Emission characteristics of road silt loading at the exit of typical construction sites in autumn in Tongzhou District, Beijing

In order to study the variation characteristics of road silt loading at exits of different types of construction sites, mixing stations and construction waste disposal sites, the road silt loading monitoring on exit roads of main construction sites (stations) and 137 conventional roads (referred to public roads that were not affected by construction sites, including urban roads and highways) were carried out in Tongzhou District, Beijing in autumn 2020. Dusts emission factors and emissions at exit roads of typical construction sites (stations) were calculated and analyzed based on AP-42 model. The results showed that the average silt loading of 100 m roads in two directions at the exits of different types of construction sites (stations) ranked as mixing station > construction waste disposal site > demolition site > housing construction site > water works site > landscaping site > traffic site. The average silt loading at 100 m roads in two directions at the exit of each typical construction site (station) was 1.3-21.1 times that of conventional road (0.59 g/m ²). The silt loading of the exit road of typical construction sites (stations) varied with the distance from the exit. There were obvious differences between different types of construction sites. PM₁₀ and PM_2.5 dust emission factors of 200 m roads in two directions of the exit were of 1.26-7.37 times higher than the background values, and the corresponding road dust emission was equivalent to an increase of 0.10-2.55 km of the road length at the background point, with the average value being equivalent to an increase of the corresponding road length by 1.16 km for each of the exit roads of 13 typical construction sites (stations). The spatial distribution of road silt loading and road dust PM₁₀ and PM_2.5 emissions at the exit and surrounding areas of all monitoring sites (stations) was lower in the north and higher in the south, and its influencing factors were closely related to the type and density distribution of construction sites (stations), the type of exit roads and vehicle flow.