Influence of Wingwall Configuration on Outlet Scour at Bottomless Box Culverts

The purpose of this study was to determine what influence the inclusion of wingwalls, of various types, located on the downstream side of a bottom box culvert, have on the magnitude of the resulting scour hole depths. Seven laboratory experiments were conducted with constant hydraulic conditions, each one with a different outlet configuration, and the resulting scour hole depths were measured. The results of the experiments showed the deepest scour holes occurred when there were either no wingwalls or when wingwall configurations were either at 45 degree angles or had a truncated circular beveled configuration. Conversely, the shallowest scour holes occurred when there was either a smooth wingwall placed on an 8 degree angle or a streamlined beveled wingwall configuration. Boundary roughness of the wingwall was also shown to influence the resulting scour hole depth.