The objective was to answer the following questions: (1) how do the drivers experience the different types of Intelligent Speed Adaptation (ISA): informative, compulsory and recording?; (2) how does the ISA affect driving behaviour?; and (3) what are the differences between the different types of ISA systems? In a field study 24 subjects drove the instrumented car with route guidance and ISA. Every subject drove the same route four times. The route included different types of traffic environment with different speed limits. The speed limits were 40, 60, 70 and 80 kilometres per hour and the environment varied from motorway to residential area. The driving time differences from the base level to the different ISA systems were not significant. However, ISA systems seemed to be effective in reducing speeding, especially excessive speeding. The most effective speed reducer seemed to be the compulsory system. The informing system was also effective and some reduction was also seen with the recording system. The problem is that the acceptability of ISA systems was just the opposite. The compulsory system was rejected, and the informing system was not found very enjoyable. Nevertheless, the drivers approved of this one more, because they felt that they still had control of their car, even though the voice signal was considered to be annoying. In the WORKLOAD interviews and in the free comments the drivers were very pleased with the extra information. The recording system was the most popular. One interesting point is how effective the recording system would be in the future, in everyday use. The recording system was tested without any mentioned consequences ¡ the speed offence result was only indicated to the driver himself and the experimenter. (A) For the covering abstract of the conference see ITRD no 207828. The reprints are also available at the web - http://www.vti.se/pdf/reports/K18APart1.pdf ; http://www.vti.se/pdf/reports/K18APart2.pdf and http://www.vti.se/pdf/reports/K18APart3.pdf.
Samenvatting