New motorways, bypasses and traffic management schemes give rise to changes in traffic flows which have a consequent effect on the concentration of air pollutants nearby. As there is increasing public concern about the possible effects of air pollutants from vehicles on health, it is necessary to estimate the concentrations of air pollutants as part of the assessment of the scheme. A method of estimating the maximum levels likely to be experienced at a given receptor close to a road network has been developed and it is intended to be used to indicate areas where atmospheric pollution may be a problem. The method is described through an example. When a problem area has been identified more detailed investigation can be carried out, using information readily available to the highway engineer. The inputs required for the computer program are traffic flow, traffic speed, road layout and simple meteorological data. It is recommended that the estimates are made for the 'before' and 'after' situations so that pollution levels at sensitive locations can be compared. Where this cannot be done predicted values can be related to air quality data and an additional computer program used to estimate the distribution of pollutants likely to occur, so that the frequency of occurrence of high concentrations can be assessed. The methods predict concentrations of carbon monoxide: information on levels of hydrocarbons, oxides of nitrogen and lead can be obtained from relationships described in the paper (a) for the covering abstract of the proceedings see IRRD 274491.
Samenvatting