The University of Twente carried out research into methods and measures for reducing and where possible improving the noise nuisance caused by traffic. This summer, UT researcher Marieke Bezemer-Krijnen obtained a doctoral degree within the context of this project, in which she researched the influence of the road surface on noise.
Porous asphalt is a successful measure for reducing traffic noise. A model method was developed for predicting the sound absorption of these porous roads. This model method can be used for developing new roads by optimising the sound absorption in the design stage. Using the results of the model method, two prototype roads were developed and constructed. Both roads were extensively tested. Both the sound absorption and the sound radiation were measured in combination with various tyres.
The model method can be used to predict both the sound absorption for perpendicular incident waves and the absorption for diagonal incident waves. The latter is an important characteristic if the model method is used as a design tool for optimising the sound absorption of porous roads. Traffic noise caused by diagonal incident will then be reduced. This is relevant, as traffic noise is especially perceived at an angle.
Research by the WHO Regional Office for Europe has shown that every year, one million healthy life years are lost in Europe owing to road traffic noise: irritation (587,000 years), ringing ears (tinnitus, 22,000 years), cognitive damage in children (45,000 years), and heart attacks (61,000 years) are major problems. Above a speed of fifty km/h, traffic noise is dominated by tyre-road surface noise.
Marieke Bezemer-Krijnen worked as a PhD student in the department of Applied Mechanics. Her thesis supervisor was prof. A. de Boer of the Faculty of Engineering Technology (ET). The PhD thesis Sound absorption of porous structures - a design tool for road surfaces can be requested from the contact person below.