Road accidentology: spotlight on precautionary measures

High speed, poor weather, driver fatigue, mechanical failure… An accidentologist loss adjuster’s role is to analyse each factor to determine the technical causes of a road traffic accident based on a man-machine-environment study.

Antoine Jarry, our accidentologist loss adjuster, describes his investigation method.


What is a man-machine-environment study?

A road traffic accident investigation includes several stages centred around the MME (man-machine-environment) system.

During these damage surveys, the accidentologist applies a detailed methodology to confirm and account for all existing parameters at the time of a collision. All of these observations make it possible to establish precautionary measures.


Analysing human behaviour

The driver’s physical and physiological condition is the first element to ascertain. At the moment of impact, the driver may be under the influence of alcohol, narcotics or medication.

For example, in a recent case a motorcyclist crashed into a car and toxicological analyses indicated an overdose of pain medication. What influence did that have on his driving?

Stress and fatigue can also cause accidents. So it’s important to gather the perceptions of various characters in order to obtain the most detailed picture possible of the human actions before, during and after the crash.


Accidentologist’s examination of the damaged vehicle

This examination is conducted in several stages ranging from the bodywork to the seat belts.

The loss adjuster begins with a complete circuit of the vehicle in order to evaluate its general condition before the crash. We make note of any traces of previous damage or changes after the accident, which often occur when the vehicle is removed and stored. Photos taken by the police when they arrive on the scene of the accident allow to make comparisons. This observation stage is followed by a classification of the crash using a code based on ISO and SAE* standards (*ISO 12353-1, SAE J224 standard). The CDC code (collision, deformation, classification) precisely specifies all the information on the vehicle crash using a series of letters and numbers (see document).

Deformations are measured in order to determine the forces involved in the collision.

Very useful information can also be found on the vehicle’s data recorders. The airbag diagnostic unit can indicate the speed of the impact when the crash occurred (frozen information) and examining the seatbelt allows me to determine if the person was belted in or not.

On-board electronics, particularly with the advent of self-driving cars, will provide additional information by delivering new driving parameters.

The vehicle examination ends with a check of the mechanical condition. We check tyres, ensure running gear is operational, verify lights and check the levels of the engine oil, coolant fluid and brake fluid.


Environment is a key factor when searching for causes

On the scene of the accident, the loss adjuster attempts to analyse the crash conditions. Was the road slippery? Was visibility reduced by a road sign?

The first step is to determine the road’s adhesion coefficient and gather geometric measurements (gradients, etc.). We can also identify braking or tyre scrubbing, and find debris from the cars spread around the area.

We pay careful attention to visual obstacles, so the loss adjuster will retrace the path of the vehicles involved several times using a dash cam in order to verify the visibility drivers had.

Poor weather conditions or a high contrast between light and shadow can also cause an accident. By visiting the place where the incident took place in conditions very similar to those of the accident (time of day, weather, etc.), it’s possible to discover a challenge or hidden object that impedes visibility and how they impact driving.

Once these elements (and many others) are gathered, the second part of the work begins, which consists of precisely recreating the accident using calculations and accidentology software.


Antoine JARRY, Transport & Lifting Loss Adjuster

Find out more about his area of expertise