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Entering Road Geometry

The noise emission of the parametric source „road“ depends on the selected road noise standard (menu Calculation|Configuration, source group „Road“).

In the following, the European calculation procedure „CNOSSOS-EU“ is selected as road noise standard.

Entering a road

Upon selection of the road symbol from the toolbox the road can be entered as a polygon line.

  • Select the object "Road" from the toolbox (symbol: ).

  • Select a scale of 1:1000 and click with the mouse in the left part of the main window to define the first polygon point of the road.

  • Move the mouse to the right and click to a second location.
  • Click the right mouse button to finalize the input road.

  • Change to the edit mode by clicking the arrow in the left top corner of the toolbox.

  • Double-click with the mouse on the axis of the road. The dialog Road for RLS90 opens.

Dialog Road (for CNOSSOS-EU), with „Exact Count Data“ selected

Specifying road width

There are three ways to specify road width:

  1. Specifying the distance between the center lines of the outer lanes:To this end, enter in box "SCS/Distance (m)" a numerical value. With that width being zero the road will be modeled by just a single emission line.

  2. Specifying the distance of the road’s curb-to-curb distance:In some road noise standards, the road width is defined starting from the curb. This option is available as a second option when clicking on the file selector symbol . In this case, the emission lines are located at half the value of the additional width as defined on the dialog Options|Appearance for the object type "Road" (default value: 3.5 m).

  3. Selecting of a default cross-section according to the German „RAS Q 82 + 96“ (see RAS-1982 and RAS-1996 in the CadnaA reference manual):Furthermore, various cross-sections are available via the file selector symbol resulting from German road construction guidelines. Select a cross-section using the mouse and click the OK button.

In all three cases the dotted line/s represent the emission line/s. By default, the road curb is drawn as full line while the overall road’s axis is drawn as a thick dotted line. All appearance settings can be modified on the dialog Appearance (Options menu) via the object types "Road" and "Road 2" .

Note

All settings defined for the Object „Road“ on the dialog Appearance concern merely the graphic representation and are not relevant to the location of the emission lines.

The distance from the road axis to the curb (additional width) is set via object type „Road" stopped with a default value of 3.5 m for both sides of the road (corresponds to 1.75 m on either side).

Dialog Appearance, object type „Road“: additional width 3.5 m

Example

  • Enter on the dialog Road a road width of 3 meters and close the dialog with OK.

Road with a road width of 3 meters

The entered road width represents the distance of the emission lines (distance between the center lines of the outer lanes). The distance from the emission lines to the curb is half of the additional width entered on the dialog Options|Appearance „Road“. This holds for all other types to specify road width analogously.

Variable Road Width

When the road width changes in the course of the road, this can be taken into account in CadnaA for each road section. Assume, the road width changes from 3 to 5 m, then continues for two polygon points with constant width and then reduces to 2.5 m.

  • Enter a new road with at least 6 polygon points using the mouse.
  • Double-click on the road axis to open the dialog.
  • Enter for „SCS/Distance" a value of 3 m.
  • Drag the dialog Road aside to be able to see the entire road and then click on the button "Geometry".

Dialog Road: Geometry, entering a road widthof 5 m at the second polygon point

  • In the upper part of the dialog Road:Geometry the point list with the polygons x,y coordinates is shown. Enter into the second line in column "Dist (m)" a value of 5 m. The polygon point edited is blinking in the screen representation.
  • Enter the values for the road width at the further polygon points according to the following table:

  • Close the dialogs Road|Geometry and Road with OK.

Varying road with at polygon points

The edited road widths are retained for the subsequent polygon points as long as no other value is entered.

Variable Lateral Slope

A further table column „LSlope (%)“ on dialog Geometry enables to specify the lateral slope of the road. The lateral slope is acoustically only relevant when it alters the position of the emission lines considerably.

  • Open the dialog Road from the previous example and drag this aside again.
  • Open the dialog Road:Geometry.
  • Double-click into the first line of the point table. Subsequently, the dialog Road:Point is opened.
  • Move to the second polygon point by clicking once the right arrow key and enter there a lateral slope of 5%:

Lateral slope of +5% at the second polygon point

  • Move two polygon points downwards using the right arrow key and enter a lateral slope of -5%.
  • Close all three dialogs by OK.
  • Select from the road’s context menu the command 3D-Special.

On the 3D-Special view the lateral slope can be judged visually. Press the RETURN-key to move the camera along the road.

Road with lateral slope

The lateral slope is interpreted as a rotation around the road’s axis. A positive lateral slope increases the right curb when looking from first to last point, while a negative slope increases the left curb. An entered value applies to all following polygon points until a new value is entered.

Further instructions how to enter complex road geometries can be found in the CadnaA reference manual, see Common Input Data, Specification of Road Width.