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)  
       
 

Where:

 

 

 

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.


Further Reading about Traffic Accident Reconstruction

Types of traffic accidents

Collision analysis in 10 steps

The accident scene investigation 

Atlanta Engineering Services, Inc. offers scene mapping... read more here

Learn how a vehicle black box and it's downloads can prove up evidence

View a sample engineering report here

Why you need an expert witness

Calculating the stopping distance

Multiple surfaces calculator to determine the stopping distance when there is more to consider.

Vehicle speed calculator

Accidents involving motorcycles

How a vehicle inspection analysis can help you after an accident

Reconstructing accidents involving Non-Commercial trucks

Read how vehicle defects can be the cause of a traffic accident here. 

It just may be those roadway ruts that caused you to hydroplane, find out more here

Was it poor design or layout that caused the accident?

See real 3D accident simulations with this link

More 3D accident reconstruction videos can be found here

See actual photos of traffic accidents here