Empirical analysis of impact of multi-class commercial vehicles on multi-lane highway traffic characteristics under mixed traffic conditions

Abstract

The presence and movement of multi-class commercial vehicles (CVs) under different traffic conditions in a shared roadway influences the highway traffic characteristics. The purpose of this study is to quantify the impact of the varying proportion of multi-class commercial vehicles (CVs) on the speed, dynamic passenger car unit (DPCU), capacity, and level of service (LoS) of the highways through empirical analysis. The speed-flow data were collected at highway sections in India, utilizing an Infra-Red (IR) sensor device. Individual vehicle speeds are predicted using the simultaneous equations approach, which are used to determine the respective DPCU factors of the vehicles and highway capacity at different proportions of multi-class CVs. The LoS threshold values are established based on the volume to capacity (v/C) ratio for the various percentages of multi-class CVs. The study results reveal that the multi-class CVs have had a unique effect on DPCU factors of the different vehicle categories under the influence of varying proportions of multi-class CVs. The highway speed reduced by 27.76% at 30% multi-class CVs compared to 5% multi-class CVs. Eventually, the highway capacity reduced by 24.25% at 30% multi-class CVs compared to 5% multi-class CVs. The LoS varied for each highway section accordingly from free-flow condition to the congested condition due to the incremental variation in the percentage of the multi-class CVs. The study indicates that the presence of a higher proportion of multi-class CVs significantly affects the speed, DPCU, capacity, and LoS of the highways.