The overall goal of TRANSIT is to provide the railway community with a proven set of innovative tools and methodologies to reduce the environmental impact and improve interior acoustic comfort of railway vehicles.
The associated high level objectives are:
- Reduce rail vehicle noise certification lead time and costs, and lower operator’s track occupation requirement for testing by providing accurate virtual certification tools,
- Reduce the need for a TSI-compliant track by developing and demonstrating accurate separation and transposition techniques,
- Derive a more precise and better-founded definition of acoustic requirements for equipment suppliers, reducing time and cost,
- Improve source quantification for noise mapping and a more accurate assessment of noise abatement measures,
- Enable lighter vehicles, thus lower energy consumption, while maintaining high levels of interior acoustic comfort.
In order to fulfil the high level objectives, the following
scientific and technical objectives are addressed:
1) Source characterization method independent of installation conditions.
TRANSIT will improve simulation capabilities for exterior train noise at standstill and pass-by according to ISO 3095:2013 [7] by building on existing tools developed in the previous project Acoutrain. Methods will be proposed and validated for source characterization based on sets of equivalent point sources (monopoles) including models for transmission paths, improving the methodology from Acoutrain. The transmission path models will include acoustic installation effects such as shielding and diffraction. A methodology will be proposed to estimate uncertainties of a complete simulation process.
2) Pass-by noise source separation methods
Novel and innovative techniques will be developed, in combination with existing methodologies with a proven track record, to determine the sound power level and directivity of the different types of noise sources during pass by at a constant speed. This will include aerodynamic sources, traction sources and rolling noise. The sound power and directivity of each source will be obtained in one-third octave bands, including an uncertainty assessment.
3) Separating the contributions of vehicle and track to the pass-by noise
TRANSIT will develop and validate methods for separating the contributions of vehicle and track to rolling noise during train pass-by, building on a number of promising techniques that were identified in the Roll2Rail project. These will be further simplified and/or enhanced here in order to improve their accuracy while also reducing cost. The methods will be able to transpose pass-by data measured on one track to another track. Wheel and rail roughness will also be separated. The validation and data collection will be extended to several vehicle scenarios using field measurements.
4) Investigate innovative materials and methods for an improved sound comfort
New and innovative approaches will be used to improve the design of the interior acoustics of future rolling stock. Several possible approaches will be considered, including optimal sound absorption at the source, damping along ducts for air conditioning systems and innovative meta-structure designs for the car-body parts.