Comprehensive Review Of Pedestrian And Nmt Roadside Friction Impacts On Heterogeneous Urban Traffic Systems

Abstract

Urban traffic in developing countries is complex due to heterogeneous traffic, with mixed motorized and non-motorized vehicles (NMVs), poor lane discipline, and roadside friction from pedestrians, bus stops, on-street parking, and commercial encroachments. This review synthesizes 50 studies to quantify impacts on traffic speed and capacity in mixed traffic settings. Pedestrian movements reduce speeds by 0.35 km/h to 67% and capacities by 0–63% (200–5,700 PCU/hr, higher reductions at unspecified volumes), with minimal impact below 220 Peds/hr but significant losses at 1,360 (up to 50%) and 1,550 Peds/hr (up to 40.73%). NMVs and parking reduce speeds by up to 36% and capacities by up to 57%, with lane width reductions causing similar drops. Conventional homogeneous traffic models fail to capture these dynamics, as shown by field observations, VISSIM simulations, headway analysis, and midblock capacity studies. A novel Roadside Friction Index (RSFI) integrates these friction elements, offering urban planners a standardized tool for strategies like bus bays and dynamic parking systems. This enhances urban mobility, aligning with SDG 11 (sustainable cities). Future research should refine the RSFI with real-time data and develop adaptive traffic control to optimize flow in heterogeneous conditions.