Effects of an in-car speed limiter were investigated in three European countries, the Netherlands, Spain and Sweden, representing different regions and driving cultures. The study was carried out in urban and surrounding areas. Most of the European speed limit categories, ranging from 30 km/h to 120 km/h, were included. The effects of the limiter were greatest in free driving conditions outside platoons. However, the effects of the limiter were also seen in congested traffic, even though milder than in free driving. The effects were greatest in suppressing momentary high speeds, and consequently the variation of speeds was clearly reduced by the limiter. Some negative behavioural effects were also found. These were usually slightly higher numbers of short time-headways and the increased frustration and stress caused by the limiter. The acceptance of the limiter increased somewhat after trying it out. However, clearly less than half of the drivers would take the limiter voluntarily in their cars. The majority of the subjects accepted the speed limiter as a driver operated system. For the covering abstract see IRRD E102946.
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