Rail Noise Propagation SoundPLAN

Rail Noise Propagation SoundPLAN

SoundPLAN modules Description

(Last Updated On: April 25, 2015)

Railway Simulations

The railway 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 rail 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 rail. Emissions are calculated for every section of the rail. 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.

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

Railway standards available in SoundPLAN

Europe: RMR 2002
Germany: Schall03, Transrapid, Din18005, VBUsch
Austria: ONR 305011
UK: Calculation of Railway traffic noise
Nordic: Kilde 130, Nordic Traffic Prediction 1996, Nord 2000 railway
Japan: Narrow-Gauge Railways based on ASJ
Russia: Russian railway (Baltic Technical University)
Swizerland: SEMIBEL
France: (NFS 31-133): 2007-02

Rail Noise Propagation Time-Level Histogram SoundPLAN

Rail Noise Propagation Time-Level Histogram SoundPLAN

Rail Noise Emission Calculation
As the calculation of the emission is standards dependent, this overview can only show one example, it is taken from the WINCITY project and features the German Schall03.

Train tracks seldom only have one type of trains, therefore the train emissions provide the possibility to enter different trains from a train setup which SoundPLAN is delivered with but is fully customizable.

For each train, the number of trains for a given time slot (day/night or day/evening/night) needs to be entered, the length of the train and other data come from the library but can be altered. For each of the trains the emission level is calculated for the Leq, the sum of all trains for each time slot is also listed.

The emission level for trains does not only depend on the train type and speed but also has additions for the type of ballast bed, the squeal in curves, multiple reflections, railroad level crossings and bridges.

In addition to the Leq, the Lmax can be calculated for trains but the noise assessment must have provisions for it (an extra time slot for Lmax) and you must select which train to use for the Lmax calculation.

Rail Noise Propagation Emission Calculation SoundPLAN

Rail Noise Propagation Emission Calculation SoundPLAN

One Railway, many Definitions

Railway objects are variant objects so new definitions can be entered at any coordinate along the track. For a bridge, a level crossing or ballast bed or curve squeal or a change in speed on the railway, you do not have to create a new object, simply click on the coordinate where the change occurs and enter a new definition which then will be valid until it is replaced by a new definition.

Rail Noise Propagation movie by SoundPLAN

Calculating the Lmax

As the train cannot be treated as a point source but is a moving line source of a defined length, the calculation of the Lmax is just doing this, it assumes a start position on the track and with the train speed and all the other parameters calculates the noise level for the receiver. After the calculation, the train moves to the next position that it would assume in 0.2 seconds. Here the next noise level calculation is carried out. This loop goes on until the train has reached the end of the line.

The calculation of the instant noise level is complicated because with the length of the train it is no possible to ignore the fact that the direct and the reflected noise components may arrive at the receiver at different times, thus the speed of sound matters.

The sound levels from the entire train pass by is collected in a table and the program searches for the maximum value. The data also can be stored and opened up from the SoundPLAN Graphics to present the Level-Time-Chart and also to create the Animated Noise Map.

Rail Noise Propagation calculating Lmax SoundPLAN

Rail Noise Propagation calculating Lmax SoundPLAN

Rail Noise Propagation, Results Where? What?

Aside from the customary Grid and Facade Noise Maps the SoundPLAN Result Tables offer more insight for Single Point Sound Receivers. On the left you can see the time/level chart of a train pass by, you can also get the “normal” level diagrams that show from which direction the direct noise and the reflected components were received.

In addition to the receiver information, a documentation of the tracks and the trains is available.

Rail Noise Propagation Result tables SoundPLAN

Rail Noise Propagation Result tables SoundPLAN