Shell pavement design method: Difference between revisions

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The '''Shell pavement design method''' was used in many [[countries]] for the design of new [[asphalt]] [[road]] [[pavements]].<ref>[https://trid.trb.org/view/60936 Asphalt pavement Design - The Shell Method] </ref>. It was the first mechanistic design method, providing a procedure that was no longer based on codification of historic experience but instead that permitted computation of strain levels at key positions in the pavement. By analyzing different proposed constructions (layer materials and thicknesses), the procedure allowed a designer to keep the tensile strain at the bottom of the asphalt at a level less than a critical value and to keep the vertical strain at the top of the subgrade less than another critical value. With these two strains kept, respectively, within the design limits, premature fatigue failure in the asphalt and rutting of the pavement would be precluded. Relationships linking strain values to fatigue and rutting permitted a user to design a pavement able to carry almost any desired number of transits of standard wheel loads.

In such [[structural road design]], the main inputs consist of [[soil]] [[parameter]]s, parameters (thickness and stiffness) for the other road [[Foundation (engineering)|foundation]] materials, and the expected number of times a standard load will pass over. The output of the calculation is the thickness of the asphalt layer.<ref>Shell Pavement Design Manual—Asphalt Pavements and Overlays for Road Traffic. Shell International Petroleum Company, Ltd., London,. England, 1978</ref>