Optimisation of Modelling Methods for Traffic Pollution in Streets. TRAPOS

The TRAPOS (Optimisation of Modelling Methods for Traffic Pollution in Streets) Project was a European Research Network that had two main objectives: 1) To contribute to scientific achievements in the development and improvement of modelling tools used for the prediction of traffic pollution in urban streets through co-operative work. 2) To promote training-through-research, especially of young researchers, within the framework of high quality trans-national collaborative research projects The project was in the framework of the European Commission’s Training and Mobility of Researchers Programme (TMR), was co-ordinated by the Danish National Environmental Research Institute (NERI) and ran from November 1997 until April 2001. This summary and available CD has been distributed to some researchers in Europe. Several of them suggested that others may be interested in the project and that led to this note and contact points. The Network's participants represented universities, public research organisations and commercial consulting companies from several European countries (Denmark, France, Germany, Greece, Switzerland, the Netherlands and the United Kingdom). Their fields of research covered several different aspects of air pollution modelling, such as: laboratory wind tunnel modelling, field measurements, dispersion modelling including computational fluid dynamics and the regulatory applications of models. The work within the TRAPOS Network was closely connected with many other European projects and research activities conducted by the participants. The interdisciplinary character of the co-operation among the participants represented diverse experience and working methods and this led to efficient utilisation of the results and scientific achievements. Traffic pollution modelling is a very broad area and, to narrow the scope of the work within the Network, some principal research areas were identified as priorities: • the traffic created turbulence and its influence on dispersion of pollutants in the street, • the influence of thermal effects on flow modification within street canyons with special regard to low wind speed conditions, • the sensitivity of the flow and turbulence characteristics to the architecture of the street and its surroundings, • the fast chemical processes with special regard to NO-NO2 conversion, • the dispersion and transformation processes of Respirable Suspended Particulate (RSP) matter. Making use of the existing facilities and expertise of the participants, the activities contributing to the research objectives were: • field measurements and analyses of data, • laboratory (wind tunnel) measurements, • model evaluation and inter-comparison. The models in use within TRAPOS covered both simpler, parameterised models and more advanced Computational Fluid Dynamics (CFD) models. Synergy in the work with different types of models ensured scientific quality and the practical applicability of the results. Field measurements and wind-tunnel data were used for evaluation and improvement of mathematical models. Wind-tunnel models were also tested against data from field measurements. Results from CFD models were used to improve parameterisation of simpler semi-empirical models. Design of new field experiments and also wind-tunnel measurements were guided by results from mathematical modelling. In order to facilitate the joint work a number of Working Groups were created to focus on each of several activities of the Network. These Working Groups, which were led by the young researchers, accepted the main responsibility for the organisation of the work within TRAPOS. Especially dedicated web-sites, with presentation of the results and conclusions, were established by these groups (http://www.dmu.dk/AtmosphericEnvironment/trapos/wg.htm). Based on the achievements and conclusions provided by the Working Groups a CD was put together for distribution. This included: Chapter 1 deals with the processes influencing dispersion in a street environment. Theoretical and experimental studies of these processes were the main subject of TRAPOS. Beside the more traditional aspects, such as the influence of the street architecture on the dispersion conditions, this chapter covers also some special phenomena, which have not been studied in such details previously. These include traffic produced turbulence and effects of surface heating. Presentation and discussion of the different tools used within traffic pollution modelling is given in Chapter 2. This chapter covers the use of laboratory wind tunnels and the use of CFD modelling. An extensive CFD model evaluation study was conducted within TRAPOS. The data used for this evaluation study originated mainly from systematic wind tunnel experiments but field data were also used. In Chapter 3 the application and evaluation of different modelling methodologies for a practical traffic pollution study is presented. This study, the so-called "Podbielski exercise", was initiated and conducted by German institutions but with a very active participation of TRAPOS. A summary and overview of the TRAPOS Network and its achievements is given in Chapter 4. The achievements of the TRAPOS project were frequently presented at several major Air Pollution conferences and published in the open literature. In March 2001 the Third International Conference on Urban Air Quality was held in Loutraki, Greece. This conference provided an excellent opportunity to present some the results of the Network to a broader community. The Extended Abstracts of presentations given by TRAPOS participants at this Conference are attached to this publication as Chapter 5. The reference list of all papers published during TRAPOS is given in Chapter 6. The Appendices provide organisational details of the Participants and the list of the Young Visiting Researchers employed by the network.