AIRPORT PLANNING MANUAL 7.7. RIGID PAVEMENT REQUIREMENTS, PORTLAND CEMENT ASSOCIATION DESIGN METHOD This method has a chart that has been prepared with the use of the Westergaard Equation in general accordance with the procedures outlined in the 1955 edition of “Design of Concrete Airport Pavement” published by the Portland Cement Association, 33 W. Grand Ave., Chicago 10, Illinois, but modified to the new format described in the 1968 Portland Cement Association publication, “Computer Program for Concrete Airport Pavement Design” by Robert G. Packard. The following procedure is used to develop rigid pavement design curves such as those shown in the chart: • Oncethescaleforthepavementthicknesstotheleftandthescaleforallowableworkingstresstothe right have been established, an arbitrary load line is drawn representing the main landing gear maximum weight to be shown. • All values of the subgrade modulus (k-values) are then plotted. • Additional load lines for the incremental values of weight on the main landing gear are then established on the basis of the curve for k=300, already established. EFFECTIVITY: ALL Section 7 Page 7-11 Dec08/03 b-apm1346