Within the framework of the Swedish national trial with Intelligent Speed Adaptation (ISA) in urban areas, 284 cars have been equipped with an active gas pedal for a period of up to 11 months in the city of Lund. When evaluating the effects of the system, there is a special interest in the behavioural adaptation effects the system might bring. Alongside data-logging and interaction studies, in-car observations were used to study this. Twenty-eight drivers have been studied by two observers in an instrumented vehicle during a 45 minute drive (33 km). The observations were carried out twice, before driving with active gas-pedal and after driving with it for 5-11 months. One of the observers carried out coding observations, which means he studied standardised behaviour such as yielding behaviour and speed adaptation. The other carried out free observations which means that he studied communication, interaction and events that occurred irregularly e.g. conflicts. One of the variables that were studied in this experiment was behaviour towards pedestrians/cyclists at crossings. The observers also registered yielding behaviour. Speed was of course of interest in this study and it was registered both by a data-logger and the observers. The use of an instrumented vehicle made it possible to study car-following distances with a laser-radar that measured the distance to the vehicle in front. No difference could be found in drivers' speed adaptation in low speed situations when they were driving with ISA. Behaviour towards other road users improved as well as car following and yielding behaviour improved so it was not possible to trace any sign of negative compensatory behaviour. Some indication on the occurrence of the phenomenon "delegation of responsibility" to the system could be traced: in some cases the drivers forgot about the speed-limit outside the test area. For the covering abstract see ITRD E123876.
Abstract