A Modelling Chain for Establishing a Low Emission Corridor through the Alps

The main objective of the EU-LIFE BrennerLEC project is to implement and validate a set of dynamic traffic control policies on the A22 highway stretch between Bolzano and Rovereto, to provide environmental benefits in terms of air quality. The reduction of air pollutant emissions is pursued by means of the dynamic management of the maximum allowed speed limits (i.e., variable speed limits, VSL), according to the current and predicted air quality situation, to prevent environmental conditions which can cause negative effects on the health of the population living near the motorway. The estimation of NOx and CO2 emissions from traffic has been performed starting from an accurate characterisation of the vehicles fleet and traffic conditions on the A22 motorway. The combination of these data and the use of the European procedure COPERT V allow an accurate estimate of the emissions from traffic flowing on the highway. A forecasting system has been implemented: meteorological forecasts obtained by means of a numerical weather prediction system, WRF, are combined with a local steady-state dispersion algorithm to evaluate the dispersion processes and the pollutants concentrations. The modelling chain has been calibrated by means of air quality data measured during the past years in the study area. This forecasting system allows to predict, with enough time in advance, typically 24 hours, the occurrence of critical situations which require the introduction of reduced speed limits to reduce the air pollutants produced by traffic.