Despite their known positive effects on road safety, the usage of rumble strips (audio-tactile profiled markings) in residential areas is currently problematic due to the noise that is radiated into the surroundings.
The aim of the project is to reduce the annoyance in the vicinity of rumble strips without causing a significant reduction of the warning effect for the driver. Three concepts will be studied and optimized.
The first concept is to apply cone-shaped gaps in order to direct the sound more towards under the vehicle. The second approach is a quasi-random variation of the inter-gap space. The aim is to produce a more random, noisy Signal instead of a tonal signal. The third concept is a sinusoidal rumble strip that mainly produces vibration and decreased radiation, mainly of low frequency sound. In this case the awareness of the driver is mainly caused by vibrations in the car. Such strips are for instance sometimes used in the USA.
The project starts with measurements on a test track with several different rumble Strip patterns using a passenger car and a truck. The vibrations and the noise inside the car as well as the noise in the surroundings are measured. Besides the calculation of spectra, psychoacoustic parameters will be evaluated. The vibrations are evaluated using the German kB method and the frequency weighted acceleration. Acoustic emissions are evaluated by means of psychoacoustic parameters and psychoacoustic tests in the laboratory. The results of the measurement are used to calibrate a numerical model for the wheel pavement contact.
The calibrated numerical model will be used to optimize the rumble strips with regard to the warning effect and noise emission. Subsequently, two types of optimized rumble strips shall be tested in praxis. Measurements and analysis of acoustic, psychoacoustic and vibration parameters will be carried out for these two milling patterns as for the initial test track in order to verify the optimization process.