TNM
By default, all available settings listed below are deactivated.
All Emissions at 0.1 m above road surface
The emission model of TNM considers - depending on the type of source - several emission heights. Activating this option will level down all types of sub-sources to a common height of 0.1 m above road surface.
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| option deactivated: up to 3 sub-sources visible on the vertical grid (at 0.1/1.5/3.66 m) | option activated: just a single source height at 0.1 m(for both: Adiv based on 3D-distance) |
Use 3D-distance for calculation of Adiv
In TNM, the geometrical divergence is calculated based on the 2D-path length in xy-plane only. This causes the receiver level not depending on height (i.e. level is not decreasing with receiver height). By activating this option calculated levels will depend on receiver height or height of grid points.
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| option „3D-distance for calculation of Adiv“ deactivated (i.e „strictly accord. to TNM“) |
option „3D-distance for calculation of Adiv“ activated |
Correct bug in Fresnel-zone-calculation
In TNM 2.5-code a sign error in the calculation of Fresnel zones was discovered altering calculation results reasonably. With this option activated the Fresnel-zone-bug will be corrected for in CadnaA-TNM.
Note
In case results shall be compared with results obtained by TNM 2.5 software this option should, however, be deactivated.
Additional Information
In order to obtain correct results in comparison with the release 2.5 of the TNM software further configuration settings are to be respected. Those are described below.
Ground Absorption
Regarding the ground attenuation, the settings (on Calculation| Configuration menu, tab "Ground Absorption") are based on the ground absorption factor G of ISO 9613-2 ISO-9613-2-1996. For the time being, the following airflow resistivities refer to the ground absorption factor G:
| Airflow Resistivity (in rayls) |
Ground Absorption Factor G (ISO 9613-2) | TNM-specific ground type |
|---|---|---|
| 20000 | 0 (i.e. reflecting) | pavement |
| 1000 | 0.33 | *) |
| 600 | 0.5 | *) |
| 400 | 0.67 | *) |
| 300 | 1 (i.e. absorbing) | lawn |
*) These ground types are not available in CadnaA for the time being.
In addition activate the option „Roads/Parking Lots are reflecting (G==0)“.
Note
The latter setting will - in conjunction with the additional width from self-screening (see below) - ensure that the entire road width as considered by TNM is reflecting (and not just the region between the emission lines).
DTM: Explicit Edges only
Activate on the Calculation|Configuration option „Explicit Edges only“, „DTM“ tab (see DTM Digital Terrain Model Tab).
Note
TNM 2.5 software just triangulates between „real“ terrain contours, not using the heights of objects (e.g. roads and barriers with absolute heights). For this reason it is required that the geometry of all objects is imported additionally as terrain contours or heights points, as otherwise they will not influence the resulting terrain shape.
Self-Screening of Roads
Activate for all types of roads the option "Self-Screening" (dialog Road| Geometry) and enter an additional width of 1.83 m (6 feet).
Dialog Road\:Geometry: self-screening with additional width left/right of 1.83 m
Note
Changing the attribute’s values for all roads in a project is achieved conveniently via the dialog Modify Objects|Modify Attribute, for attributes SCCR_AW_L and SCCR_AW_R, respectively.
Temperature and relative Humidity
The general settings for the temperature and the relative humidity in CadnaA match with the default settings in TNM 2.5-software (see menu Calculation|Configuration, tab "Industry"):
- 50% relative humidity
- temperature 20°C
Restrictions
The following features of the TNM-software are not implemented in CadnaA for the time being:
- no TNM-specific parallel barrier analysis,
- no accelerating ramps and flow control devices, and
- no import of TNM-files.
Note
The “Pass-By of individual Vehicles” function is not available when the TNM standard is used (see Pass-By of individual Vehicles).