EVALUATING VEHICLE RESUSPENSION EMISSIONS BASED ON ROADWAY AND VEHICLE CHARACTERISTICS

Abstract

Vehicle related particulate matter (PM) emissions remain a significant air quality concern despite substantial reductions in tailpipe emissions over recent decades. As exhaust controls have improved and vehicle electrification has increased, non-exhaust emissions, including road dust resuspension, have become a growing contributor to traffic-related particulate matter. However, the mechanisms governing vehicle induced resuspension are not fully understood, particularly at the individual vehicle level. Existing regulatory and modeling approaches largely rely on fleet-averaged assumptions and often emphasize vehicle weight without fully accounting for aerodynamic effects, operating conditions, or measurement methodology. This research investigates vehicle induced particulate resuspension through a controlled experimental framework designed to isolate vehicle level and operational influences. Three primary research questions guided this study. First, how does sensor location influence the measured spatial distribution of particulate matter concentrations around a moving vehicle? Second, how does vehicle weight, speed, and road surface type affect resuspension emissions? And third, beyond vehicle weight, how do aerodynamic differences between vehicles influence particle resuspension generated by vehicles? To address these questions, a factorial experimental design was implemented using five vehicles representing internal combustion, hybrid, and battery electric platforms. Testing was conducted on both gravel and asphalt road segments at controlled speeds of 30 mph and 50 mph. Each vehicle was evaluated under base and increased weight conditions (+624 lb.). Four sensor locations were employed on each vehicle, front bumper, rear bumper, front tire, and rear tire, to evaluate spatial variability in particulate concentrations. Steady-state driving segments were isolated and subdivided into repeated 30-second trials for statistical consistency (N=10 per experimental condition). Analysis of variance (ANOVA) was applied to evaluate main effects and interactions across experimental factors. Results demonstrate that sensor location significantly influences measured particulate concentrations. Rear-mounted sensors consistently recorded higher PM2.5 concentrations than front-mounted sensors, reflecting the concentration of resuspended particles within the vehicle wake rather than uniform distribution around the vehicle body. This finding highlights the importance of sensor placement in experimental design and exposure assessment, as measurements are highly dependent on sampling location. Vehicle speed and road surface type were identified as dominant factors influencing resuspension emissions. Gravel surface produced substantially higher particulate concentrations than asphalt, and higher vehicle speeds amplified resuspension across both surfaces. The addition of vehicle weight produced measurable but comparatively smaller effects within the tested conditions. Importantly, statistically significant differences (p < 0.05) were observed between vehicles under identical speed and road conditions, suggesting that aerodynamic and geometric characteristics beyond mass contribute to resuspension behavior. Overall, this research demonstrates that vehicle-induced resuspension is governed by combination of operational, environmental, and vehicle-specific factors. The findings challenge simplified assumptions that mass alone dictates non-exhaust emissions and highlight the importance of controlled experimental methodologies for isolating vehicle level effects. From a systems engineering perspective, this work integrates sensing, experimental design, data processing, and statistical modeling to better characterize a complex transportation environment interaction. The results provide insight for future regulatory frameworks, vehicle design considerations, and measurement strategies aimed at reducing non-exhaust particulate emissions in an increasingly electrified transportation system.