The authors present preliminary results from a large-scale trial with Intelligent Speed Adaptation (ISA) in the Swedish city of Lund, where 300 vehicles are being equipped with ISA. The test area includes the entire city of Lund. However, the ISA system is only active within the 30, 50 and 70 speed limit zones. The system tested is the so called "active throttle, or accelerator". When the driver attempts to exceed the speed limit, the accelerator pedal exerts a counter-force. The performance of the vehicle is not affected at speed levels below the preset maximal speed. If necessary, the driver can override the system by pressing the accelerator pedal harder (kick-down function). Each vehicle is also equipped with a display indicating the actual speed limit, a digital map containing all the current speed limits within the test area and a GPS receiver which identifies the position of the vehicle. The test drivers are divided into groups due to gender, age and initial attitude towards the ISA (positive/negative). A selection of 80 drivers are observed using the "Wiener Fahrprobe" method twice, once before the installation and once one year after the installation. A selection of 20-25 drivers are studied to see whether there are differences in workload when driving with and without ISA. All test-drivers are interviewed four times; before their vehicle is equipped with the ISA, after driving with the ISA for one month, at half time and finally at the end of the project. Field studies are carried out in Lund as well as in the control city of Helsingborg. Speeds are measured on links, at junctions and pedestrian crossings, before and after the introduction of the ISA system. The ISA-equipped cars are marked in order to be able to compare them with non-equipped cars. The percentage of cars passing at amber or red at signalised intersections are observed. Interactions between car-pedestrian, car-bicycle and car-car are analysed at sites where the amount of ISA-equipped cars is expected to be high.
Abstract