A monitoring system to control effects and effectiveness of traffic measures in urban areas

The effectiveness of implemented traffic measures for a selected hotspot as well as the side effects were assessed by comparing modelling results based on identical input data but using traffic data without any measures in one case and with reduced traffic in the other case. The results emphasise the importance of a monitoring system that offers the possibility to assess and control the consequences of traffic measures within the entire road network. During the project, differences between results of the monitoring system and measurements were observed. It will be shown that these may be attributed to some degree to the emission factors of HBEFA 2.1 (INFRAS, 2004) which was used as the basis for emission modeling. Motivation European air quality limit values for PM10 and NO2 are still exceeded in a number of cities in Germany and Europe. Vehicle emissions have been identified to play an important role in these limit value exceedances. Thus, clean air plans are usually focusing on traffic measures to improve air quality. Typical measures are low emission zones, traffic bans for heavy duty vehicles, speed limits or road traffic reduction, with the spatial extent ranging from a single street section up to the entire city center. These measures may be installed either permanently or temporarily. In the context of quality assurance the effectiveness of the implemented traffic measures with respect to air quality improvement needs to be monitored. Additionally, it is important to control side effects on other street sections of the road network to prevent the emergence of new hot spots. In the case of an environmental traffic management system (ETMS), reliable traffic and air quality data are continuously needed as well (Diegmann and Gassler, 2009). However, measured air quality data is usually not detailed enough for these purposes due to the limited number of measurement stations available along the considered road network. Instead, a monitoring system based on a modelling system that provides concentrations within all relevant street canyons may be used to gain the necessary information on air quality along the road network.