This report describes the instrumentation and measurements of settlements and pressures on two box culverts in Clark County, Kentucky, designed without the imperfect trench -- one for yielding and one for unyielding foundation conditions. The structures were primarily instrumented for comparison with three structures previously constructed in McCreary County, which were designed using the imperfect trench method. Pressures on the two structures in Clark County generally exceed the product of the unit weight of the overlying material and its height. The pressures on the culverts in McCreary County appear to be lower than expected -- indicating that the imperfect trench is generally effective in reducing loads.

Report Date


Report Number

No. 431

Digital Object Identifier



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