Influence of Nonmotorized Vehicles on Speed Characteristics and Capacity of Mixed Motorized Traffic of Urban Arterial Midblock Sections

Abstract

Traffic stream characteristics are largely influenced by the presence of nonmotorized vehicles (NMVs) when mixed with the motorized vehicles in a non-lane-based heterogeneous traffic stream. The traffic stream operation becomes more chaotic with the high percentage of NMVs in a shared carriageway. Accordingly, in the present study, NMVs have been considered a friction factor influencing the traffic operations of motorized traffic. Speed-flow data has been collected through video graphic surveys at six urban arterial midblock sections. Among these sections, three have mixed motorized traffic; whereas, the remaining three sections have a significant proportion of NMVs mixed with motorized traffic. The data has been extracted from five-minute videos, which are further utilized to develop mathematical models relating the speed of each type of vehicle with the corresponding densities of all other vehicles present in the traffic mix. These models are solved for any predefined volume and proportions of traffic mix, and speed flow plots are developed to infer the capacity values. The capacity values are specifically compared with the capacity of a section restricted to motorized traffic, and it is found that the midblock capacity of urban arterials is reduced by 3.60%–35.82% when the percentage of NMVs are as low as 5% to as high as 25%, respectively. The study outcomes are useful for estimating the capacity of urban midblock sections in order to reduce the congestion due to NMVs on urban roadway networks.