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Road Camber — by Surface Type

Cross-slope of road carriageway for surface drainage
See also📖 IRC SP 13 / IRC 86🔗 IRC SP 13🔗 IRC 86🔗 IRC 36🧮 RCC Design📒 Handbook Topic
1 : 50
for cement concrete
WBM 1 : 33 · bitumen 1 : 40 · earth 1 : 25
ROAD CROSS-SECTION — CAMBERSUB-BASEBASEWEARING1 : 507.0mSURFACE: CEMENT CONCRETE1 : 50 CEMENT CONCRETE ROAD
Primary value1 : 50 for cement concrete (WBM 1 : 33 · bitumen 1 : 40 · earth 1 : 25)
Applies toInternal driveways and approach roads in townships · Compound / society roads up to 7 m wide · Light-traffic urban roads (residential layouts)
ExceptionsCement concrete (smooth)1 : 50 (2.0%)
Bituminous (modern asphalt)1 : 40 (2.5%)
Water-bound macadam (WBM)1 : 33 (3.0%)
Earth / unpaved surface1 : 25 (4.0%)
Heavy-rainfall beltUse steeper limit
High-speed road (≥ 100 km/h)Reduce camber by 10–15% for lateral stability
Measured asVertical drop from the crown of the carriageway to the edge, divided by half the carriageway width. Expressed as ratio (1 : N) or percentage. Both sides drain to side drains.
SourceIRC SP 13 / IRC 86Camber design tables
✓ Verified

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Why this matters

Camber is the entire reason a road sheds water — too little and puddles form on the surface, accelerating cracking; too much and vehicles drift outward in fast turns. The IRC table maps surface roughness to ideal camber: smoother surfaces (cement) need less drop because water flows easily; rougher surfaces (earth) need steeper drop to overcome surface tension and absorption.

Typical practice

Most internal township roads in India are 7 m wide with a 1:50 cement concrete surface — that's a 70 mm crown rise from edge to centre. A 4 m bitumen driveway uses 1:40 with a 50 mm crown. Side drains catch the runoff at the edge.

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