To extend previous research done at the FHWA's Hydraulics Research Laboratory on the hydraulic performance of bottomless culverts.

This study will focus on three hydraulic attributes for bottomless culverts: * Fixed bed tests will be conducted to measure pre-scour conditions, which are the basis for the methodology proposed in the earlier study to preduct scour. * Submerged entrance conditions will be tested for both fixed bed and moveable bed conditions. * Entrance loss coefficients will be determined for prescour and scoured conditions. * Design coefficients for riprap stability at the culvert entrance will be evaluated and reavised as necessary. * Cross vanes near the culvert entrance, in the approach flow will be tested as a countermeasure for culvert scour. Detailed velocity distributions will be measured at the culvert entrance using advanced techniques to test assumptions made in GKY&A's and MD DOT methodologies.