NMPB-Fer 1996
| Note - No printed guideline is available describing the NMPB-Fer 1996 method applied in France to railway traffic. This method, called „NMPB-Fer“, is a calculation procedure implemented only in the former French sound propagation software MITHRA using an emission data set provided by the French national railway institution SNCF. Thus, there is no detailed documentation on the NMPB-Fer emission model available here. |
Option „Tram“
This option determines what source height is used in the calculation (attribute TRAM):
- option activated: The source height is at 0.05 m above the railhead for all frequencies.
- option deactivated: The source height is at 0.8 m above the railhead for frequencies f <= 500 Hz, and at 0.05 m for frequencies f > 500 Hz.
Ground Absorption
This input box is just available when option „Tram“ is activated. The specified ground factor G (0<=G<=1, attribute BABS) is used provided the option „Railways are absorbing (G==1)“ on tab „Ground Absorption“ is activated (see Ground Absorption Tab).
In case the option „tram“ is deactivated gravel-ballast is assumed.
Note
With mixed traffic of normal trains and trams on the same track, either have to be modeled by distinct railway objects.
Emission Lw’
unweighted (linear) sound power level per unit length (1 meter) and per octave (for periods Day/Evening/Night)
Total-A
A-weighted sum level per period
vmax (km/h)
When specifying a track-relevant maximum speed vmax the train speed will be adjusted if necessary. In the calculation the smaller of both values is used.
Train Classes and Penalties
With this option activated, the types of trains and train classes, numbers of trains and corrections, can be edited locally, or an existing list with number of trains can be selected. CadnaA will automatically calculate the emission level from the specified values.
Note
The emission data for calculation according to NMPB-Fer is available from a file provided to customers separately.
For import of NMPB-Fer specific train classes (format „Mithra Trains“) see Special Formats.
Type of Track
Track Correction (dB): The entered value will be added to the emission spectrum (for all octaves).
Local Train List
Provided the train classes for NMPB-Fer have been imported the local train list can be edited.
Train Type
The train type is selected from the list Train Types on the Library (local)|Train Classes. By this selection all relevant parameters are specified.
Number of Trains Day/Evening/Night
Numbers of trains or units/vehicles during each period. With the same numbers for time periods D/E/N the same power level L’w,i D/E/N results (see also chapter NMPB-Fer 1996).
Speed v (km/h)
relevant speed of trains (in km/h)
Emission Lw,i (dB)
The emission level (sound power per unit length) L’w,i for a train class resulting from the specified parameter is displayed here.