The object of the study was to assess the effects of sound and vibration feedback producing profiled edge lines on driving behaviour. In addition to that, road users' experiences and opinions concerning profiled road markings were questioned. The investigation was carried out by resorting to various methods. These were driving an unobtrusive instrumented car on the route having different types of profiled road markings including control sections without profiled edge lines, interviewing subjects after the test drives, measuring the speeds of the traffic flow in the experimental area in the day light, at dusk and at night, and a road side survey targeted to drivers travelling in the area to find out their opinions and experiences in terms of feedback producing edge lines. Speed measurements carried out by the instrumented car showed that on the road sections having profiled markings mean travel speeds generally increased. The increase in the mean travel speeds was mainly from 1 km/t to 3 km/h. The speeds increases both in day time and at night. This was probably caused by the high retroreflectivity of new road markings and the following extended visibility distances. It is noteworthy that the standard deviation of speed mainly decreased. The increase of speed level was greatest in good driving conditions on a high standard dual carriageway road. In terms of using road markings, currently more consideration ought to be devoted to optimal visibility of road markings instead of maximum visibility, when defining retroreflectivity levels also the expected effects on speed level needs to be taken into account. The precise lateral position of the instrumented car in respect with the edge line was also defined. There were not great changes in the lateral position of the car without regarding in left bends, where the subjects were travelling slightly closer to the centreline on road stretches with profiled road markings. The profiled 20 cm wide edge lines shifted the position of the test car about the magnitude corresponding the width of the line towards the centre of the road. When judging the changes in the lateral position of the test car, it may be concluded that introducing profiled edge lines had no negative effects on the lateral control of the car. A slight shift of the car towards the centre of the road has rather positive than negative safety effects, since according to in-depth investigations of accidents, driving too close to the road edge is a considerable greater safety problem than driving too close to the centre line. The interviews of test drivers and the roadside survey showed that drivers find profiled road markings very useful. Almost 30% of the respondents in the roadside survey told that profiled road markings had sometimes alerted them to keep the car on the lane. Some 16% of the same respondent group reported to have changed their driving manner due to profiled road markings. The magnitude of the vibration effect of markings were approved of by 87% of the respondents. More than 90% of the interviewees thought that profiled road markings would increase traffic safety. Two thirds of the respondents wanted that profiled road markings would be used only as edge lines, whereas only one third would like to see them used both as edge and centre lines. It is noteworthy that 90% of the interviewees regarded edge and centre lines important in adverse visibility conditions. Also the subjects' interviews suggest that driving is easier in adverse visibility conditions on roads with profiled road markings. Elderly drivers found good road markings important in all driving conditions. (A)
Samenvatting