The Total Stopping Distance calculator computes the distance to stop a vehicle based on the initial velocity (vi), reaction time (t) and the a braking coefficient (μ).
Compute Total Stopping Distance
- Choose units (default: kilometers per hour and seconds)
- Enter the initial velocity (v)
- Enter the Reaction Time (t)
- Enter the Braking Coefficient (μ)
Total Stopping Distance (TSD): The calculator returns the distance (TSD) in meters. However this can be automatically converted to other distance units via the pull-down menu.
The Math / Science
The Total Stopping Distance is the sum of the perception-reaction distance and the breaking distance. A common baseline value of reaction time is 1.5 seconds (`t=1.5 s`), and `mu=0.7` is used in stopping distance charts. These values incorporate the ability of the vast majority of drivers under normal road conditions. However, a keen and alert driver may have perception-reaction times well below 1 second, and a modern car with computerized anti-skid brakes may have a friction coefficient of 0.9 - or even far exceed 1.0 with sticky tires.
The breaking distance is one of two components of total stopping distance. The following formula is used to calculate the total stopping distance:
TSD =v•t+v²/(2•μ•g)
where:
- TSD is the total stopping distance
- vi is the initial velocity
- t is the reaction time
- μ is the friction factor
- g is the acceleration due to gravity on earth
Braking Coefficient
The Braking Coefficient is a coefficient of kinetic friction. For accident reconstruction on dry surfaces, a value of 0.7 is often used. This is the default value in this calculator.
Vehicle Calculators
- Approach (Departure) Angle: Computes the maximum angle of a ramp onto which a vehicle can climb without scraping.
- Degree to Percent Grade: Converts a grade to a degree angle.
- Camber angle - Wheel camber (tilt) calculation of angle
- Camber offset - Wheel camber (tilt) calculation of offset
- Breakover Angle: Compute maximum angle that a vehicle can drive over without the ground touching the vehicle's undercarriage.
- Time to Overtake: Computes the time for one object to overtake another.
- Distance to Overtake: Computes distance traveled to overtake another.
- Speed to Overtake: Computes the average velocity to overtake another.
- Distance Traveled: Computes the distance traveled over a period of time.
- Speed from Skid Marks: Estimates the speed of a vehicle based on length of skid marks.
- Braking Distance: Estimates distance to stop a vehicle based on initial velocity and braking coefficient.
- Total Stopping Distance: Computes the distance to stop a vehicle based on the initial velocity, reaction time and a braking coefficient.
- Speed from the Braking Distance: Estimates the initial speed based on the distance to stop a vehicle and the a braking coefficient.
- Used Car Price Comparison: Estimates the better value between two vehicles based on their mileage, cost and expected lifespan (miles).
References
The formula and definition are from Wikipedia (https://en.wikipedia.org/wiki/Braking_distance).