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St. Louis Traffic Accident Reconstruction • PO Box 29537 St. Louis, MO 63126 All rights reserved © 2015 Home Articles

The Monte Carlo Method for Determining Auto Liability

Learn how the most current methods of mathematically analyzing auto collisions can allow you to compare a driver’s performance against the rest of the population.  Part 1 - Part 2

Eratosthenes and Auto Collisions: Science at Work

See how a scientific approach to collision analysis provides new insight on old ideas.

Most reconstructionists provide a range when calculating speeds.  This is because the uncertainty inherent in any investigation prevents that level of precision.  But what do you do if the range tells you that the driver was either speeding or 5 mph under the limit?  


You can solve this problem by running the calculations 15,000 times.  This allows you to test every reasonable input value.


Which of the following arguments is more compelling?  


It becomes obvious that a simple speed range would deprive a jury of information vital to reaching the right conclusion.



An ordinance violation occurs when you drive 5 mph above the posted limit.  Did this 5 mph make a difference?  Even if it did, you’re going to have a hard time convincing anyone using standard methods.  


With the Monte Carlo based collision models, we can make the most of the available evidence by calculating the probability of a collision at the speed limit as well as the probability of a collision at 5 mph above the posted limit.  If a vehicle traveling at the limit had a 49% chance of hitting the left turning car and a vehicle traveling at 5 mph over had a 51% chance of hitting the left turning car, then that 5 mph made the collision more likely than not.  


All of a sudden, that 5 mph went from being an insignificant admission, to a solid argument for negligence.


Download a sample report

Take a look at how much information you can get from a simple left turn collision with a minimal investigation.

Speed Ranges vs. Confidence Intervals

5 mph Can Make a Difference