Sight Distance Calculator
Calculate stopping sight distance (SSD), decision sight distance, and passing sight distance for highway design using AASHTO formulas.
Inputs
mph
sec
%
Results
Stopping Sight Distance
358 ft
Passing Sight Distance
383 ft
Decision Sight Distance656 ft
Brake Reaction Distance165 ft
Braking Distance193 ft
Meets AASHTO Standard1
How to Use This Calculator
- Enter design speed (mph), perception-reaction time (seconds), and friction coefficient.
- Set roadway grade (%).
- Review Stopping Sight Distance (ft), Decision Sight Distance (ft), and Passing Sight Distance (ft).
- Use these values to verify horizontal and vertical alignment clearances meet AASHTO standards.
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