Ground Vibration, main achievements:
The concept and framework of the ground vibration prediction tool has been defined, based on the general framework recommended in ISO 14837-1:2005 and the empirical procedures recommended in the FRA/FTA guidelines. This expresses the vibration level in a building during a train passage as the product of source, propagation and receiver terms. In a first step, a prototype vibration prediction model was developed, including a simple Graphical User Interface. In a second step this ground vibration prediction tool was fully integrated within the existing noise mapping software IMMI developed by Wölfel. In particular, geographical data can be imported through an interface with a Geographic Information System. Well-documented numerical and experimental case histories were subsequently used for approval testing and validation.
The software also includes a database of vehicle, track, soil and building data coming either from experiments or from computations. A track independent vehicle indicator to identify ground borne noise friendly vehicle is also proposed.
The main achievements of the ground vibration work stream are the following:
• Calculation method developed according to methodologies recommended by international standards and guidelines.
• Software tool allowing fast computations which are needed for large scale vibration studies (e.g. urban scale).
• Coupling with noise impact study software (IMMI). Mapping of CNOSSOS-EU database (noise) on SILVARSTAR database (vibration) for combined noise and vibration evaluation on the same model.
• Interface to GIS program (e.g. Open Street Map) for input data definition. 2D/3D views for visualisation of results.
• Validation against state-of-the-art software tools and well-documented case histories.
• Flexible approach: integrated database. Possibility to use calculated or measured data for each step of the computation. Possibility for the user to enrich the database.
Auralisation and visualisation of railway noise, main achievements:
The newly developed SILVARSTAR Auralisation Tool computes the auralisation of a train pass-by based on selectable input parameters (train and track types, speed, environment, noise mitigation measured). Auralisation model extensions were developed with an improved description of rolling noise sources and acoustic propagation (ground reflections and noise barriers). Different test cases using a regional train were computed for demonstrations and for comparison to pass-by measurements.The auralisation model was implemented as software with a graphical user interface. A functional VR application was developed by Empa. All required features and scenario options were included in the VR application. The software tools were successfully tested in demonstrations and at international exhibitions.
The main achievement of the auralisation and visualisation work stream are the following:
• Available free software tools for auralisation and Virtual Reality, which can be downloaded on Empa’s website (www.empa.ch/web/silvarstar).
• Physics based sound synthesis.
• Demonstration of scenarios with combined noise mitigation measures.
