For many years, engineers have sought a simplified method for determining the strength requirements for underground conduits under various conditions of bedding and backfilling. Methods of installation and the general lack of a uniform design criteria tended to restrict the usefulness of rigid pipe culverts. With the advent of the interstate construction program and the increased mileage of highways meeting high design standards, the number of pipe culverts installed under high fills was significantly increased. This, of course, accented even more so the need for a more straightforward criteria for design and installation of rigid pipe in order that maximum utilization of pipe strengths might be realized and that settlement in the roadway surface near the installation might be minimized. In an effort to satisfy the needs for a simplified design method for rigid pipe, the Bureau of Public Roads in cooperation with Professor M. G. Spangler of Iowa State College and the American Concrete Pipe Association initiated a study of reinforced concrete pipe design and installation procedures. As a result of this study, a stylized, rational criterion was developed and distributed to the various state highway agencies as B. P. R. Circular Memorandum 22-40, dated April 4, 1957.

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Report Number

No. 225

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