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RLS-90

Dialog Configuration, tab „Road“ for RLS-90(with option „strictly accord. to RLS-90“ deactivated)

Strictly according to RLS-90

With the check box „Strictly according to RLS-90“ activated, CadnaA calculates using the following settings:

  • only the first-order reflections, irrespective of the order of reflection specified on the „Reflection“ tab,
  • no lateral diffraction at obstacles,
  • no attenuation due to foliage and built-up areas,
  • no consideration of the receiver directivity,
  • no meteorological correction, and
  • the two outermost lanes of a road are calculated as separate line sources with a height of 0.5 m above road.

Note

All other settings made on the „Reflection“ tab, "Conditions for Calculation of Reflection", such as the search radius for reflecting objects, will apply even when the option „Strictly according to RLS-90“ is activated (see Reflection Tab).

Calc exactly one reflection order

With this option deactivated the maximum order of reflection is specified via the „Reflection“ tab (see Reflection Tab).

No Lateral Diffraction

When this option is deactivated the lateral diffraction will be considered which is normally not the relevant to the receiver level due to the extension of the road sources (line sources) in normal situations.

no lateral diffraction by default, option „Strictly according to RLS-90“ activated (short road section) with lateral diffraction, option „Strictly according to RLS-90“ and „No Lateral Diffraction“ deactivated

No Housing Attenuation

By default, the attenuation by built-up areas is not considered by RLS-90. When this option is deactivated the CadnaA-object „Built-Up Area“ causes a screening effect.

Note

The housing attenuation DG is calculated accord. to VDI 2714 (see Built-Up Areas and Foliage). This value is not displayed on the calculation protocol in a separate column (see CadnaA-manual „Attributes, Variables, and Keywords“, Protocol attributes).

No Foliage Attenuation

By default, the attenuation by foliage is not considered by RLS-90. When this option is deactivated the CadnaA-object „Foliage“ causes a screening effect.

Note

The attenuation due to foliage DG is calculated accord. to VDI 2714 (see Built-Up Areas and Foliage). This value is not displayed in a separate column on the calculation protocol.

Calc outer Lanes separately

By default, the center lines of the outermost lanes of a road are the emission lines in RLS-90 (at a height of 0.5 m). When this option is deactivated just the road’s center line represents the emission line.

vertical grid, perpendicular to the road’s axis: option „Strictly according to RLS-90“ activated vertical grid: option „Strictly according to RLS-90“ and „Calc outer Lanes separately“ deactivated

No Meteorology (Cmet see Industry)

No meteorological correction is established by RLS-90. In CadnaA, nevertheless, the meteorological effect can be considered by deactivation of this option. In this case, the settings on the list box „Meteorology“ on the „Industry“ tab are relevant.

Note

The value of Cmet will be calculated according to ISO 9613-2. This value is not displayed on the calculation protocol in a separate column.

see also ISO 9613 (1996) and ISO 9613 (2024)

Calculation accord. to VBUS

relevant for Germany only!

The German guideline VBUS is selectable on the „Road“ tab with RLS-90 selected. The main modifications compared to the original procedure from RLS-90 are:

  • The setting for lateral diffraction is not possible any longer.
  • The calculation includes the meteorological correction Cmet (C0 for Day/Evening/Night is 2/1/0 dB).

Note

When not considering Cmet and with the same emission D/E/N a level difference between Lden and Ln of 6.395 dB results. Since Cmet is automatically taken into account in CadnaA, the difference is usually smaller than this value.

  • From MDTD values the number of vehicles per hour M (Day/Evening/Night) are calculated according to VBUS (different from RLS-90).

Displaying the value of Cmet

The value of Cmet when calculating road noise accord. to RLS-90 can be displayed for raids with a road width of 0 m. Different values result for the two emission lines of roads with a finite road width (the values of which, however, cannot be displayed using the procedure described in the following).

Proceed as follows:

  • First, deactivate the option „No Meteorology (Cmet see Industry)“ and enter - for example - the following values for C0 on the „Industry“ tab: D/E/N = 3/2/1 dB (for ISO 9613).
  • Activate the option „Write Protocol“ on the Calculation|Protocol menu.
  • Start the calculation by clicking on the pocket calculator symbol on the toolbar.
  • Open the protocol via Calculation(|Protocol menu, button „Print“|Preview“.
  • When subtracting the individual attenuation terms from the emission value you will appreciate that not the receiving level as shown results, but that for every segment a difference remains.
  • In order to display this difference on the protocol the road source is converted into a line source (via the dialog Modify Objects|Convert to, „Road“ into „line Source“).

With this, the emission parameter will be converted according to:

\(L_{wA}''=L_{m,E}+19.2\:dB\)

As the source height of the road is 0.5 m above ground, the line source needs to get lifted up to 0.5 m first.

  • Open again the dialog Modify Objects|Modify Attribute for the object „Line Source“ and click OK.
  • On the dialog Modify Attribute, select the attribute HA form the list box and enter for „Arithmetic|New Value“ 0.5 m.

After click on OK the relative height of the line sources is set to 0.5 m.

  • Start the calculation by clicking on the pocket calculator symbol once more.
  • Open the protocol (Calculation|Protocol menu, button „Print“|Preview“).

The values for Cmet displayed on the protocol are those relevant for the road noise calculation. The receiver level and the further attenuation terms displayed on the protocol are, however, not relevant as the result from ISO 9613-2 and not from RLS-90.