Effects of the manual and electronic toll collection systems on the particulate pollutant levels on highways in Taiwan

Few studies have quantified the effects of particulate air pollution reductions on electronic toll collection (ETC) and manual toll collection (MTC). Our study evaluated the levels of particulate pollutants, including particulate polycyclic aromatic hydrocarbons (p-PAHs), PM1.0, PM2.5, and PM10, from MTC and ETC systems in booths at a manual/electric hybrid toll station on a highway in Taiwan. A two-week sampling campaign was conducted at the toll station on the first highway in the Taipei metropolitan area. Indoor tollbooth monitoring samples were collected for the ETC and MTC lanes to assess the hourly p-PAH, PM1.0, PM2.5, and PM10 concentrations. The hourly average particle concentration was calculated for different types of toll collection based on 100 vehicles per hour. The average traffic density in the truck and bus lanes or car and van lanes with ETC was significantly higher than that with MTC. The mean p-PAH, PM1.0, and PM2.5 concentrations in the car and van lanes with MTC were higher than those for ETC. The increases in PM1.0 and PM2.5 concentrations per 100 vehicles in the bus and truck lanes with MTC were approximately 2 times greater than those for ETC. ETC technologies serve as a solution to traffic delay problems at toll stations in Taiwan and may more homogeneously reduce the levels of pPAHs, PM1.0, and PM2.5 particulate pollutants from traffic emissions than the MTC along highways.