roadway. It has a U-section channel with a flat floor (12) and vertical sidewalls (18). The top portions of the sidewalls are joggled outwards, forming shoulders (34) which support longerons (24a,b). The longerons form the long edges of a metal or plastics grating which covers the elongated opening of the drain. The grating has a large number of sloping transverse blades (22) stiffened by additional longerons (24) near its centreline. it may be cleaned by a water jet held at an angle corresponding to the slope of the transverse blades.
