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The horizontal distance from the roadway's centerline crown to the edge of pavement.
For a symmetric crown, this is half the total paved width.
The target drainage cross-slope from centerline to edge, as a percentage.
2% is a commonly used target cross-slope for roadway drainage design.
Edge elevation drop
2.76 in
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Roadway Crown Cross-Slope Calculator: 2.76 in — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Edge elevation drop = half-width × target cross-slope percentage, the standard method for establishing a roadway crown's drainage slope from centerline to edge of pavement
Inputs used
- Half Roadway Width (Centerline to Edge)
- 11.5 ft
- Target Cross-Slope (%, Commonly 2%)
- 2
What this calculation does not cover
- The edge drop is worked as one straight gradient from crown to edge, so where a crown is built as a curve rather than two flat planes only the edge point matches — the pavement at intermediate offsets sits higher, with less drop, than a straight interpolation implies.
- A single half-width and a single cross-slope stand in for both sides of the road, so an asymmetric crown, a widened lane, or a different slope left and right has to be run twice and the two drops read separately.
- Longitudinal grade is absent from the arithmetic: where the road also falls along its length, water leaves the surface on a diagonal path and the true surface gradient is the resultant of the two slopes rather than the cross-slope alone.
- The cross-slope field accepts 1% to 4% only, so a superelevated curve banked beyond that band, or a deliberately flatter section, cannot be entered here.
- Half-width is read as a horizontal plan distance, so a width tape-measured along the crowned surface instead of taken off the drawing is fractionally long and inflates the drop by a correspondingly small amount.
- The figure describes the finished pavement surface between centreline and edge of pavement — course thicknesses, subgrade profile, and any gutter pan or shoulder break beyond that edge sit outside it.
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Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-05 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Edge elevation drop = half-width × target cross-slope percentage, the standard method for establishing a roadway crown's drainage slope from centerline to edge of pavement
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