The number of road accidents appears to be one of the few traffic statistics w h i c h has been steadily i m p r o v i n g over time (Box 7.1). Moreover, it is a measure i n which the United K i n g d o m compares favourably w i t h other countries (Box 7.2). But such measures provide an incomplete picture in that they do not record the changes i n the behaviour of unprotected road users as they try to adapt themselves to the growing volume of traffic. These adaptations can be readily observed and they are not without cost. Furthermore, w i t h the notable exception of air transport (which accounts for only a very small fraction of travel w i t h i n the U n i t e d K i n g d o m ) those modes of travel w i t h the worst safety record are growing fastest.