QUANTIFICATION OF LEVEL OF SERVICE OF U-TURNS IN MEDIAN OPENINGS UNDER MIXED TRAFFIC CONDITION

Abstract

Median openings are provided to facilitate the U-turn movement of vehicles. Majority of median openings are uncontrolled and no priority is given for through vehicles. Uncontrolled median openings result in two kinds of delay. Firstly, the U-turning vehicles impart delay to the through traffic. At the same time, U-turning vehicles are also subjected to a certain amount of delay while waiting for suitable gap to merge with the through traffic stream. The delay experienced by U-turning vehicles are referred to as service delay while the delay experienced by the approaching through vehicle at the median opening is termed as median delay. The effect of both U-turning and through vehicles are incorporated into a single term referred to as area occupancy. The Level of service (LOS) of U-turn movement at a median opening will be beneficial to analyse the operational efficiency of the traffic facility. Service delay, median delay and area occupancy are used to quantify the LOS of the U-turn facility. K- Means clustering method is adopted in this study to group the parameters to define the LOS. A comparison among the different LOS classification using the various parameters are also conducted. The delay was found to have an exponential increase with rise in vehicular volume with the two-wheelers experiencing the lowest delay. The models developed from this study can be used to determine the delay parameters from the vehicular volume obtained from field data. Clusters were developed for all three parameters that were classified from A to F. The operational efficiency of various traffic facilities can be analysed by the LOS determination. A better understanding of such facilities can help to avoid the problems of congestion and thereby improve the overall quality of service in such facilities