Estimating Road Transport Pollutant Emissions Under Traffic-Congested Conditions with an Integrated Modelling Tool—Emissions Reduction Scenarios Analysis

This study aims to investigate, in microscale, the pollutant emissions due to road traffic under traffic-congested conditions at street level and the impacts on air quality of traffic emissions reduction scenarios by applying an Integrated Modelling Tool (IMT) for a main road axis in Thessaloniki, Greece. ΙΜΤ links a real-world traffic model, a dynamic emissions model and a Lagrangian dispersion model coupled with a boundary layer flow module. Pollutant emissions from cars at edges with traffic lights were + 30% higher than those estimated at other edges while NOx emissions were + 22% higher at the edges with bus stops. A comparison of the IMT and COPERT Street Level emissions results showed that the IMT emissions were higher than the COPERT Street Level emissions for roads with traffic lights or bus stops, characterized by high variability in vehicle speed per second due to stopping and accelerating. This resulted in up to 2 times higher NOx emissions. IMT was applied to assess the impact on the atmospheric environment of the redesign of the road axis promoting sustainable urban transportation. A reduction by − 20% of the cars and motorcycles traffic flows in combination with the increase by a factor of 2 of the frequency in the circulation of city buses replaced with battery electric vehicles will result in lower pollutant and CO2 emissions ranging from − 29 to − 41%. Reductions of about − 65% in the road traffic NOx maximum concentration levels were also estimated.