Design and set out curves with confidence. Choose your method, then review every key parameter. Export results, share with crews, and reduce rework today.
| Units | R | Δ | T | L | LC | E | M |
|---|---|---|---|---|---|---|---|
| Metric | 300 m | 40° | 109.19 m | 209.44 m | 205.21 m | 19.25 m | 18.09 m |
Horizontal curves connect tangents smoothly, controlling vehicle path, drainage flow lines, and right-of-way use. In roadwork, a small change in radius can shift curb returns, widening, and utility conflicts. For building sites, curves govern access drives and fire routes where swept path and clearances are critical.
The calculator reports radius (R), central angle (Δ), tangent length (T), arc length (L), long chord (LC), external distance (E), and middle ordinate (M). These values define the curve footprint and allow quick checks against plan callouts. Output units follow the chosen system for consistent field notes.
Projects rarely provide the same knowns. Some drawings specify R and Δ, while others give degree of curve or a measured curve length. The available modes let you solve from Radius + Delta, Degree + Delta, Radius + Length, Tangent + Delta, or Long Chord + Delta. This reduces manual rearranging and transcription errors.
When a PI station is entered, the calculator derives PC and PT stations using the tangent length and arc length. That creates clear control points for layout: set hubs at PI for alignment, then establish PC for curve start and PT for curve end. Stations are formatted in common “plus” notation for crews.
The setout table generates points from PC to PT at a chosen arc interval. For each point it reports arc distance, station, central angle, and deflection angle. Deflection angles are useful with a total station from the tangent, while X and Y offsets support coordinate-based layout and quick sanity checks during field verification.
Common construction intervals are 20 m for roadway centerlines and 50 ft for conventional surveying, but tighter curves may require shorter spacing. The calculator automatically adds a final sub-chord if the curve length is not an exact multiple of the interval. Keeping consistent rounding across field sheets helps avoid cumulative station drift.
The optional speed check estimates a minimum radius using design speed, superelevation (e), and side friction (f). Enter e as a percent or decimal and f as a decimal or percent. The output flags whether the computed radius meets the basic screening value, supporting quick feasibility checks before deeper standards review.
Before issuing stakes, verify Δ matches the plan intersection angle and confirm units and station bases. Cross-check T and L against any plan tables and ensure PC/PT stations fall within project limits. Export CSV for staking sheets and the PDF for submittals, enabling traceable geometry during inspections and as-built preparation.
Δ is the total central angle of the curve between tangents. Deflection angle is the angle turned from the tangent to a chord or point on the curve, commonly taken as half the central angle to that point.
Use it when plans specify degree of curve rather than radius. Select the correct definition (arc or chord, 100 ft or 30 m) to match the drawings, then enter Δ to compute radius and all other values.
The table steps along the curve by arc interval. It also reports the corresponding chord for each step and provides X and Y offsets. If your practice requires chord increments, use the chord values as guidance.
You can enter stationing as a plain number or plus format such as 10+000. The calculator converts it internally to a continuous distance, then formats PC and PT back into plus notation using the selected unit system’s station base.
The PDF is a simple text report generated directly in the file, suitable for sharing and recordkeeping. For full staking data, the CSV export provides the complete setout table with numeric precision and station fields.
Use values specified by your project or governing standards. Typical superelevation might range from 2% to 8%, and side friction depends on speed and surface. The calculator performs a screening check, not a full design approval.
If the curve length is not an exact multiple of the chosen interval, the remaining distance is added as a final sub-chord point. This keeps the table aligned with PT while maintaining consistent spacing for most points.
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.