High concentrations of air pollution can build up around tunnel entrances. In order to limit these and to predict the impact of measures, VITO has developed a unique air quality model.
The exits of tunnels are often equipped with protective infrastructure such as screens (which also suppress traffic noise) and raised verges to limit the impact on the environment.
In the case of new tunnels, depressed tunnel exits can be chosen. However, this is always done on an ad hoc basis: the impact on local air quality at the exit of each tunnel is calculated and analyzed separately. The way this is done – most often by means of complex 3D simulation models – is a time-consuming and not very cost-effective approach.
VITO has therefore developed a unique generic model, commissioned by the Flemish government's Department of the Environment, that can be used as a means of quickly calculating the impact of tunnels on local air quality. The model provides an estimate of the pollution to be expected at the exit of the tunnel, based on data such as the dimensions of the tunnel and the traffic flow. Additionally, the impact of measures to limit the impact on the air quality in the surroundings can be modeled.
For the development of the mode VITO air quality experts worked together with tunnel engineers from Tractebel Engineering. The future users of the model will primarily be environmental impact assessment (EIA) experts and consultancy firms commissioned by project developers.
The new model is a MS Excel application built on top of a database with the outcomes of a 3D CFD pollutant dispersion calculation for all tunnel parameters and mitigating measures.
Client: Flemish Department of Environment
Year: 2019 – 2021
