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Vehicle Speed Calculator over Multiple Surfaces and then Impacts

A Calculator for multiply surfaces are useful to calculate speeds of vehicles traveling over one or more surface types.

This calculator can be used if there aren't multiple roadway surface types or an impact. In this situation, just leave the extra input fields empty.

	Surface 1	Surface 2	Surface 3	Impact
Roadway Friction:
Roadway Slope:	%	%	%
Distance of Skid Mark:	ft	ft	ft
Speed Loss Due to Impact:				mph

When inputting roadway slope data above: Use 0% slope for flat roadway. Use negative sign ( - ) for downhill grade. Example: 2.5 for uphill grade and -2.5 for downhill grade.

Calculator uses the combined speed formula:

S_c = √(S₁² + S₂² + S₃² + S_Impact²)

Where:

S₁ = Speed Loss Accross Surface 1 (mph) = √30*D₁*F₁

S₂ = Speed Loss Accross Surface 2 (mph) = √30*D₂*F₂

S₃ = Speed Loss Accross Surface 3 (mph) = √30*D₃*F₃

S_Impact = Speed Loss Due to Impact (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.

The friction table below can approximate the roadway friction based upon different roadway surface types and whether the surface is wet or dry.

This calculator does not account for hydroplaning conditions and tractor / trailers.

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.