气候变化领域集成服务门户

Rail yards are important nodes in the freight transportation network. However, they are also a focus of public health concern when located in highly populated areas. Field characterization of near-rail yard air quality is challenging due to spatially- and temporally-variable emissions. Numerical models can provide valuable insight into factors affecting emission dispersion and resulting near-field air pollution. This study utilizes computational fluid dynamics (CFD) modeling to investigate near-field air pollution surrounding a generic, moderate-sized intermodal rail yard with emissions of a neutrally buoyant gaseous pollutant. Rail yard and surrounding neighborhood structures were added in succession to a base case to study the influence of surface roughness on the generic pollutant's spatial concentration profile. A spatially weighted emissions scenario revealed highly variable pollutant levels in downwind neighborhoods, strongly affected by wind direction. Rail yard topography resulted in a modest increase in near-field pollution levels. Densely located two-story homes surrounding the rail yard reduced downwind concentrations by 16% and 15% at 25 m and 100 m downwind of the rail yard boundary, respectively. A 6 m boundary wall surrounding the rail yard, with four open sections enabling traffic flow, reduced downwind pollution levels by 25% and 12% at 25 m and 100 m downwind, respectively. While average pollution levels were lower with the addition of neighborhoods and a surrounding boundary wall, high spatial variability in pollution levels resulted in some near-field areas experiencing increased pollution that are offset by reductions in other areas. Copyright (C) 2015 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V. All rights reserved.