CBR Calculator

Calculate pavement thickness and subbase design from California Bearing Ratio values — free road engineering tool

Traffic Category

ABCD

Category C (Heavy vehicles 100-250/day)

TA = Equivalent Thickness (cm)

TA = Σ(hi × ai)

hi: layer thickness, ai: equivalence factor

Design CBR

Design CBR Value (%)

Required Equivalent Thickness

Required TA

34.5 cm

Planned TA

35.0 cm

Pavement Layer Composition

Layer	Thickness (cm)	Factor a	TA (cm)
Surface	4	1.00	4.0
Binder	4	1.00	4.0
Upper Base (Crushed Stone)	15	0.80	12.0
Lower Subbase (Crusher Run)	60	0.25	15.0
Total	83	-	35.0

Cross Section

Surface4 cm

Binder4 cm

Upper Base (Crushed Stone)15 cm

Lower Subbase (Crusher Run)60 cm

Subgrade (CBR = 6%)