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Vehicle Stopping Distance Calculator

This calculator is used to determine the stopping distance of a vehicle when the vehicle's initial speed, roadway friction and roadway slope are known.

The friction table below can be used to approximate the roadway friction based upon different roadway surface types and whether or not the surface is wet or dry.

  Vehicle Speed: mph Example: 45  
  Roadway Slope: % Use 0% slope for flat roadway. Use negative sign ( - ) for downhill grade. Example: 2.5 for uphill grade and -2.5 for downhill grade.  
  Roadway Friction: Example: 0.60  


  This calculator utilizes the following equation: D = V02 / (30*F)  





V0 = Initial Speed of Vehicle (mph)

F = Adjusted Friction = μ ± G where μ is the coefficient of friction and G is the grade of the roadway.

friction coefficients table

This calculator does not account for partial braking, variations in vehicle braking ability, hydroplaning conditions, tractor / trailers, and should not be used for vehicles traveling over multiple types of surfaces (ie. traveling over asphalt, concrete, gravel during one skid).

Atlanta Engineering Services, Inc. does not assume any liability for any errors in this calculator. This tool shall not be used for any insurance or litigation purposes. Atlanta Engineering Services, Inc. recommends that a licensed professional engineer specializing in traffic accident reconstruction be consulted for these types of situations.

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