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Embankment

The object „Embankment“ traces back historically to the modeling of road noise (see, for example, RLS-90, RLS-1990). At this time, terrain models were not commonly used when modeling the sound propagation outdoors.

The embankment has the following properties:

  • In acoustical terms, the embankment represents a double barrier with parallel diffracting edges at the distance of the „Top Width“ (vertical spacing of the screen edges).
  • The entered polygon is the baseline of the embankment. A positive slope generates the embankment to the right of the baseline, a negative slope to the left of it.
  • The upper edge of the embankment above the reference plane is given by the parameter „relative Height“.
  • Specifying a height on the dialog Polygon: Geometry raises the baseline of the embankment by the value entered. In general, the relative height of the embankment is zero (meter).
  • The embankment acts as a shielding object only, not as a reflecting one.
Embankment in plan view (2D view) Sectional view of the embankment

For more information regarding the guideline-specific properties of the object „Embankment“, see Industry Tab, Road Tab, and Railroad Tab.

Embankment in 3D-view

Furthermore, the following properties of the embankment with respect to terrain modeling are relevant:

  • The slope shown in the 3D view is drawn starting from the baseline and serves to identify the object as type „embankment“.
  • This slope shown in the graphics does not represent terrain and, therefore, does not influence the ground attenuation. In case a terrain model is present in parallel, the resulting ground attenuation is just determined by the terrain shape generated from the terrain model.

Note

The embankment is - despite looking like a terrain formation in the 3D view - not considered with other terrain-shaping objects (such as height points and terrain contours) in the triangulation. In particular, the two screening edges are not triangulated to nearby terrain contours, i.e. forming a „gap-free“ terrain. This is not an error, but due to the fact that the embankment is not a terrain-shaping object.

Dialog options

Name, Memo-Window, ID, ObjectTree

see Dialog Options Name, ID, INFO, ObjectTree, Master in the manual "Introduction to CadnaA"

relative Height (above baseline)

This parameter defines the height of the embankment‘s upper edge.

Slope 1:

The slope of the embankment being positive is drawn to the right, looking from first to last point, while a negative value it will be drawn to the left.

Top Width (m)

The perpendicular distance of the two parallel screening edges of the double-barrier.

Button „Geometry“

The object is an open polygon and the object height entered on the dialog Polygon: Geometry refers to the embankment‘s baseline. In general, the relative height is zero (meter). Otherwise, all options on the dialog are available (see Line-like Objects).

Further Information

Parallel Object

The command Parallel Object from the context menu of a road enables to generate an embankment parallel to this road by specifying the distance (distance road axis - baseline, see Parallel Object in the manual „Introduction to CadnaA“).

Conversion into barrier

When converting embankments to barriers (e.g. after a barrier optimization) the height attribute HREL of the embankment is written automatically to the attribute HA of the barrier (see Convert to in the manual „Introduction to CadnaA“).

see also: chapter Automatically Optimize Noise Barriers