Abstract

Objectives : The study aims at identifying the various factors that trigger or deteriorate the consequences of fatal crashes involving motorcycles in 2015.

Method  : It is based on the use of the FLAM accident report database, which includes 87% of fatal accidents involving at least one motorcycle in 2015.

Results  : Factor analyses are derived from the aggregation of factors determined to be almost certain and probable. For the 558 fatal motorcycle crashes in the FLAM database, nearly 1830 factors are identified as triggers, of which more than 1300 are qualified as near-certain (72%).

A greater multiplicity of factor types than in fatal accidents without PTW

The combinatorial analysis of the data according to the components human, vehicle, infrastructure, weather conditions shows that the share of accidents involving at least one human factor is 94%. Accidents involving a motorcycle stand out from those not involving a motorcycle, we note:

• Vehicle factors 2,3 times more present,
• Infrastructure factors 1.3 times more present,
• a greater multiplicity of factors (33% of accidents involve only human factors, compared to 50% of accidents without motorcycles).

Motorcycles had a high stake in fatal overtaking accidents in 2015: 25.6%. All types of motorcycles are involved: roadsters, sport bikes as well as scooters or customs.

The risk exists during the maneuver but also immediately afterwards:

• 19% of motorcyclists are injured while overtaking,
• 7% have just finished overtaking.

In 2015, 20% of heavy motorcycle drivers involved in fatal accidents were riding in groups (bunches of several riders). Groups of 2 were the majority (44%).

These motorcyclists were mainly involved in accidents outside built-up areas (82%), on two-bidirectional roads (85%). 63% were riding on curves.

There was a high proportion of triggering and aggravating infrastructure factors:

• 45% of the accidents were related to infrastructure,
• 40% of the accidents were aggravated by the presence of a fixed obstacle on the shoulder.

We also note some specificities in the human factors:

• a significant failure to respect safety distances (11%),
• a problem linked to lack of experience: 21% of factors linked to the poor riding experience or the youth of the driver and 14% of factors linked to the unfamiliarity of the motorcycle,
• less alcohol and drugs for motorcyclists riding in groups than for those riding alone (respectively 14% vs. 24% for alcohol impairment; 7% vs. 18% for drug impairment).

Conclusion  : This study confirms the prevalence of human factors as causal factors in motorcycle accidents. The results confirm the important stakes linked to certain factors, more particularly excessive or inappropriate speed, driving a powerful motorcycle or the low perceptibility of motorcycles. Various specific themes were highlighted, such as the issue of overtaking manoeuvers or riding in bunches.