Road Noise Calculations

SoundPLAN calculates simulations of road and parking lot noise. Data entry and calculations are made according to the requirements of the specific standard. Choose in the SoundPLAN Manager which standard you want to use.

The input parameters are slightly different for each standard. If you have specific questions about a standard, mail them to support@soundplan.com. Each standard in SoundPLAN was tested against hand calculated examples or "official" test questions. Not all standards have "official" test questions, which necessitated our using hand calcualted examples to ensure accuracy.

The calculation of road noise, in general, is split into an emission model and a propagation part. For the most part, the interface between the emission and the propagation calculation is the sound pressure level in a set reference distance. Because the reference distance is different for most standards, it is impossible to directly compare the emission values. It is also impossible to enter the data for one standard and then undertake the calculations using a different standard.

Right clicking a coordinate opens an additional menu with editing functions. "Edit object properties" opens a dialog box where the coordinates and the attributes are visible.

Clicking the "Edit object properties.." opens a list of attributes assigned to each coordinate. Use the controls to quickly move to the next object of the same type, to the next coordinate, to the next coordinate with attributes attached, or to the last coordinate.

Unique to SoundPLAN, a road spanning the entire study area can have multiple changes in speed, traffic volume, percentage of heavy vehicles, road surface, etc. and still be the same object. This makes SoundPLAN more flexible than any other noise model because other models require new objects wherever a parameter changes. SoundPLAN is not only more flexible with this object entry feature, but it is also more flexible because of its built-in spreadsheet capabilities. It is the only noise modeling software where you can get the noise level from the entire road without having to take multiple contributions into an external spreadsheet program to get the final numbers.

Attribute operations allow the parameters for multiple objects to be controlled with one function. Most parameters for most object types are open to this feature.

Most calculation standards require the answers use a particular descriptor such as the L_eq for day and night, or the L₁₀ for 1 hour and 18 hour periods. The EU noise mapping requires the answers use L_den, the L_eq for the time periods day, evening and night. Assuming traditional answers will be used for quite some time, SoundPLAN has the flexibility to create both answers. To do this, use SoundPLAN's traffic volume time histogram. Create 24 hour traffic flow templates that are typical for certain areas and have the program break down the average daily traffic into hourly flows that can be arranged to represent either the traditional descriptors or the  L_den for EU compliance. For further description of the EU-type noise calculations and the templates, please refer to MODULES/EU-NOISE MAPPING.

Road noise calculations are not always for typical roads as described in the standards. SoundPLAN has provisions for roads on bridges, roads in tunnels and roads with noise barriers that are angled and extend over the roadway. None of these cases are considered in any of the standards. However, SoundPLAN provides solutions for all of these situations. For example, lets look at the following bridge calcuation.

You define the bridge and SoundPLAN calculates the screening. The program will regard the screening from the bridge mainly for the sources on the bridge itself. Noise from roads underneath will pass through without being screened. For screens reaching over the roadway, there are extra provisions called the floating screen.

For dimensioning noise protection walls for roads, please see  Wall Design.

Last modification: 14 January  2004

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