Common Input Data

Name, Memo-Window, ID, ObjectTree, Master

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

Specification of Road Width

When clicking the file selector symbol to the right of the input box „SCS/Dist. (m)“ in the dialog Road the dialog Road Width is displayed enabling to enter, either the distance of the center lines of the outer lanes (location of the noise sources), or the total width of the road from curb to curb (in m). Alternatively, the predefined cross sections can be selected. Roads having a road width > 0 m have two lanes whole roads with a road width = 0 m will have a single lane only.

Distance of the outer lanes

The road width represented on the screen corresponds to the entered width only in case the additional width (at the curb) is set to 0 m (see below, Display real Width of Roads). In this case, the borders of the object „Road“ represent the centre lines of the outer lanes (noise sources).

Total width of road from curb to curb

The road width displayed on screen does not correspond to the entered width because a default distance of 1.75 m is presumed between the centre lines of the outer lanes to the curb. Therefore, a road with a total width of e.g. 10 m from curb to curb has a distance of 10 - (2*1,75) = 6,5 m between the centre lines of the outer lanes.

Display real Width of Roads

On Options|Appearance menu the additional width between the emission lines and the curb can be defined globally (object type „Road“). The value entered represents the sum of the curb’s distance left/right. Mark the object „Road“, select the first type of layer „Simple“, and enter the required additional width.

Appearance dialog for object type „Road“: additional width for distance to curb

Via the second type of layer „Simple“ the appearance of the centre lines of the outer lanes (sound source locations) can be defined. The settings concern all roads globally.

Appearance dialog for object type „Road“: for sound source appearance

Note

The centre line of the object „Road“ will always be displayed as a centre line, irrespective whether the real road has a single or several lanes in each direction (e.g. highway).

Road with additional width: emission lines and curbs

Standard Cross Section (SCS)

The standardized cross sections can be selected from the list with the mouse and clicking OK. The standardized cross sections result from the following German standards:

• Richtlinien für die Anlage von Straßen RAS, Teil: Querschnitte RAS-Q, Ausgabe 1982 RAS-1982 und 1996 RAS-1996, Forschungsgesellschaft für Straßen- und Verkehrswesen, Arbeitsgruppe Straßenentwurf, Köln.
• Entwurfshinweise für planfreie Knotenpunkte an Straßen der Kategoriengruppe B, RAS-K-2-B, Ausgabe 1995 RAS-1995.
• Aktuelle Hinweise zur Gestaltung planfreier Knotenpunkte außerhalb bebauter Gebiete, AH-RAL-K-2, Ausgabe 1993 RAL-1993.

Examples for Roads

In the subsequent section some examples are given for the input of roads.

Example 1: Single Lane Road

For a single-lane road, enter 0 in the input box „Standard Cross Section/Distance“ on the dialog Road or, if 0 is displayed as the default value, leave it unchanged. In this case just a single emission line exists.

Example 2: Multi-lane Road

For a multi-lane road, enter either the distance between the centre lines of the outer lanes, or select the appropriate predefined cross section. For example, when selecting the standard cross section „a6ms“ according to RAS-Q 82 RAS-1982, a distance of 24.75 m results between the centre lines of the two outer lanes. This corresponds to the road width displayed on the screen (with an additional width of 0 m).

Example 3: Road widening from 1 to 2 Lanes

In order to alter the distance of the outer lanes or the lateral slope along a road, each polygon point is edited individually via the dialog Geometry (see Object’s Geometry). Proceed as follows.

• Open the dialog of the respective road.
• Click the button „Geometry“ and double-click into a row of the geometry list.

Dialog Road: Point

• On the dialog Road: Point, enter the appropriate values for the distance between the axis’ of the outer lanes.
• Access the next or previous polygon point via the arrow buttons.

Via the button „New“ a new point is inserted. The road’s polygon point being edited is flashing on the screen. In order to see this, the dialog box may have to be moved apart. To keep the road width constant in the direction of geometry, it does not require to edit every polygon as the entered distance is kept until it is changed at a further point.

Widening of a road from 1 to 2 lanes

Example 4: Crossing with continuous lanes

The next example shows a crossing with continuous lanes.

In CadnaA, just enter the two intersecting roads. In case the traffic densities of the four combining road sections are different, it needs to model this road crossing from four road sections joining in the middle of the crossing.

Note

Regarding the use of traffic lights see Crossing.

Even when two road sections each are supposed to join in the middle of the crossing, the straight through-lanes are entered first and can be split afterwards.

Splitting of Roads into Sections

Option 1: Open the context menu by clicking on the centre line of the road with the right mouse button. Selecting the command Break Lines from the context menu splits the crossing roads right in the middle. This can be checked by clicking on the split road selecting just a half of it. Subsequently, by clicking one of the split road sections, select the command Break Lines once again, the non-split road will be split.

Note

Deactivate other objects - if any - being intersected by the roads in order not to be split as well.

If this is the case, and the other objects shall not to be split, proceed as follows.

Option 2: Instead of using the crossing roads as intersection lines for splitting, draw an auxiliary line - for example, a line source or an auxiliary polygon - on top of the centre line of the road to be split, and apply the command Break Lines from the context menu of this auxiliary line in order to split the road. Then, delete the auxiliary line. After splitting of the roads, different parameters such as traffic densities can be defined for the individual road sections.

for further options see the manual „Introduction to CadnaA“.

Example 5: Crossing with Filter Lane

This example is a combination of the scenarios already dealt with. At the transitions from the two-lane roads to the crossing and within the area of the crossing, the lanes are modeled from roads with a road width of zero. These are followed by two-lane roads in all four directions.

Any other geometry may be derived from those examples.

Lateral Slope

On the dialog Road: Point, the lateral slope can be defined - besides the outer lanes’ distance - from point to point (via button „Geometry“ of the road).

The lateral slope refers to the outer lanes’ axis which is rotated around the road’s centre line. A positive value lifts the outer right lane, a negative value the outer left lane. „Right“ and „left“ refer to the initial point when looking towards the final point.

Note

The entered slope holds also for all subsequent points into the direction of geometry. A new value needs to be entered only when the lateral slope changes again at a further point. Starting from this point, this new value holds again for all subsequent points.

Emission in dB(A)

The sound emission of a road is characterized by an emission level which is usually specific to the standard or guideline applied. This value is either entered directly or derived from road specific parameters for the selected road standard or guideline (see subsequent chapters specific to each standard/guideline).

Traffic Density

Counts, MDTD

Average daily traffic density (normally: vehicles per 24 hours): This is the number of vehicles passing a section of the road per day, averaged over the entire year.

Road Type

With the option „Counts“ selected, this list box enables to select the road type according to the selected standard. Based on this classification, default values for the hourly traffic density and for the proportion of trucks are used.

The road types specific to the selected road noise standard can also be assigned using the attributes STRGATT or STRGATT_NR. For details, see the chapter for each road noise standards below.

Diurnal Pattern

Further, the emission of a road can be described by a diurnal pattern containing hourly traffic data. Diurnal patterns can be defined in the global or in the local library (see Diurnal Patterns). After having defined a diurnal pattern in the global or local library its ID can be selected from the list box „Road Type“.

Diurnal Pattern PATT_01 selected on list box „Road Type“

Note

User-defined diurnal patterns can be assigned by using the attribute STRGATT (thus not by the attribute STRGATT_NR).

Exact Count Data

When the option „Precise Counts“ is activated, the relevant hourly traffic density M (in vehicles/hour) for the periods Day|Evening|Night and the mean proportion of trucks p% can be entered (vehicles with a gross mass > 2800 kg as percentage of the relevant traffic density).

Speed Limit (km/h)

This is the maximum speed, in km/h, permissible on the relevant road section for autos and trucks. This speed is taken into account according to the selected standard for autos and trucks. The default value for trucks is the same for cars. In case a different speed limit applies for trucks, activate the check box „Truck“ and enter the speed limit for trucks.

Note

Information on the minimum and maximum speeds for each road noise standard is given in the subsequent chapters.

Button DEN

When clicking the symbol speed limits can be entered separately for autos and trucks and for the time periods Day|Evening|Night.

Road Gradient (%)

The road gradient in % can either be entered by the user or calculated automatically, respecting the individual height profile of the road. The available options are selectable from the list box „Road Gradient“.

Dialog Road with list box „Road Gradient“

Road Gradient auto

With selection of „Road Gradient: auto“ the gradient of roads made of several road sections is calculated automatically. In this case, the displayed emission value (e.g. L_m,E with RLS-90) does not consider any gradient correction (also, not the tabulated emission value on menu Tables|Sources|Road). The gradient correction, however, is calculated for each road section automatically and considered within the calculation of propagation.

Select from the list box „Road Gradient“ into which direction the traffic flows on the two outer lanes. The arrows (or the abbreviations VA, AV, AA and VV) designate the traffic direction on the outer lanes, as seen from the first to the last point of the road (see figure below).

Road geometry and traffic directions

The letter „A“ and „V“ can be understood as arrowheads. For example, in case of traffic direction VA the traffic flow is - seen from the first point of the road - on the left outer lane into the opposite direction of the geometry points and on the right outer lane into the direction of the geometry points.

Note

The type of road gradient can also be specified by using the attributes STEIG and STEIG_AUTO (see CadnaA-manual „Attributes, Variables, and Keywords“).

Calculate Road Gradient

When selecting the command Calc Gradient of Roads from the Extras menu, CadnaA calculates the average gradient in % for all active roads based on their z-coordinates and the digital terrain model. The result is displayed and used as road gradient.

Note

Because the value applies for the entire road, the gradient is calculated from the height difference of the first and the last point of the road’s entire length. Otherwise, the road has prior to be broken into pieces (by the command Break into Pieces, with the option „Split at Polygon Points“) before calculating the gradient.

The gradient calculation using the command Extras|Calc Gradient of Roads occurs for all active roads simultaneously. In case this is not intended, deactivate those roads which are to be excluded from the gradient’s calculation and reactivate them afterwards.

Dialog Geometry

Source Height

The height entered in the dialog Geometry is the surface height of the road. Depending on the selected standard for road noise the source height (e.g. 0.5 m with RLS-90) is added for calculation. Thus, the road’s z coordinate is always the surface height.

Self-Screening

When the option „Self-Screening“ on the dialog Geometry is activated the road is just radiating into the upper half sphere. For the lower half sphere a screening effect occurs for all receivers below the road surface. This feature enables to define inclined roads, either upwards or downwards, by allocating the height above (relative) ground or an absolute height to every point of the road, and by defining an additional width (e.g. considering sidewalks etc.). Since the option „Self-Screening“ is available, the use of the object „Bridge“ became superfluous (see Bridge).

When selecting a predefined cross-section the respective additional width referring to the entire road profile is copied to the input boxes "Additional Width". This feature facilitates the consideration of ground absorption for the entire road width (see Ground Absorption Tab).

When calculating the screening effect at a road with self-screening option enabled, no projection occurs even if the corresponding option is activated (see Partition Tab). This must be considered when comparing results of situations with and without self-screening option enabled (in the latter case using a distinct barrier object).

level road with parallel barrier object, with projection

level road with self-screening active, no projection occurs (even with option ON on „Partition“ tab

Additional Width left/right

By default, the road width as displayed by CadnaA results from the sum of the width between axis of the outer lanes and the additional width as defined on dialog Options|Appearance (see also Specification of Road Width, default value: 3.5 m).

With the self screening-option activated, the actual road width can be specified by entering an additional width > 0 m. The additional width can be defined separately for either side of a road. A specified additional width overwrites the additional width defined on dialog Options|Appearance. These additional width is also displayed in the plan view and on the 3D-special view.

Height of Parapet left/right

In addition, parapets (e.g. parallel barriers) for the self-screening road can be defined, either on one or both sides by entering a height left/right > 0 m. The parapets are treated as fully absorbing on either sides. This characteristic cannot be changed. Absorbing or reflecting barriers without or with cantilever can be defined just by using the object „Barrier“ (see Barrier).

The following requirements and properties are to be respected:

• In any case, the additional width has to be > 0 m.
• The screens defined via option „Self-Screening“ are a characteristic of the road and are not displayed in the 2D-graphics, but just on the 3D-Special view (see 3D-Special View).
• Barriers defined via option „Self-Screening“ will screen just the own source (road), but not the noise from other kinds of sources.
• When calculating the effect by self-screening, in general no projection is considered, even if the corresponding option is active (see Partition Tab).

Station from/up to

This option enables to restrict the length of the barrier along the road’s axis with reference to the stationing. In this case, the barrier is just generated for the range „from-up to“.

This option is particularly useful when modeling bridges in order to suppress the diffraction around the edge of the road sections (road width) at bridgeheads.

For the automatic assignment two attributes are available:

• station start: SSCR_ST_B
• station end: SSCR_ST_E

Only for Ground Absorption, no Screening

With this option being activated, the additional width entered will not cause any screening effect, but will just be considered when calculating ground absorption. This requires, however, that the respective option on the configurations is checked (dialog Calculation|Configuration, tab „Ground Absorption“, option „Roads/Parking Lots are reflecting G=0“, see Ground Absorption Tab). With this option activated the speed of calculation may increase considerably due to the omission of barrier calculation.

The self-screening effect of the road’s surface - including parallel barriers, if any - just refers to the respective road itself. Thus, the parallel barriers (parapets) defined via „Self-Screening“ are not seen by other sources.

Additional information

The height of the road source above the road‘s surface depends on the selected road noise standard. The height on the dialog Geometry of the object "Road" refers to the road surface.