Parallel parking improves air quality on urban pavements

Walking is good for health and does not contribute to greenhouse gas emissions. However pedestrians still are exposed to pollution emitted by drivers.

Urban planning can reduce the level of pollution that pedestrians are exposed to through congestion charging and intelligent transport systems. However, some pollution can also be prevented from reaching pedestrians simply by introducing barriers between the pavement and the road.

According to empirical evidence from Trinity College Dublin, less pollution reached the pavement when cars were parked sideways on, rather than at an angle to the street.

The researchers investigated how different on-street parking layouts would affect pollution dispersion. They used computer modelling to simulate a street canyon in which cars were either parked parallel to the pavement, at a 45 degree angle or at a 90 degree angle.

The best results were obtained in the street canyon with parallel parking bays, which reduced pedestrian exposure to pollutants by 31% and 49%, depending on the wind direction.

Results from this new series of studies may help urban planners design more pedestrian-friendly streets.

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Source: Gallagher, J., Gill, L.W. & McNabola, A. (2011). Optimizing the use of on-street car parking system as a passive control of air pollution exposure in street canyons by large eddy simulation. Atmospheric Environment. 45(9):1684-1694. Doi: 10.1016/j.atmosenv.2010.12.059.