Validation of a street canyon model in two cities

A street canyon model has been formulated based on work published by Hertel and Berkowicz. An outline is given of the theoretical approach used, followed by a modelling of nitrogen oxides and carbon monoxide measurements from sites at Cromwell Road, Central London and Stratford Road, Birmingham Modelled concentrations were compared with observed mixing ratios for both sites. AT Cromwell Road, good agreement was achieved for one month but which was not reproduced as well for the other two months tested. There is uncertainty as to the effect of one of the side streets and whether the general flow is altered during periods of marked solar heating. Also emissions from vehicles may vary from those assumed. The interpretation of the Stratford Road site's results was less straightforward with complications concerning background pollutant levels and changes in emissions from interrupted traffic flow.