A Quick Method for Estimation of Level of Service at Manually Operated Tollbooths under Mixed Traffic Conditions

摘要

The present study attempted to develop a methodology to quickly estimate the level of service (LOS) at manually operated tollbooths where approaching traffic volume is mixed in nature in the same lane. Videography data collected at five toll plazas located in northern and western part of country. The vehicle approaching at toll plaza were divided into seven categories and headway data extracted from the video. The time headway is measured by taking the time difference of two consecutive vehicles at the same tollbooth. Field observation shows that there is a wide variation observed in headway for different vehicle type as well as within same vehicle type as leader and follower vehicle combinations. This may be due to varying toll rate, vehicle characteristics, drivers and tollbooth operators’ personal attributes. The present study developed tollbooth capacity estimation model by taking harmonic mean of traffic composition present at tollbooth with respect to the capacity achieved of respective vehicle class using headway method. Using approach volume and capacity estimated with the help of developed model in the volume to capacity (V/C) ratio is calculated and LOS thresholds are defined using clustering technique. The field observed V/C ratio ranges from 0.28 to 1.30. The study proposes six LOS ranges from LOS ‘A’ to ‘F’ at toll plaza based on V/C ratio. A threshold V/C ratio of less than 0.50 has been defined for LOS ‘A’ whereas more than 1.05 represents LOS ‘F’. The study outcome will be useful for toll plaza management and field engineers to quickly evaluate LOS at toll plaza with less efforts and cost.