Stopping Distance Calculator
Calculate the total stopping distance for vehicles, including reaction distance and braking distance
Stopping distance is the total distance a vehicle travels from the moment a hazard is spotted until it comes to a complete stop. It consists of two main components:
- Reaction Distance: The distance traveled while the driver processes the hazard and moves their foot to the brake pedal
- Braking Distance: The distance traveled while the brakes are applied until the vehicle stops completely
The total stopping distance is affected by various factors including:
- Initial speed of the vehicle
- Driver's reaction time
- Road conditions (friction coefficient)
- Vehicle's braking system efficiency
- Weather conditions
- Enter the initial speed in kilometers per hour (km/h)
- Adjust the reaction time (default is 1.5 seconds for average human reaction time)
- Select the appropriate friction coefficient based on road conditions:
- Dry road: 0.7
- Wet road: 0.4
- Ice: 0.1
- Click "Calculate" to see the results
The calculator will display:
- Total stopping distance in meters
- Reaction distance in meters
- Braking distance in meters
The stopping distance is calculated using these formulas:
- Reaction Distance:
- d_r = v × t
- Where v = velocity, t = reaction time
- Braking Distance:
- d_b = v² / (2μg)
- Where v = velocity, μ = friction coefficient, g = gravitational acceleration (9.81 m/s²)
- Total Stopping Distance:
- d_total = d_r + d_b
Understanding stopping distance is crucial for various applications:
- Road Safety: Determining safe following distances between vehicles
- Driver Education: Teaching new drivers about safe driving distances
- Traffic Engineering: Designing road signs, signals, and speed limits
- Vehicle Design: Developing and testing braking systems
- Legal Considerations: Analyzing accidents and determining liability
Why does speed have such a big impact on stopping distance?
While reaction distance increases linearly with speed, braking distance increases with the square of speed. This means that doubling your speed quadruples your braking distance, making it the most critical factor in stopping distance.
How do weather conditions affect stopping distance?
Weather conditions primarily affect the friction coefficient between tires and road. Wet roads can reduce friction by about 40%, while ice can reduce it by up to 90%, dramatically increasing stopping distance.
What is a safe following distance?
A common rule is the "three-second rule": maintain at least three seconds of travel time between you and the vehicle ahead. In adverse conditions (rain, snow, night), increase this to 4-6 seconds.