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Stopping Sight Distance (SSD) is defined as the distance provided on the road before a sharp turn or obstacle to allow a vehicle to come to a complete stop safely. It is a critical parameter in road design and traffic engineering.
The calculator uses the Stopping Sight Distance formula:
Where:
Explanation: The formula accounts for both the distance traveled during the driver's reaction time and the braking distance required to bring the vehicle to a complete stop.
Details: Accurate SSD calculation is crucial for road safety design, determining safe speeds, and ensuring adequate visibility distances for drivers to react to obstacles or changes in road conditions.
Tips: Enter vehicle speed in meters per second, break reaction time in seconds, and design coefficient of friction. All values must be positive numbers greater than zero.
Q1: What is a typical break reaction time?
A: For most drivers, break reaction time ranges from 1.5 to 2.5 seconds, with 2.5 seconds being the standard value used in many road design guidelines.
Q2: How does friction coefficient affect stopping distance?
A: Higher friction coefficients result in shorter stopping distances as they provide better grip between tires and road surface.
Q3: What are typical friction coefficient values?
A: Friction coefficients typically range from 0.3 (wet pavement) to 0.7 (dry pavement) for most road surfaces.
Q4: Why use meters per second instead of km/h?
A: The formula requires consistent SI units, and m/s provides more precise calculations for engineering applications.
Q5: How does vehicle speed affect stopping distance?
A: Stopping distance increases quadratically with speed - doubling the speed quadruples the stopping distance.