Average speed on Norwegian roads with an 80 km/h speed limit has decreased by about 1 km/h during the last 5 years. This is partly due to an increase in the share of older drivers, and the fact that older drivers drive more slowly than younger drivers. This was shown in a three-phase project: A) Analysis of speed data from permanent traffic counting stations; B) Speed measurements combined with downstream driver interviews and with register data on vehicles and owners; and C) Estimation of changes in kilometres driven by older drivers, based on national travel surveys in 2008 and 2014. Even though the changed age composition of the driver population explains part of the speed decrease, most of the decrease is due to other factors, and probable explanations are increased traffic volume and decreased prevalence of large speeding violations. (Author/publisher)
Abstract