The effects on speeds and speed distribution were studied in a large scale field trial with an in-car system for speed adaptation in the city of Lund, Sweden, In the trial 290 vehicles were equipped with an "active accelerator pedal" and a data logger for a period of 3-11 months. Data were logged in each test vehicle during the whole trial and were analyzed for 3 one-month periods: before activating the system, after short time use and after long time use. The results showed significant reductions in the speed level. Speeds on stretches decreased statistically significantly (p less than 0.05) at 60 out of 69 observed sections. The effects were largest on arterial roads, at mid-block sections, where the prevailing traffic conditions and street design allows higher speeds. The standard deviation decreased on all arterial roads, mainly due to the decrease in speed of the fastest vehicles but there was also an effect from an increase in speed of the slowest vehicles. On streets with mixed traffic no differences in speed or speed distribution could be shown. This is most likely due to the fact that speeds were already controlled by the prevailing traffic conditions and they already were so low that the system never had to interfere. Further research is needed in order to investigate possible behavioral adaptation effects when the system is active as well as inactive and how driver behavior would be influenced in a situation where a large part of the vehicle fleet is equipped with an active accelerator pedal. (Author/publisher).
Abstract