PROKAS

Intended field of application

PROKAS is a model to calculate the air pollutant concentrations caused by a net of streets.

Model type and dimension

Emission model according to German Emission Factors Handbook coupled with Gaussian Dispersion Model.

Model description summary

PROKAS_V is a model based on the German guideline VDI 3782/1 "Gaussian Dispersion Model for Air Quality Management". Modelling of up to 5000 line sources (reproduced by sets of point sources) of a network of streets is possible. The influence of traffic induced turbulence, the influence of the course of streets on dams and the influence of noise protection devices for each street are included.

An interface exists to MOBILEV (program for determination of traffic induced emissions), to PROKAS_B and to WinMISKAM (programs for determination of concentrations in built-up streets).

Input requirements for PROKAS_V are

• files containing the co-ordinates of the streets, the annual mean of the emissions of up to 3 air pollutants, for example benzene, soot, and NO_x in these streets, and for each street additional terms to the dispersion parameter counting for near field disturbances of the flow (traffic induced turbulence etc.)
• the Gaussian dispersion parameters for smooth and rough terrain
• the co-ordinates of the receptor points and the background concentrations at these points
• the distribution of the emissions for the single hours of the week
• the meteorological statistics (3-dimensional statistics of wind speed, wind direction and atmospheric stratification)

The model determines the concentrations (annual mean values and 98-percentils) of the air pollutants under consideration (incl. NO_x and NO₂) at arbitrary receptor points.

Model limitations PROKAS-V

PROKAS_V is not applicable

• if the wind field is inhomogenious in the area under consideration or in areas with valley drainage flows
• in cases when the influences of buildings have to be considered in detail
• in distances less than 10 m from the line source.

In the case the air quality demands a more detailed approach PROKAS_B is used

PROKAS_B is an additional module to PROKAS_V. It calculates the concentrations in built-up streets caused by the emissions in these streets while PROKAS_V provides the contributions of the surrounding streets. PROKAS_B is based on precalculated dimensionless results with the microscale flow and diffusion model WinMISKAM for 21 building patterns. These patterns depend on the ratio of height of buildings to width of street, presence of buildings on one or both sides of the street, and the percentage of gaps along the length of the street. Modelling of up to 5000 streets with the surrounding buildings within a network of streets is possible. The influence of traffic induced turbulence is included. An interface exists to MOBILEV (program to determine traffic induced emissions).

The calculated results are the concentrations (annual mean values and 98-percentils) of the air pollutants under consideration (incl. NO_x and NO₂) in 1 m distance from the walls of the surrounding buildings and at 1.5 m height above the ground for the side of the street, where the meteorological conditions result in the highest concentrations.

Model limitations PROKAS-B

PROKAS_B is not applicable

• if the building patterns vary strongly within 100 m along the street
• if the assumption of neutral atmospheric stratification in the street is not appropriate or in areas with valley drainage flows
• in cases when the influences of buildings have to be considered in detail.

PROKAS_V and PROKAS_B are applicable on common PCs under Windows 3.xx, Win9x or Windows NT.

Further information see: Model Documentation System, www.sfi-software.de or from  Ingenieur-Büro Lohmeyer  Karlsruhe, Germany.

Last updated: 11.02.2001. Next update scheduled: Not scheduled at this time.