Light PTWs became increasingly popular in the period from 1998 until 2005, especially amongst younger people in Norway. Both the number of mopeds, encompassing PTWs with cylinder volume less than 50 cm3 and maximum speed within 45 km/h, and light motorcycles, encompassing PTWs with cylinder volume within 125 cm 3 and motor effect within 11 kW, have increased significantly. From the year 2000 the number of registered mopeds in Norway has increased from 118.000 to approx. 140.000 in 2003. And, since 1997 the number of light motorcycles has tripled (from approx. 4.000 in 1996 to approx. 11.500 in 2003). This increment is probably due to the changes in taxes, making this category vehicle more favourable (Bjørnskau 2004).