Gas-protective efficiency of strips of green plantings on objects of transport infrastructure

Defining the geometrics and structure of linear and strip composite urban green belts of aesthetic and environment-protection functions intended for transportation infrastructure facilities in urban planning zones and historic centers in densely built-up areas intensely used by transportation services. The observations were made in streets of major cities and on physical models of buildings and green belts of three degrees of density, from dense to permeable. The dependence of air-pollutant shielding efficiency of green belts on their density and height has been determined. Vertical concentration fields on the street cross-section have been obtained by physical modeling, and consistent patterns of car emissions dispersion by shelterbelts of various structure have been found. The lowest car emissions concentration behind green belts is observed at a distance equaling h (belt height) to 1,5 h , where the pedestrians move; the highest, at a distance of 2 h to 3 h . To effectively protect the pedestrian ways and the areas along the road from car emissions, dense and evenly semi-open shelterbelts, 15 to 30 m wide should be used. If the width of the road dividing strip is limited, shelterbelts with the openness factor of 0,5 to 0,6 should be used. The plant rows closest to the road should consist of shrubbery making a two-storey hedge, and of low-crown trees, with the further rows increasing in height.