log10(W18)=ZR⋅S0+9.36⋅log10(SN+1)−0.20+log10[ΔPSI4.2−1.5]0.40+1094(SN+1)5.19+2.32⋅log10(MR)−8.07log base 10 of open paren cap W sub 18 close paren equals cap Z sub cap R center dot cap S sub 0 plus 9.36 center dot log base 10 of open paren cap S cap N plus 1 close paren minus 0.20 plus the fraction with numerator log base 10 of open bracket the fraction with numerator cap delta cap P cap S cap I and denominator 4.2 minus 1.5 end-fraction close bracket and denominator 0.40 plus the fraction with numerator 1094 and denominator open paren cap S cap N plus 1 close paren to the 5.19 power end-fraction end-fraction plus 2.32 center dot log base 10 of open paren cap M sub cap R close paren minus 8.07 Key Design Variables W18cap W sub 18
(Design Traffic): Total expected 18,000-lb over the design period. ZRcap Z sub cap R aashto flexible pavement design excel spreadsheet
(Resilient Modulus): A measure of the in psi. 2. Converting SN to Layer Thicknesses log10(W18)=ZR⋅S0+9
Once the spreadsheet calculates the required , you must select layer thicknesses ( ) that provide equivalent strength. The structural capacity is calculated as: Converting SN to Layer Thicknesses Once the spreadsheet
AASHTO Flexible Pavement Design: The Ultimate Guide to Excel Spreadsheets