How does drainage quality affect pavement design?

Drainage coefficient m reduces or increases effective structural contribution. Poor drainage (m=0.80): 20% penalty. Excellent drainage (m=1.40): 40% bonus. Using geocomposite drainage layer can reduce total pavement thickness.

What minimum layer thicknesses are required?

AASHTO minimums based on traffic level. Low volume: AC 50mm (2in), crushed stone base 100mm (4in). High volume: AC 150mm+ (6in+), base 200-300mm. Minimum thicknesses ensure constructability and structural integrity.

Can I reduce AC thickness by increasing base thickness?

Yes, within limits. SN constraint must be met. Thicker granular base is cheaper than AC but has lower coefficient (0.14 vs 0.44). Optimal balance depends on material costs. Minimum AC thickness prevents fatigue cracking.

Pavement Structural Number Calculator

Calculate pavement structural number SN = a1D1 + a2D2m2 + a3D3m3. Drainage coefficients m: excellent m=1.40, good 1.20, fair 1.00, poor 0.80. Minimum layer thicknesses. SN to thickness conversion.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Calculate pavement structural number SN = a1D1 + a2D2m2 + a3D3m3. Drainage coefficients m: excellent m=1.40, good 1.20, fair 1.00, poor 0.80. Minimum layer thicknesses. SN to thickness conversion. Use the structural number result to inform your clinical assessment.

Related Calculators

Pavement Design

Engineering

IRI Roughness

Engineering

Traffic Flow

Engineering

Pavement Structural Number Calculator

How to Use

Related Calculators

Frequently Asked Questions

How does drainage quality affect pavement design?

What minimum layer thicknesses are required?

Can I reduce AC thickness by increasing base thickness?