The Road Administration wants to improve safety at a hazardous, rural road intersection near Aakersberga, Stockholm by changing the design of the intersection. The intersection today is a three-way connection with a small road connecting to a four-lane main road, much similar to a motorway with high speeds although with a speed limit of 90 km/h. Drivers' attention and velocity in different designs of the intersection are analysed in this thesis with data from two experiments, ordered by the Road Administration and conducted by the Swedish National Road and Transport Research Institute (VTI). Four alternative designs of the intersection were tested using the VTI-simulator; a narrowing from two to one lane through the intersection, rumble strips, a wooden fence and trees at the road side, and a portal framing the intersection. In addition, the original intersection design, both with and without speed limit signs of 70km/h, were tested for comparisons. In the first of the two experiments, the four alternative intersection designs all had speed limit signs of 70 km/h, and in the second experiment the alternative intersection designs were tested without the influence of the speed limit signs of 70 km/h. Data used in the analyses are velocity data, lateral position, eye movements, brake data and subjective estimations. Subjects were found to look at the critical areas of the intersection in time, independent of intersection design. Only small differences between the intersection designs were found, probably due to width of the main road being a larger design-influence than the measures tested. The results are in favour of the narrowing from two to one lane through the intersection, but traffic density and rhythm make a narrowing difficult to realise at the real intersection. Instead, rumble strips in addition to a speed limit of 70km/h can be recommended, although rumble strips are most likely to increase inattentive drivers' readiness. (Author/publisher) This report is also available via Internet at http://liu.diva-portal.org/smash/record.jsf?pid=diva2:17323
Abstract