Specifics of Bending Priority Road at Unsignalized Intersections

Unsignalized intersections with a bending priority road are common in Slovakia’s road network. Various specifics are associated with these type of intersections compared to conventional intersections with a straight priority road. There are different priority ranks for traffic streams, more complicated traffic situation, different traffic flow characteristics and driver behaviour. The problem is that only a few studies to date have addressed to this type of intersections and their specifics. Therefore, some traffic flow characteristics such as the speed of major-stream vehicles; and driver behaviour such as compliance with traffic rules, influences of potentially conflicting traffic streams on minor-stream drivers, and the driver gap-acceptance characteristics (critical gaps) at unsignalized four-leg intersection with a bending priority road in Zilina were surveyed. The results show vehicles moving along the bending major street about 40% slower than the city speed limit of 50 kilometres per hour. About 16% to 25% of drivers turning right from the major street did not signal the change of direction. About 16% of priority rule violations were recorded at the least priority minor approach during peak hours and long delays. There are two times more potentially conflicting traffic streams compared to intersection with the straight priority road and the effect of these potentially conflicting streams has ranged between 20% and 60%. The paper demonstrate that the values of critical gaps for the same movements more significant differ according to major/minor street and rank of priority, and critical gap values for straight traffic streams of third and fourth priority rank were determined to be about 0.4 to 0.9 second higher in comparison to the values for conventional rural unsignalized intersections. This new findings cause reduction of minor stream potential capacity and traffic safety.