Bridgestone Safety Challenge - Disclaimer
The actual total stopping distance may differ from the baseline value when the road or tyre conditions are substantially different from the baseline conditions or when the driver's cognitive function is superior or deficient.
The result is a rough approximation for your information based on a theoretical model where the only input parameters are general weather conditions, speed and type of tyre. The formula used is d=v²/(2*u*g) where:
- d = breaking distance
- v = velocity
- u = friction (based on which type of tyre and general weather conditions)
- g = acceleration due to gravity on earth (9,8m/s²)
To determine actual stopping distance, one would typically empirically obtain the coefficient of friction between the tyre material and the exact road spot under the same road conditions. Road conditions depend on a number of factors such as temperature, slope, wear rate and depth of snow or ice on the roadway. They would also measure the size and weight of the car, and the person's perception and reaction times.
- Taoka, George T. (March 1989). "Brake Reaction Times of Unalerted Drivers" (http://www.ite.org/membersonly/itejournal/pdf/jca89a19.pdf)
- Wikipedia (http://en.wikipedia.org/wiki/Braking_distance)
- An investigation of the utility and accuracy of the table of speed and stopping distances (http://www.virginiadot.org/vtrc/main/online_reports/pdf/01-r13.pdf)
- Frictional Coefficients for some Common Materials and Materials Combinations and Reference Tables (http://www.engineershandbook.com/Tables/frictioncoefficients.htm, http://hpwizard.com/tire-friction-coefficient.html)
- Code of Virginia 46.2-880 Tables of speed and stopping distances (http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+46.2-880)
- 6. Cornell local roads programm - Winter Driving: How to stay safe and still get there (http://www.clrp.cornell.edu/tip_sheets/pdf/driving.pdf)