Calculator Inputs
Example Data Table
| Segment | Type | Inputs | Horizontal Length (m) | Grade (%) | 3D Length (m) |
|---|---|---|---|---|---|
| 1 | Straight | Length = 250 | 250.000 | 2.00 | 250.050 |
| 2 | Curve (arc) | Radius = 60, Angle = 90° | 94.248 | 4.00 | 94.323 |
| 3 | Straight | Length = 180 | 180.000 | 1.50 | 180.020 |
| Totals | 524.248 | — | 524.393 | ||
Formula Used
- Straight segment (horizontal): Lh = Length
- Curve segment (horizontal): Lh = Arc, or Lh = π × R × (θ / 180)
- Grade-adjusted (3D) length: L3D = Lh × √(1 + (g/100)²)
- Total length: ΣLh and ΣL3D across all segments
- Stationing: cumulative horizontal distance along the alignment
How to Use This Calculator
- Select units and choose the number of alignment segments.
- For each segment, pick Straight or Curve.
- Straight: enter its horizontal length and optional grade.
- Curve: enter arc length, or radius and central angle.
- Press Calculate Length to show the results box.
- Use the export buttons to download a CSV or PDF report.
Segment-based length modeling for access roads
Access roads are rarely one straight line. Breaking the alignment into straights and curves lets you estimate corridor length early, then refine it as survey control improves. This calculator sums each segment’s horizontal contribution and also reports a grade-adjusted 3D length to reflect sloped terrain. On active construction sites, this structure supports quick checks for equipment delivery, temporary easements, and gate placement, reducing rework when the alignment shifts during late approvals reviews. Use the horizontal total for stationing and the 3D total for rough quantities that depend on travel distance.
Curve geometry and arc length consistency
For curved segments, the tool accepts either an explicit arc length or the radius-and-angle method. Arc length is computed as π × R × (θ/180), where θ is the central angle in degrees. This supports typical design notes such as “R=60 m, Δ=90°” and produces a comparable length basis for culverts, widening, and safe-speed checks along the approach.
Grade adjustment for realistic travel distance
Grade does not change stationing, but it changes the true path length over the ground. The calculator uses L3D = Lh × √(1 + (g/100)²), where g is the segment grade in percent. On moderate grades the difference is small, yet it becomes useful for haul planning, fuel estimates, and time-on-route comparisons between alternate access corridors.
Stationing outputs to support field layout
Each segment row shows start and end station based on cumulative horizontal length. In metric mode, stationing is displayed as 1+000.00 increments; in imperial mode it uses 1+00.00 style. This mirrors common drawing conventions and helps crews relate the estimate to stakeout points, entrance gates, turnouts, and temporary construction limits.
Exportable reports for review and documentation
CSV and PDF exports capture totals, segment breakdown, and grade statistics for quick review. Use CSV for estimating sheets and scenario comparisons, and PDF for sharing with clients, inspectors, and subcontractors. Keep inputs consistent with your selected unit system, and update segments as alignment decisions change.
How many segments should I use?
Use the fewest segments that still match the alignment shape. Start with 3–6 for conceptual planning, then increase as you add tangents, curves, or access spurs. More segments improve clarity without changing the underlying math.
When should I enter arc length instead of radius and angle?
Enter arc length when it is known from CAD, corridor modeling, or as-built measurements. Use radius and angle when you have design notes or a plan set listing curve parameters. If arc length is filled, it takes priority.
Does grade affect stationing?
No. Stationing is based on horizontal length along the alignment. Grade is used only to compute a 3D distance that better reflects ground travel. Report both values when quantities depend on movement over sloped terrain.
What grade value should I enter for rolling terrain?
Enter the average grade for that segment, using a sign if you want to reflect uphill or downhill direction. The calculator reports an average absolute grade for readability. For highly variable terrain, split into shorter segments.
Can this replace detailed roadway design software?
It is best for planning and checking. Detailed design still requires full geometry, cross-sections, drainage, and standards review. Use this output to validate early assumptions, compare alternates, and prepare preliminary documentation.
Why do my totals differ from map measurements?
Differences usually come from curves, scale, or elevation effects. Map tools often measure along a simplified path, while this calculator uses explicit curve geometry and optional grade adjustment. Confirm inputs and segment definitions for consistency.