Description

This study presents the empirical development of congestion cost equations specifically calibrated for multilane highways operating under mixed traffic conditions in India. Mixed traffic environments, characterized by wide variations in vehicle speeds, sizes, and maneuverability (ranging from motorized two-wheelers and three-wheelers to heavy commercial vehicles), present unique modeling challenges compared to homogeneous traffic streams. The research utilizes extensive field data collected across primary arterial corridors, measuring volume-capacity ratios, free-flow speeds, travel time delays, and fuel consumption rates under varying traffic densities. By converting heterogeneous traffic streams into standard Passenger Car Units (PCUs) and analyzing speed-flow relationships, the authors derive explicit mathematical equations estimating additional economic costs incurred due to traffic congestion. These costs account for increased vehicle operating costs (VOC), extra fuel consumption, accelerated vehicle wear and tear, elevated tailpipe emissions, and travel time losses for passenger and freight transportation. The developed equations demonstrate how congestion costs escalate non-linearly as traffic demand approaches and exceeds highway capacity. The paper integrates these equations into economic appraisal frameworks, enabling transport planners to evaluate the feasibility of highway capacity expansion, lane additions, and access management projects. The findings provide transportation agencies in developing nations with essential parameters to quantify the economic drag of traffic congestion and prioritize infrastructure investments.