Critical headway and follow-up time analysis at two-lane roundabouts

Abstract

Design of urban intersections, as well as the traffic control design on them requires the development of methods of capacity, traffic delays and queues estimation. Two and three-lane roundabouts are designed and operated in many cities of the Russian Federation. Currently there are no approved methods of performance estimation of such multilane roundabouts. The development of such methods would require the determination of all characteristics which are used in consistent calculations of capacity, traffic delays and queue lengths. Research target is to establish the values of multilane roundabouts critical headway and follow-up time. Two-lane traffic circles are analyzed at this research stage. Video records were received from the cities of Bratsk, Petrozavodsk, Pskov. The headways measured between the front bumpers of cars, were recorded on each lane of the circular roadway. Critical headway and follow-up time were determined using linear regression. 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. Further research will focus on estimation of critical headway and follow-up time for three-lane roundabouts. Consistent solving of mentioned above research tasks will allow to form an estimation methodology for all characteristics of multilane roundabouts.