Research On The Fugitive Road Dust Emissions Estimation And The Effectiveness Of Control Measures Based On TRAKER Method

In recent years,local governments have invested a lot of human,material and financial resources in the control of fugitive road dust（FRD）.Therefore,it is of great practical importance to use a fast,convenient and low-cost method to estimate FRD emissions and to evaluate the effectiveness of control measures to improve the quality of urban air environment.This paper analyses the spatial and temporal distribution characteristics of FRD emissions through TRAKER（Testing Re-entrained Aerosol Kinetic Emissions from Roads）method walking detection in Weifang and Baoding,establishes the relationship model between road dirtiness index（a）obtained by TRAKER method and silt loading（s L）obtained by AP-42 method,evaluates the effectiveness of three FRD control measures in terms of the removal efficiency of PM deposited on the road（η_a）and the PM concentration reduction efficiency in the road environment(η_PM)for short periods of time for water-sprinkling,vacuum sweeping and sprinkling-vacuum sweeping,analyses the influencing factors and proposes optimal FRD control solutions.The results of the study showed that:in the road cleaning mode with independent water-sprinkling or vacuum sweeping operation,the a and the PM concentration in the road environment（T_T^*）were consistent with the daily variation during the peak traffic period;in the uninterrupted sprinkling-vacuum sweeping operation mode,a was higher before 14:00 and lower afterwards,and T_T^*was relatively delayed by 1 hour.a and T_T^*were lower in the city in administrative,cultural and educational,commercial,residential and industrial areas,and higher around construction sites.a and T_T^*varied in opposite directions in urban-rural,rural and coastal areas.Extending the application of the TRAKER method,it was found that s L had a good positive correlation with PM₁₀road dirtiness index(a₁₀),and linear regression is the best-fit model,which can be used to calculate road s L distribution characteristics and evaluate road pollution levels.To evaluate the effectiveness of FRD control measures,it was found that:the initialη_a andη_PM for water-sprinkling were 74%～100%and 5%～77%respectively,with a parabolic trend of a short rise in the middle and then a continuous decline,and theη_aandη_PM at 1 hour were 4%～100%and 25%～68%respectively.The predicted average duration ofη_a>0 andη_PM>0 were 62 min and 72 min respectively.The initialη_a andη_PM of the vacuum sweeping were the lowest,ranging from 2%to 26%and 14%to34%,respectively,followed by a brief decline or even a negative effect,and then a continuous increase with a parabolic trend,withη_a andη_PM reaching 39%to 72%and 40%to 65%at 1 hour,respectively.The predicted average time required ofη_a andη_PM to reach 100%was 80 min and 75 min,respectively.The initialη_a andη_PM of the sprinkling-vacuum sweeping were the highest,reaching 90%～98%and 73%～94%,respectively,and then declined linearly or tended to be horizontal.Until 1 hour,η_a andη_PM were 69%～92%and 66%～88%,respectively.The predictedη_a andη_PM effect duration is above 3 hours,and the efficiencies are the highest and effective duration is the longest.Wind speed and traffic flow were the most relevant factors to the measured values ofη_a andη_PM at 1 hour.Wind speed had a positive effect on efficiencies and traffic flow had a negative effect.We recommend that a combined sprinkling-vacuum sweeping operation be conducted once in the morning and once in the afternoon during the non-peak traffic hours of the day,and a separate water-sprinkling or vacuum sweeping operation can be conducted before the morning peak and after the evening peak,which may achieve the optimum balance between economic cost and cleaning effect.