A proportional impact assessment approach that uses traffic models to screen infrastructure alternatives before detailed air quality and noise modelling.
Large infrastructure projects often require the comparison of numerous alternatives. In early planning stages, detailed air quality and noise modelling for every alternative is not always feasible or necessary to identify meaningful differences in liveability impacts. This presentation introduces a method that translates traffic model outputs into a structured screening of potential air quality and noise effects. The approach was applied in the Viaduct Gentbrugge Project (Belgium), where 26 infrastructure alternatives were assessed. The method uses changes in passenger-car-equivalent kilometres travelled per day (PCE-km/day) as a proxy for the potential liveability impacts of road traffic. Traffic changes are combined with population exposure by weighting results according to population density at the level of statistical spatial units. The methodology distinguishes between local roads and highways. For highways, impacts are assessed within a 500-metre buffer to reflect their wider influence on surrounding communities. Specific provisions were also developed for tunnels and tunnel mouths. The presentation demonstrates how this approach not only ranks alternatives through an overall score but also identifies local deterioration through sub-area scores and a correction mechanism for pronounced negative impacts. The result is a transparent and reproducible framework for proportionate alternative screening, enabling to focus detailed air quality and noise modelling on a limited number of reasonable alternatives in subsequent planning or EIA stages.
Paul Arts is a senior EIA consultant at Antea Group Belgium, specialised in infrastructure projects where traffic modelling supports evidence-based decision-making.