| 4. |
Methods of Information Acquisition
for Planning (Nature measurements, Wind tunnels, Modelling) |
||
|
|||
.
|
4.2.4 Example Use – Small-Scale Dispersal (Tunnel Ventilation) Scenario 4.2.4.2 Methods In addition to data for the expected traffic densities and for air pollution levels in the initial pre-development state, basis data for meteorological conditions was also available. For the topographically varying area to be studied, long-term wind measurements were available from the German Weather Service (DWD), the State Institute for Environmental Protection (LfU), and the Urban Climatology Department of the City of Stuttgart Environmental Office. The dispersal of automobile emissions both from the tunnel portals and along the open stretches of road were studied in the wind tunnel at the Institute for Hydrology and Water Management at the University of Karlsruhe (LOHMEYER, 1989). The exhaust gas emissions were simulated through the release of a tracer gas in the affected road spaces. For reproducing the turbulence caused by the traffic, the method developed by ROMBERG et al. (1984) was employed, which simulated the movement of vehicles on the roads with a conveyor belt carrying small metal plates. The distribution of concentrations in the model could thus be measured at multiple points. Figures 4/20a and 4/20b contains sections from the wind tunnel model (1:250 scale) with corresponding measurement points. From the wind tunnel experiments, the NOx concentrations at the points of interest in the study area (denoted in white in Figures 4/20a und 4/20b) were obtained for a specified traffic density, wind velocity, wind direction, and development (initial or planned state). With the help of the wind statistics and the daily traffic count (i.e. daily emissions count), the yearly average value and the 98-percentile value (short-term value) of the additional and total NO2 levels were calculated. |
| . | |
| . .
|
|
|
||||||||
|
