Acustics

The localization of noise sources on vehicles and roads is the basis for the targeted development of noise reduction measures. For this purpose, modern metrological and conceptual analyses are applied in order to provide evidence of the effect, in addition to finding the cause and solving the problem.

In addition, noise emissions and immissions are assessed as a whole and, based on this assessment, noise protection concepts are developed for both the road and the vehicle. For these concepts, all relevant stakeholders and their interests are analyzed and recommendations for action and instruments for noise reduction are derived.

The limits of individual operating conditions are verified by measurements of vehicles on the track. For an appropriate noise abatement measure, frequency response analyses and intensity measurements of the sound sources are also required in order to apply attenuation and absorption according to their effective ranges. In this way, even older vehicles from the existing fleet can comply with the applicable limit values of the TSI Noise or the recommendations of the VDV publication 154 of the Association of German Transport Companies (VDV) at low cost.

Especially in commuter traffic, rail vehicles produce rumbling, hissing, and squealing noise in addition to rolling noise. Curve squeal is particularly unpleasant for residents due to its high volume and tonal content. By measuring the relevant structural parameters, the exact shape of the vibration can be determined and individual vehicle solutions can be developed to reduce or even eliminate curve squeal.

For acoustic acceptance measurements of vehicles, certain wheel and track conditions must be met. The surfaces at the wheel-rail contact point should be as smooth as possible and lie below a limit curve according to DIN EN ISO 3095:2014. The Chair of Rail Vehicles has a special measuring device to determine these parameters. Another condition is the track decay rate. Here, too, the frequency response must be determined by measurement and must not fall below the limit curves in the relevant acoustic frequency range.

Combined investigations of sound radiation using modern simulation and measurement methods and of structural vibrations (using experimental and numerical modal analysis) allow the localization of sources and transmission paths and the development of appropriate mitigation measures.