Plan crest geometry for safe access and inspection. Choose simple width or segment inputs today. Get totals, subtotals, and downloads in one view instantly.
| Scenario | Method | Inputs | Output (m) |
|---|---|---|---|
| Preliminary layout | Simple | Valley width 180, Left 10, Right 12 | 202.00 |
| Segmented alignment | Segments | Straights: 40, 55, 30; Curves: R=120, θ=30 | 187.83 |
| Curved crest road | Segments | Straights: 60; Curves: R=200, θ=45 and R=150, θ=20 | 248.33 |
Accurate crest length starts with reliable horizontal control. Use recent survey or design drawings to define the crest centerline, abutment tie‑ins, and any transitions to access roads. Record the crest elevation reference used for the width measurement so the estimate matches the final grading line. Small shifts in alignment can change length, quantities, and safety hardware needs. For rehabilitation projects, validate as-built offsets and confirm if the crest includes sidewalks, curbs, or berms that affect geometry. in plan.
The simple method is best during concept selection when the crest is nearly straight. It adds valley width at the crest line plus allowances for abutment tie‑ins, guardrails, and roadway transitions. The segmented method is preferred for detailed design because it mirrors plan geometry: add straight tangents and compute arcs from radius and central angle. Use one consistent unit system for every input.
For curves, confirm whether the radius is measured to the crest centerline or to an edge of roadway. If the radius comes from roadway geometry, apply it consistently across all curves. Keep angles in degrees and ensure they represent the central angle of the arc actually built. When long curves are approximated by multiple arcs, enter each arc separately to reduce rounding and layout error.
Allowances should reflect real construction details: abutment contact zones, parapet transitions, spillway approach connections, and turning radii for maintenance vehicles. Add additional length where crest widening, laydown areas, or traffic control is planned. If tolerances are tight, include a contingency percentage and document why. This supports budget control and reduces change orders caused by underestimated crest work.
Exporting results is most valuable when paired with traceable inputs. Save a CSV for quantity takeoffs and a PDF for design check packages, then attach the crest stationing note that matches the drawings. During review, verify that straight segments sum to the plan tangents and that each curve uses the correct radius and angle. Recalculate after alignment revisions and keep a dated record for audit.
It is the plan length along the dam crest alignment. It supports estimating grading, pavement, barriers, and inspection access quantities for the crest corridor.
Use it for early planning when the crest is nearly straight and you only know valley width and abutment tie‑in allowances. Switch to segments once alignment geometry is available.
Provide the curve radius and the central angle in degrees for the crest centerline. The calculator converts that to arc length using 2πR × (θ/360).
Base them on tie‑in details, roadway transitions, parapet or guardrail terminations, and constructability needs. Document the reasoning so reviewers can confirm the assumptions.
No. Select one unit system and enter every length in that unit. The output and exported files will use the same unit you selected.
Group minor tangents, or enter the dominant segments and arcs, then add a contingency and note the simplification. For final design, use CAD stationing as the reference.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.