Pavement Design

AASHTO 1993 Flexible & Rigid Pavement Design — Structural Number, Layer Thickness, Traffic Analysis per AASHTO Guide

🛣️

AASHTO 1993 Pavement Designer

Design flexible and rigid pavements using the AASHTO 1993 empirical method. Calculate Structural Number (SN), layer thicknesses, and verify against traffic loading.

🛣️

Ready to Design

Enter design parameters and click Design Flexible.

🏗️

Rigid Design Ready

🚛 Traffic Analysis (ESAL Calculator)

🚛 Vehicle Class Distribution

Enter % of trucks by FHWA class (4-13). Defaults based on typical highway mix.

⚖️ Axle Load Factors

Equivalency factors per AASHTO 1993 Appendix D. Single/Dual/Tandem/Tridem axles.

📊 Growth Model

Simple compound: N = AADT × 365 × [(1+r)^n - 1] / r. For r=0: N = AADT × 365 × n.

Class 4 (Buses)%

Class 5 (2-Axle SU)%

Class 6 (3-Axle SU)%

Class 7 (4+ Axle SU)%

Class 8 (4-Axle ST)%

Class 9 (5-Axle ST)%

Class 10 (6+ Axle ST)%

Class 11 (5-Axle MT)%

Class 12 (6+ Axle MT)%

🧱 Layer Coefficients & Material Properties

Layer / Material	Typical a₁ (Surface)	Typical a₂ (Base)	Typical a₃ (Subbase)	Drainage m (Good)	Drainage m (Fair)	Drainage m (Poor)	Resilient Modulus (psi)

Surface (AC) a₁

0.44

per inch

Base (Crushed) a₂

0.14

per inch

Subbase (Sand) a₃

0.11

per inch

Drainage m (Good)

1.00

—

Drainage m (Poor)

0.80

—

📐 Structural Number Equation

SN = a₁D₁ + a₂D₂m₂ + a₃D₃m₃
a₁ = surface layer coefficient (AC ≈ 0.44)
a₂ = base layer coefficient (crushed stone ≈ 0.14)
a₃ = subbase layer coefficient (sand ≈ 0.11)
m = drainage coefficient (1.0 good, 0.8 fair, 0.6 poor)
D = layer thickness (inches)
                    

📐 Rigid Pavement Design Equation (AASHTO 1993)

log₁₀(W₁₈) = ZᵣS₀ + 7.35 log₁₀(D+1) - 0.06 + log₁₀[ΔPSI / (4.5-1.5)] 
  + (4.22 - 0.32 pₜ) log₁₀[Sc Cd (D^0.75 - 1.132) / (215.63 J (D^0.75 - 18.42/ (Ec/k)^0.25))]

D = slab thickness (inches)
Sc = modulus of rupture (psi)
Ec = elastic modulus of concrete (psi)
k = modulus of subgrade reaction (pci)
J = load transfer coefficient
Cd = drainage coefficient
                    

Pavement Design

📋 Flexible Pavement Design Results

📋 Rigid Pavement Design Results

🚛 Traffic Analysis (ESAL Calculator)

🧱 Layer Coefficients & Material Properties

📄 Design Report Generator