CRITICAL INTERVALS AND QUEUE INTERVALS AT TWO-LANE ROUNDABOUTS

Over the past decade, a number of manuals have been developed for rural road roundabouts in the Russian Federation. However, two- and three-lane roundabouts are designed and operated in cities of the Russian Federation do not yet have manuals that take into account the specific features of this urban intersections. The development of such do not yet have manuals involves defining all multi-lane roundabout characteristics which used in consistent calculations of capacity, traffic delays and queue length. The objective of the study is to develop a methodology of multi-lane roundabout capacity estimation. At this stage, a study was done to determine the values of critical headway and follow-up time for two-lane roundabouts. Research methodology. Video rings were received from the city of Bratsk, Petrozavodsk, Pskov. The headways measured between the front bumpers of cars, were recorded on each lane of the circular roadway. Accepted and rejected headways were highlighted, as well as the number of vehicles using each accepted headway. Critical headway and follow-up time were determined using linear regression models. Study Result. It was found that the values of critical headway and follow-up time of the left and right entry lanes have different values. These results proved the validity of capacity calculation methods based on a separate consideration of each of entry lane. Objectives for further research. Further research will focus on estimation of critical headway and follow-up time for three-lane roundabouts. It is also necessary to establish the influence of traffic volumes on the headway distribution on two- and three-lane circular carriage way. Consistent solving of mentioned above research tasks will allow to form an estimation methodology for all characteristics of multilane roundabouts. Key words: two-lane roundabouts, conflict points, critical headway, follow-up time, regression analysis.