Effectiveness of street sweeping and washing for controlling ambient TSP

Effectiveness of street sweeping and washing (S/W) for controlling ambient “total suspended particles (TSP)” was evaluated by TSP measurements and determining silt load from active traffic streets. A modified regenerative-air vacuum sweeper (RAVS) and a washer were used in this study. The sweeper made a pass followed by the washer. The S/W efficiencies (ηs,ηT) were obtained based on the experimental data of silt loading and TSP. It was found that the direct impact of sweeping on ambient TSP emissions was short-lived lasting no more than 3-4 h. When a vacuum sweeper and a washer, respectively, did a good job collecting or cleaning the visible fine particles on roads, the method of S/W tested in this work was effective at removing the sources of the road dust particles. This paper concludes that street sweeping followed by washing was found to offer a measurable reduction in TSP emission potentials. Typically, the reduction efficiency of ambient TSP is up to 30%. Finally, correlated with ηS (based on silt loading), a useful equation is proposed to estimate the S/W efficiency, ηT (based on TSP) with a standard error of ±20%. It seems feasible to predict the reduction efficiency of ambient TSP controlled by the regenerative-air vacuum sweeper and washer used in this work for engineering applications. Effects of traffic volume and wind velocity on the S/W efficiencies are also discussed in the paper.