A New Method for Reliable Determination of the Acoustic Performance of Low-noise Road Surfaces at Speeds below 50 kph

Recently, the focus of noise abatement policies increasingly included secondary (collector) and tertiary (local) streets in inner-city environments where noise exceeds the limits. Even at streets with lower traffic speeds, low-noise road surfaces have become a popular and widely used measure to combat road traffic noise at its source. The noise reduction achieved by such surfaces is usually known for free flowing traffic conditions at speeds of 50 kph or higher. For reliable determination of the noise reduction potential by low-noise road surfaces in inner-city environments, an adequate traffic noise emission model (TNM) is needed. Since the emphasis of currently available TNMs was frequently laid on higher speeds, they mostly do not accurately represent road traffic noise at lower velocity ranges where driving behaviour and propulsion noise become increasingly important. In the framework of a Swiss national research project, based on an up-to-date vehicle fleet a new TNM for lower speeds was developed focussing on the main influencing parameters, such as driving behaviour, gear selection, driving style and acceleration/deceleration. The TNM allows for reliable prediction of the acoustic effect of low-noise road surfaces in inner-city environments at speeds below 50 kph.