Road Noise Propagation, SoundPLAN

Road Noise Propagation, SoundPLAN

SoundPLAN modules Description

(Last Updated On: April 25, 2015)

Road Noise Propagation, SoundPLAN

The road module consist of 2 main parts; the emission calculation and the propagation calculation.

The emission calculation is always performed inside the Geo-Database where the vehicle numbers for various vehicle categories, the speed of the vehicles, and the road surfaces are fed into a calculation that results in the emission level. The emission level can be the sound power or a sound pressure level in a given reference distance from the road. Emissions are calculated for every section of the road. Where conditions change in traffic speed, volume or surface type, a new emission value is computed.

The propagation calculation is executed inside the Calculation Core. Calculations can be performed for single receivers or various types of noise maps (Grid Noise Map, Fa├žade Noise Map, Triangulated Noise Map, Horizontal Noise Map). The results from the calculations can be documented in the Documentation, Spreadsheet and in the Graphics. See these topics for details.

Road Noise propagation SoundPLAN

Road Noise propagation SoundPLAN

Road noise calculations in the city with the indication from where the noise was received. Red rays indicate reflected noise. Click on the diagram to start a movie sequence.
Road standards available in SoundPLAN

SoundPLAN is a standards based software system offering road noise calculations in accordance to all known international standards:

France / Europe: NMPB 96
Germany: RLS-90, DIN18005, VBUS
Austria: RVS 3.02
UK: CoRTN, CoRTN with Lden adjustments
Nordic: Statens Planverk report #48, Nordic Traffic Prediction 1996,Nord 2000 road
Japan: ASJ RTN Model B 1998, ASJ RTN Model B 2003
USA: FHWA Stamina type, TNM*
Russia: Russian road (Baltic Technical University)
Swizerland: EMPA StL 86, StL 95, StL 97
Emission adjustments for the Hungarian roads
TNM is not tested or endorsed in any way by the US Department of Transport.

Roadnoise Module Map SoundPLAN

Roadnoise Module Map SoundPLAN

The Road Noise Module

Road noise is the most widespread noise problem- world wide! The SoundPLAN road noise module is split into 2 sections, first the emissions of the line source are evaluated and assigned to the road source objects in the Geo-Database. In a second step noise levels are calculated for stand alone receivers or as part of the Grid Noise Map, Facade Noise Map, Cross-Sectional Noise Map or the Meshed Noise Map.

To mitigate the noise, speed restrictions on the road, quiet road surface, harmonization of the traffic flow, concentration of the major flow on arterial roads and noise protection walls are available. The optimization of berms and noise protection walls is described in the module WallDesign.

You can select any of the standards on the left for your work but must understand that for road noise. the emissions are standard specific and it is not possible to enter the road for the German RLS 90 and then calculate the noise levels in accordance to the British CoRTN. Emission and propagation must be defined for the same standard!

Most of the calculation standards have chosen to assess the noise levels for the Leq, CoRTN is the exception here with the L10 (for the END there is a conversion to Leq). For Leq based calculations it is possible create comprehensive answers with road noise and the noise from railway and industry.

Road Noise Emission Calculation
From the number of vehicles, the speed and the road surface, the GeoDatabase calculates the emission of the road. This emission is assigned to the coordinate where it was defined and is valid until a new definition replaces it. The factors and formulas for the emission parameters are standard dependant and as we have well over 20 standards, we refer here to your copy of the standard. What you find there is also part of the emission calculation. Some standards have extra provisions for traffic lights while others have provisions for the change in vehicle speed for roads up the hill.

The emission can be for 24 hours of the day or for the 3 time slots day/evening/night or for day/night. Some “emissions” of roads are the sound power Lw, for other standards the emission (or basic noise level) is the sound pressure in a reference distance (10m, 15m, 25m) depending on the standard.

Road Emission Calculation SoundPLAN

Road Emission Calculation SoundPLAN

Roads with emission are saved by the GeoDatabase and processed by the calculation core.

Import Road Data
With the DXF import interface you can import the coordinates of a road but not the attributes. On the left is a sample import of many objects organized layer by layer. Select the layer to import, import the data into a temporary Geo-File and then convert the data into the object (here roads) that you want the data to represent.

The Shape file interface allows to import attributes in addition to the coordinates. When importing such a file for the first time the program will show the attributes in the Shape File and all possible attributes for this object in SoundPLAN and lets you choose what needs to go where. After importing the data for the first time, the program already knows the correspondence and the import is faster. (See Shape File Interface)

Import Road Data SoundPLAN

Import Road Data SoundPLAN

One Road, many data sources

Importing a road from an external source does not mean that with one import the optimal results are achieved in one sitting. The road that had all extra parameters such as road width, road surface and the traffic related parameters was imported from an ArcView Shape File. The spacing of the coordinates resulted in a relatively jagged road that actually might cause problems being at some coordinates too close to buildings.

Fortunately we were able to get better alignment data from another source but these data only had the coordinates but no attributes. To rectify the problem, we divided the existing road into smaller segments, invoked the function “adapt road” to get the correct shape of the road and then filtered out excessive coordinates.

Road Noise Sources SoundPLAN

Road Noise Sources optimization SoundPLAN

Road Noise Source optimization Result SoundPLAN

Road Noise Source optimization Result SoundPLAN

The SoundPLAN Geo-Database is a toolbox that helps the engineer load, merge and correct model data into a consistent, high quality noise model.

Bridges

Bridges are structures where the noise can pass underneath. The noise from traffic on the bridge itself is shielded by the edge of the bridge surface or the solid barrier on the side. These parameters are assigned to the road itself.

Road Noise propagation Bridges SoundPLAN

Road Noise propagation Bridges SoundPLAN

For big noise maps it can be tedious to find the bridges, so SoundPLAN has implemented an algorithm to automatically detect the bridges from the terrain information around it. Mark the roads you want to detect bridges on and start Geo-Tools/more elevation tools/bridge detection you can enter into a search to find bridges = anormalities in the terrain. The height of the bridge edge then is a bit of a manual adjustment.

Noise from Road Tunnels

On the left you see the same situation as was modeled with the terrain but instead of a deep cutting, a tunnel was planned. Tunnels acoustically cannot be ignored, they need to be modeled in a special way.

Unlike regular road noise where the emission is close to the road surface, noise from tunnels is emitted over the entire moth of the tunnel. Depending on the absorptive characteristic of the tunnel walls, the frequencies shift to the lower frequencies, and the noise is emitted with a directivity. All these factors are included in the SoundPLAN object for tunnels.

Road Noise Propagation Tunnels SoundPLAN

Road Noise Propagation Tunnels SoundPLAN

The middle picture on the left depicts the regions around the tunnel mouth where the noise levels will be higher than from a regular road (SoundPLAN difference map), below is a typical directivity plot from the tunnel mouth.

Noise barriers of many shapes

Noise barriers do not have to be vertical structures, they can have different forms. In SoundPLAN you can define the angle between the sections and how many there are, the barrier below has first a vertical element of 4 m, then 5 of 1 m with 15 degrees between them and then the flat part with 7 meters.

Road Noise propagation Noise Barriers

Road Noise propagation Noise Barriers

Complex Geometry: Floating Buildings

Now buildings and industrial buildings can act like floating screens with noise passing underneath. The requirement is to ensure the building has this attribute enabled: “Building floats above ground.” This also means you can now model stacked buildings with Facade Noise Maps – even for the part with a smaller footprint, as you can see to the left.

So

Road noise propagation complex buildings modelling SoundPLAN

Road noise propagation complex buildings modelling SoundPLAN

Some movies of Road Noise Propagation results by SoundPLAN

Hobart City Noise Map with SoundPLAN
3D Road Noise mapping with SoundPLAN