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Vehicle Speed Calculator

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This calculator is used to determine the speed of a vehicle when the roadway friction, roadway slope and skid distance 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.

Roadway Friction:		Example: 0.60
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.
Distance of Skid Mark:	ft	Example: 100

This calculator utilizes the following equation:

V = √(30*D*F)

Where:

V = Speed of Vehicle (mph)

D = Distance of Skid Mark (feet)

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

This calculator does not account for speed loss due to an impact with another object, 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.