Stopping Sight Distance Calculator
SSD from speed, reaction time and friction — IRC/AASHTO style.
80 km/h needs ~120 m of clear sight — every crest curve, hedge and parked truck is checked against this number. Downgrades stretch it alarmingly (the −G term).
Formula
Stopping Sight Distance Calculator is a free stopping sight distance for surveyors, civil engineers and property buyers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Stopping Sight Distance Calculator
SSD from speed, reaction time and friction — IRC/AASHTO style. The calculation implements SSD = v·t + v²/2g(f ± G) (IRC 66; AASHTO Green Book). 80 km/h needs ~120 m of clear sight — every crest curve, hedge and parked truck is checked against this number. Downgrades stretch it alarmingly (the −G term).
How to use Stopping Sight Distance Calculator
- 1Enter Design speed in km/h.
- 2Enter Perception-reaction time in s.
- 3Enter Longitudinal friction (IRC: 0.40 @ 30 km/h → 0.35 @ 80+).
- 4Enter Grade (+up/−down) in %.
- 5Read Stopping sight distance, Braking component instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Stopping Sight Distance Calculator?
- ✓Implements the standard formula — SSD = v·t + v²/2g(f ± G)
- ✓Reference cited on-page: IRC 66; AASHTO Green Book
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Stopping Sight Distance Calculator use?+
It computes SSD = v·t + v²/2g(f ± G), per IRC 66; AASHTO Green Book. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
80 km/h needs ~120 m of clear sight — every crest curve, hedge and parked truck is checked against this number. Downgrades stretch it alarmingly (the −G term).
Are regional land units exact?+
Conversion factors follow state revenue-department values noted on the tool. Units like bigha and katha vary by region, so always confirm the local factor named in your land records.
Is the Stopping Sight Distance Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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