In 1997 the general speed limit was increased with 10 kph, without any preparation, during the summer period for almost all roads with a speed limit of 90-kph. Since the decision came as a surprise a study of the effects were based mainly on accident statistics and a relatively small amount of speed measurements. The outcome of the study was that the increase had a mainly negative effect of the general traffic safety situation. The beginning of 1998 saw a new decision of increased speed limits but this time only on certain sections of Estonian main roads with a 90-kph speed limit. The increase was 10, 20 or 30 kph. This time, however, a better prepared analysis of this seasonal variation in the speed limit could be done. The paper provides the background followed by an overview of international research on the relationship of speed and safety. The focus is on the results from the studies of the variation in speed limits, during the summer of 1998. Speeds were measured on roads with an increase of 10 or 20 kph, together with control roads, before, during and after. Impacts on accidents rates were analysed. Roadside interviews with 1600 drivers about their opinion of the experiment were also carried out.
Abstract