Use Excel’s native tool (Data > What-If Analysis > Goal Seek). Set the delta cell to a value of 0 by changing your Trial SNcap S cap N
Creating an is crucial for transportation engineers to perform iterative calculations, sensitivity analyses, and optimizations efficiently. 1. The 1993 AASHTO Flexible Pavement Design Equation
): Accounts for variability in traffic predictions and material properties. For flexible pavements, a value of is standard. 3. Serviceability Loss (
: Standard normal deviate corresponding to the selected reliability level. S0cap S sub 0 aashto flexible pavement design excel spreadsheet
To build a functional AASHTO 1993 Flexible Pavement Design spreadsheet, you need to implement the core empirical equation that relates traffic ($W_18$), reliability ($Z_R$), overall standard deviation ($S_o$), structural number ($SN$), and the change in serviceability ($\Delta PSI$).
SN=a1D1+a2D2m2+a3D3m3cap S cap N equals a sub 1 cap D sub 1 plus a sub 2 cap D sub 2 m sub 2 plus a sub 3 cap D sub 3 m sub 3 The goal is to ensure the . Why Use an Excel-Based Tool?
Write out the long mathematical formula for the right side of the equation in an adjacent cell, referencing the SNestcap S cap N sub e s t end-sub cell and all other inputs. Use Excel’s native tool (Data > What-If Analysis
I tested a representative “AASHTO 1993 Flexible Design v4.2” spreadsheet from a public repository:
is determined, you can design the individual layer thicknesses using the following relationship:
Trial Cell: Create a cell for "Trial SN" (e.g., set it to 3.0 initially). The 1993 AASHTO Flexible Pavement Design Equation ):
Here's a simple example of what the spreadsheet might look like:
Go to Data > What-If Analysis > Goal Seek . Set the difference between the left and right sides of the equation to 0 by changing the SNcap S cap N