Design Parameters
km/h
sec
Roadway Conditions
-
%
Sufficiency Check
Required vs AASHTO Minimum SSD--
ExceedsAASHTO MinSafe Margin
Awaiting Input
Analysis Results
Perception-Reaction Dist.
--m
Braking Distance
--m
AASHTO Min SSD (Level)
--m
Total Required SSD
--m
Reference Formulas
AASHTO Stopping Sight Distance:
SSD = dpr + dbr
Perception-Reaction Distance:
SI: dpr = 0.278 · V · t
US: dpr = 1.47 · V · t
Braking Distance (Grade Adjusted):
SI: dbr = V² / [254 · (f ± G)]
US: dbr = V² / [30 · (f ± G)]
G = grade (decimal), + for upgrade, - for downgrade. V in km/h (SI) or mph (US).
Roadway Profile & Stopping Maneuver
Distance Breakdown
SSD vs Speed Safety Envelope