The environmental impact assessment of road schemes: with special reference to air quality in Lancashire

Abstract

Environmental Impact Assessments and Environmental Statements provide the decision making process with environmental information, in order that a balanced decision may be made by considering environmental as well as economic and social impacts. The credibility of the entire process stands on the ability of the predictive techniques to accurately predict possible impacts. This thesis examines the quality of one predictive technique, the air quality assessment of road schemes, in an attempt to identify areas of deficiency and ways by which the technique can be improved.
Analyses of Environmental Statements (ES5) have shown that they are generally of poor quality and so do not fulfil their potential as an environmental management tool. This study has shown that the air quality aspects of ESs were of poor quality and that the current DOT method for assessing air quality was inaccurate at the sites tested.
Vehicle emission modelling before and after the opening of the Freckleton Bypass indicated that the network total masses of carbon dioxide, carbon monoxide, hydrocarbons and lead were less in the "after" situation compared with the "before, and that the oxides of nitrogen were slightly more, due to the increase in average speed.
Average concentrations of nitrogen dioxide, total suspended particles and the average number of carbon monoxide air quality standard violations monitored on the bypassed route were less in the 'after situation than in the "before" Work conducted during this study would also suggest that emissions tend to build up around the road from where they are emitted when the wind speed is approximately 1.5 m/s or less, which can result in potentially dangerous air pollution episodes. Also that meteorological data from weather stations cannot directly be used for traffic air quality modelling without further research being conducted.
The main future uses of air quality modelling are as an environmental management tool to try and avoid potentially dangerous pollution episodes and to assess the impacts of traffic management as well as road building proposals.