Skip to main content
European Commission logo print header

Train pass-by noise source characterization and separation tools for cost-effective vehicle certification

Periodic Reporting for period 1 - TRANSIT (Train pass-by noise source characterization and separation tools for cost-effective vehicle certification)

Reporting period: 2019-12-01 to 2021-05-31

Train designs should no longer have to compromise comfort for speed. Improving passenger ride comfort and reducing the environmental impact of railway vehicles is a priority, with noise control topping the list. However, certification and authorisation procedures are currently costly and time-consuming, while the application of complex materials to reduce vehicles' weight and fulfil energy efficiency needs affects noise insulation. The EU-funded TRANSIT project is a consortium of universities, research institutions and companies specialising in railway noise and vibration, aiming to provide the railway sector with instruments and methods that will reduce interior noise in vehicles, at the same time developing advanced methods that will facilitate virtual testing and lead to more economical vehicle certification and authorisation procedures. TRANSIT will create new methods and tools that will give a better understanding and quantification of the contribution of the different sources to the total train pass-by noise. These methods and tools will reduce the costs and efforts required for certification testing, greater comparability and reproducibility of test results and ultimately improved competitiveness for the EU rail industry and increased social acceptance of railways leading to modal shift.

TRANSIT aims at realizing a break-through in virtual testing and virtual certification by developing validated source characterization, exterior noise simulation models, and measurement-based separation techniques.
TRANSIT aims 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. To that end the TRANSIT consortium has formulated 5 high-level objectives.

Objective #1: Reduce rail vehicle noise certification lead time and costs, and lower operator’s track occupation requirement for testing by providing accurate virtual certification tools.
To improve the global noise modelling tool developed in ACOUTRAIN, TRANSIT will develop source characterization methods including installation effects such as shielding and diffraction. The main purpose is to develop and validate a simplified method, derived from ACOUTRAIN. These methods has been validated under controlled conditions.

Objective #2: Reduce the need for a TSI-compliant track by developing and demonstrating accurate separation and transposition techniques.
The state of the art in separation methods has been evaluated. Using requirements on desired accuracy and target costs, strategies for enhancing these separation methods (PBA-based, TWINS-based and ATPA-based) have been described. Due to the unavoidable postponement of the measurement campaigns, these separations methods have only been tested in ongoing numerical simulations. [WP3]

Objective #3: Derive a more precise and better-founded definition of acoustic requirements for equipment suppliers, reducing time and cost.
Equivalent models to describe source sound power and directivity and the corresponding measurement techniques are developed, based on existing standards (e.g. ISO 3744) as far as possible. The validation of the methods on railway acoustic forces is delayed due to COVID-19 and will take place in the second half of TRANSIT.[WP1]

Objective #4: Improve source quantification for noise mapping and a more accurate assessment of noise abatement measures.
The methods developed in WP2 and WP3 will have a direct application in obtaining sound power source terms for statutory prediction models for noise mapping or planning. Methods for pass-by source separation and track-vehicle separation are developed and evaluated based on synthetic and experimental data from previous projects, and numerical simulations when feasible. Due to the unavoidable postponement of the measurement campaigns, the experimental validation will take place in the second half of the project. [WP2&WP3]

Objective #5: Enable lighter vehicles, thus lower energy consumption, while maintaining high levels of interior acoustic comfort.
The feasibility of innovative new approaches to noise abatement and sound quality improvements have been reviewed. Focusing on noise control in HVAC systems, where micro-perforates, acoustic metamaterials and UTLF arrays have been reviewed. The UTLF resonator array has been modelled using Finite Element simulation tools and experimental validation is pending. To reach this objective, also various roof designs and horn cover designs have been reviewed. [WP4]
Within the first reporting period, relevant methods in the state of the art have been evaluated. These methods have been evaluated through tests in controlled conditions, numerical simulations and Finite Element simulations. These evaluations have been made in preparation of the measurement campaign which is planned for autumn 2021. Track versus vehicle separation and transposition techniques will be experimentally validated. After the measurement campaign, these methods and tools will be further developed such that these can be employed within the railway community. Additionally, the acoustic performance of air conditioning ducts and panel structures with innovative materials will be validated through measurements in close to realistic conditions. These methods and tools will contribute towards an decreased time and effort require for vehicle certification and authorisation through virtual testing. This will speed up the design of trains with improved passenger ride comfort, reduced interior noise and reduced environmental impact.
TRANSIT Logo