Ralf-Peter Schäfer

An integrated simulation system for traffic induced air pollution

Abstract In recent years the growing traffic demand combined with an increase in exhaust gas emissions is the main reason for a permanent decrease in air quality in urban areas. Especially during hot summer days, mainly traffic emissions are responsible for providing precursor substances for the ozone reaction. They account for approximately 70% of all emissions. In order to facilitate investigations analysing this situation, local authorities in environmental protection and urban planning agencies are interested in performing emission and air pollution simulation as well as scenario analysis by means of model based simulation systems. Therefore a realistic modelling of the physical behaviour of the atmosphere as well as the exact description of the emissions is necessary. Up to now mainly traffic countings combined with different statistical methods have been used to calculate these emissions. The obtained results are often incorrect and do not reflect the dynamic behaviour of the traffic flow. Traffic flow models provide a more promising approach. Currently, in the European Community funded SIMTRAP project, an integrated system for traffic flow information, air pollution modelling and decision support will be developed in a distributed High Perfomance Computing Network (HPCN), and subsequently tested in a number of European sites. SIMTRAP centres around two well-established core components: the air pollution model DYMOS and the mesoscopic dynamic traffic simulation tool DYNEMO. The project aims to integrate both modules in a remote HPCN environment in order to enable the detailed simulation of an area of sufficient geographical extent. Interpretation and visualization of results will take place in a local 3D GIS system. Communication will take place using existing computer networks and protocols.

Simulation of traffic-induced air pollution for mesoscale applications

Recent investigations have shown that vehicular traffic is the main source for emissions leading to summer smog. A study of the impact of traffic emission on urban air quality requires a complex air-pollution simulation system. This paper presents results of the development and application of an air-pollution simulation system at GMD FIRST which aims at supporting users in government administration and industry with forecasting and operative decision-making as well as short- to long-term regional planning. The components of the simulation system are parallelly implemented simulation models for meteorology, transport and air chemistry, data bases for model input and simulation results, as well as a graphic user interface for spatial data visualization. In order to study the influence of traffic emissions, a traffic-flow and a traffic-emission model have been added to the simulation system. Results presented are from two recent applications in the regions of Berlin/Brandenburg and Munich (Germany). Further applications are in preparation.

Simulation of air pollutant dispersion on parallel hardware

Abstract This paper deals with the analysis and simulation of air pollutant dispersion in the region of Berlin. Results from simulations of a winter smog episode are presented. A concept of a simulation package for summer smog consisting of a complex meteorological model, an air chemistry model, and a dynamic model of emissions for data input is described. It is pointed out that a system of such numerical models is very complex. Simulation runs and scenario analyses take hours of computing time, even on todays supercomputers. Therefore a strategy for model decomposition and implementation on massively parallel computers is described. As an example this is carried out on one particular atmospheric model.

Traffic Jam Warning Messages from Measured Vehicle Data with the Use of Three-Phase Traffic Theory

Based on Kerner’s three-phase theory, we study an algorithm for the generation of traffic jam warming messages from measured GPS and GSM probe vehicle data that have been collected in TomTom’s HD-traffic service both from nomadic devices and vehicle’s embedded systems. We find that the data allows us to reconstruct the structure of congested traffic patterns with a much greater quality of spatiotemporal resolution than has been possible before. It occurs that congested traffic in measured traffic patterns consists of the two traffic phases of Kerner’s three-phase theory, synchronized flow and wide moving jams. The application method distinguishes between the fronts of the congested traffic phases, wide moving jam and synchronized flow. It will be shown that a penetration of about 2% of the total traffic flow is enough to implement a precise traffic jam warning message for navigation systems.

EffizienzCluster Logistik Ruhr, DiNav – Dynamics in Navigation

The project “Dynamics in Navigation” focuses on improving the routing of personal navigation devices (PNDs). To achieve this goal a central and independent service has to be set up. A service providing not only data about the actual traffic situation but also traffic forecast as well as information about the roads’ spare capacities. Based on this information, route choice can dynamically adapt to the current and forecasted traffic situation. In addition to that, this approach also offers the possibility to respect route recommendations and traffic management strategies by local authorities. By all these means we expect a more efficient usage of the road network and lower travel times.

High-Performance Parallel Computing for Analyzing Urban Air Pollution

The paper deals with results and experience of research work in the field of air pollution modelling and simulation. An air pollution simulation system consisting of models for meteorology, air pollutants transport and air chemistry is described. The computational aspects implementing numerical models as part of the simulation system are discussed with emphasis on parallel computing. An application example of the air pollution simulation system is presented.