Powered two-wheelers within the traffic system. Editorial

The world of powered two-wheelers has changed dramatically in recent decades, along with a steady increase in the number and diversity of the fleet and uses. This evolution has led to some benefits in terms of mobility, but also some drawbacks in terms of safety. The problems involved are neither simple nor monolithic and there is a lack of knowledge about their different facets and backgrounds that require research work both in terms of risk exposure, accidents factors and impact severity. This special issue of Accident Analysis and Prevention regroups 30 papers devoted to an improvement in this knowledge, exploring the different aspects involved in the safety of powered two-wheelers by complementary methods. 1Powered two-wheelers in a complex, moving world Nothing is simple in the traffic world and everything in it is in constant motion. Powered two-wheelers (PTWs), including motorcycles and mopeds – whether classical or scooter models – are a good example of these complexity and evolutionary aspects, considering their recent development and the specificity of the interactions that they give rise to in traffic, sometimes revealing weaknesses in the transport system design, lacks in its protections and holes in its defenses. PTWs constitute an individual transport mode providing travel freedom and flexibility, making it possible to travel relatively quickly due to their capacity to overtake vehicles, allowing riders to get through most traffic jams, and making it easier to find a parking place very close to the destination. There has been major growth in motorcycling the last decades in most parts of the world in relation to economic and social changes. In many developing countries, specifically in Asia, the increase in urbanization and motorization has led to an increase in PTWs in conjunction with new needs in mobility and because of their easier accessibility, lower cost of use and smaller dimensions as compared to cars (Haworth, 2012). In high income countries, the evolution of the economic and social context, including elements such as the cost of fuel, the development of traffic congestion, car traffic management policies in cities, changes in lifestyle, etc., has also led to an increase in the use of PTWs both for commuting and for touring (Shinar, 2012). The fleet of motorcycles is estimated at 313 million worldwide, most of them in Asia (77%), with Europe and North America comprising only 16% of the global fleet (Rogers, 2008). One consequence of this growth is an increase in exposure to traffic risks. There has also been a large increase in the diversity of PTWs. Today there is a wide variety of models that cover a wide range of technical capabilities (engine capacity, power to weight ratio, size, maneuverability, etc.) corresponding to a wide variety of users and uses to which they are dedicated. Accident Analysis and Prevention 49 (2012) 1-4 / DOI: 10.1016/j.aap.2012.09.007 2 For example, a recent trend consists of an increase in use of motorcycles and scooters by women (Rogers, 2008), which leads to the adaptation of vehicles and the equipment industry toward this population. PTWs have therefore led to a twofold change in terms of the expansion and diversification that the transport system must harmoniously integrate. Despite the potential benefits connected to their use, PTWs suffer from some drawbacks. With only two wheels in a line, they are more difficult to control and riders are more sensitive to external disturbances (road difficulties, weather), so something that is not a problem for car drivers can become a major difficulty for them. For example, poor road surface conditions or small objects on the road (e.g. gravel) are likely to cause loss of control of a PTW. More generally, because of the technical specificity related to their small size, their high maneuverability, their acceleration capabilities and the use made of them (e.g. filtering), these vehicles generate interactions that were not originally foreseen in road design. The public transport space was primarily designed from the perspective of automobile traffic. Concerns and interventions have historically focused on the safety of four-wheel vehicles (Muzira, Chesheva, Banjo, and Marquez, 2009). It gave sidewalks to pedestrians, bike lanes to cyclists, bus lanes to buses, but no specific path was reserved for PTWs, which must fit into streets that are crowded with cars, notably in Western countries where, some decades ago, PTWs had very little incidence on traffic. It should be realized, however, that these two modes of travel entail different underlying practices and their interactions are sometimes confrontational, almost systematically to the disadvantage of riders, who are very vulnerable in case of the slightest collisions and falls.