Keywords: dispersion models, simulation, exhaust gas measurements, traffic pollution, tunnel modelling, vehicle emissions, air pollution, environmental pollution, modelling, carbon monoxide, nitrogen oxides, NOx, valve control
Dispersion modelling near tunnel exits: simulation and measurements
Measurements of car exhaust gases were made in May/June 1995 in the vicinity of the Bielefeld tunnel. CO and NOx from car exhausts were measured to allow comparison with a model simulation. Ozone was also measured. These measurements were made using commercial continuous analysers. A valve control system was used to investigate the dispersion of the trace gases. This allowed measurements at up to 15 locations within a short period. Thus only one analyser was required for measurements at all 15 points. Following the measuring campaign the topography in the vicinity of the Bielefeld tunnel was digitised. A flow and dispersion model called MISCAM (Micro Scale Air pollution Model) was then utilised. Results from the simulation were compared with the measurements. Comparison of the measurements with the simulation validate the simulation results for inert trace gases such as CO and NOx. The deviation between measurements and simulation is about 16%.