Inputs
total 18-kip equivalent loads
50–99.9
flexible 0.40–0.50
psi (resilient modulus)
serviceability loss
Layer Coefficients & Drainage
~0.44 typical HMA
crushed agg ≈ 0.14
granular ≈ 0.11
0.80–1.20
in (heuristic)
AASHTO 1993 equation
- log10W18 = ZR·So + 9.36·log(SN+1) − 0.20 + log(ΔPSI/2.7)/[0.4 + 1094/(SN+1)5.19] + 2.32·log(MR) − 8.07.
- Solver iterates SN to satisfy equation.
- Layer split: SN1* = a1·D1; SN2* = a1·D1 + a2·m2·D2; SN3* = total.
- Choose D1 ≥ D1* / a1; etc. Conservative integer rounding.
Results
ZR (from R)—
log10 W18—
Required SN—
| Layer | a · m | D (in) | SN contribution |
|---|
Provided SN—