One underlying dilemma has not been adequately resolved. On the one hand, in terms of accident or fatality risk, the transport system becomes safer as the years go by. In almost all countries for which reliable statistics are available, risks have been decreasing over time. At the same time, exposure, measured in vehicle kilometres travelled has continued to
increase in most countries. The result is that in many cases the absolute number of accidents, and in some cases the number of fatalities have continued to increase. As to effectiveness it could be said that the transport system has become more efficient in terms of the number of accidents or fatalities it produces for each unit of exposure, however, in overall terms of safety, the system has become less safe by producing more casualties, or fatalities in some countries, as a result of the increased exposure. To produce further safety improvements it should therefore be attempted to reduce levels of exposure by modes of transport that have high risks associated with them and convert some of that exposure to modes that have lower risks. Even that approach should be regarded with caution as the following two examples will demonstrate.