Pressure and design analyses of five reinforced concrete box culverts are presented. Three of the culverts were constructed with the imperfect trench. Measured pressures on the culverts are compared to pressures predicted by the theories of Marston, Spangler, and Castes. Also, comparisons are made between measured pressures and calculated design pressures using AASHTO's Standard Specifications for Highway Bridges, 1.2.2(A). It is noted that the imperfect trench is, apparently, effective in reducing pressures on the top slab. The AASHTO design formulas underestimated the pressure on the top slab of the culverts without the imperfect trench.

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No. 491

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The contents of this report reflect the views of the author who is responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Bureau of Highways or Federal Highway Administration. This report does not constitute a standard, specification, or regulation.