Road Camber Calculator

Work out road camber instantly with clear inputs, formula shown and shareable results.

About Road Camber Calculator

Camber sheds water off the carriageway. On a crowned section the fall applies from the centre to each edge, so the crown rise is half the width times the crossfall. Sealed bituminous surfaces use 2 to 2.5 percent, gravel 3 to 4 percent and earth roads up to 5 percent, because rougher surfaces need more slope to drain.

Formulas

Crown rise

Rise = half width x crossfall for a crowned section, full width for a one way crossfall

Camber ratio

Camber as 1 in N = 1 / crossfall as a fraction

Worked example

With the default values below, Road Camber Calculator returns Rise from edge to crown of 87.5. Change any input above and every figure here is recalculated in your browser.

Inputs used

Carriageway widthminimum 1 m: 7 m
Camber or crossfallaccepts 0.5–8 %: 2.5 %
Cross section typeone of Crowned both ways from the centre, One way crossfall: Crowned both ways from the centre

Results

Rise from edge to crown: 87.5 mm
Camber expressed as one in: 40.0
Total fall across the width: 87.5 mm
Drainage assessment: Appropriate for a sealed bituminous surface

Step by step

1Values used
2Crown rise
3Camber ratio
4Rise from edge to crown= 87.5 mm
5Camber expressed as one in= 40.0
6Total fall across the width= 87.5 mm
7Drainage assessment= Appropriate for a sealed bituminous surface

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Crossfall values must follow the road design standard adopted by the authority.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Crossfall values must follow the road design standard adopted by the authority.

Frequently Asked Questions

How is the Road Camber figure worked out?

Rise = half width x crossfall for a crowned section, full width for a one way crossfall. Camber sheds water off the carriageway.

Why not use a steep camber everywhere?

Because it makes vehicles pull toward the kerb, is uncomfortable at speed and complicates the transition into superelevated curves. The minimum that drains reliably is the right answer.

What values do I need to enter?

This calculator takes 3 inputs: Carriageway width, Camber or crossfall, Cross section type. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.