and slopes of various properties in various types of terrain the headwall structures 10 can accordingly be manufactured in various standard sizes and configurations to meet a range of expected conditions and requirements or may be individually designed as required note that the choice of frontal area of the front brace panels 42 44 is particularly important as these panels 42 44 lend stability to the installed unit because once the headwall 10 is in place bank slope backfill overlaps the front brace panels 42 44 thereby anchoring the headwall 10 in place in addition the shaping especially of the side brace panels 22 23 can be selected to assist in funnelling the water flow minimizing turbulence by cooperating with the sidewall wings 20 and 21 to provide a gradual tapering of flow cross section as will be seen in fig8 a second preferred embodiment of a headwall according to the invention generally indicated as 50 differs from the first embodiment previously described in that interior wall surfaces of sidewall wings 32 33 are generally concave and the top edges of the sidewall wings 32 33 are generally arcuate the back wall 30 of the headwall 50 containing the spigot 31 continues to be planar but the sidewall wings 32 and 33 are generally cylindrically shaped or otherwise suitably curved the sidewall wings 32 33 with the headwall 50 may instead together form a single curved continuum if desired side brace panels 34 and 35 similarly may optionally be formed with a generally cylindrical or other curvature such curvature assists in funnelling the flowing water over the tray 37 the top flanged.