The purpose of the study was to calculate effects of traffic light controlled intersections in the centre of the city Ústí nad Labem on quantity of produced emissions by vehicles. The assessment was carried out by means of micro-simulation of traffic flow at selected intersections in the city centre, including evaluation of congestion lengths and time delays of passing the intersection. The contractor was the city of Ústí nad Labem, the project was finished on 10/2006.