Typical human errors in traffic accidents involving powered two-wheelers

Powered two-wheelers (PTWs) are among the users who are most vulnerable to road risks. In 2009, motorbike traffic accounted for 1.2% of all motor vehicle traffic in France, whereas they constituted 14% of the vehicles involved in bodily injury accidents and motorcyclists accounted for 23.5% of motor vehicle fatalities (ONISR, 2009). In part, this vulnerability comes from the high level of PTW user fragility due to the absence of protection from the vehicle body, as the slightest collision exposes the user to injury. But it also entails greater involvement in certain accident categories. These two characteristics of their accidentalness are testimony to the problem of the mismatch between PTWs and the traffic system. PTWs stand out in traffic by their specific behaviours (position on the carriageway, levels of acceleration, types of overtaking, etc.), their particular dimensions, their low representation in traffic and a wide range of uses, practices and behaviours that depend on the PTW categories (50cc, 125cc or high-powered motorcycles). For an analysis of this complexity, we have to move beyond a simple quantitative description of the phenomena to achieve an analysis with an understanding of the difficulties that powered two-wheelers encounter during their interactions with other road users. This approach also enables us to gain a more in-depth understanding of the difficulties that other road users encounter with PTWs. Accidents shed light on the difficulties that drivers are unable to overcome in the driving situations they are confronted with. The detailed analysis of driver failures, of the contributing factors and of the accident circumstances where these arise, provide us with precious information on the difficulties facing PTWs and those confronted with them. The first section of this chapter is specifically dedicated to the results of an accident analysis of the different types of operational problems in the interactions between PTWs and other users. This first section shows an over-representation of accidents involving a problem of PTW detection. The second section focuses on the problem of PTW conspicuity that is commonly observed in these accidents.