According to Future noise policy, European Commission Green Paper (DG XI, 1996) 20 per cent of the population in the EU is exposed to unacceptable traffic noise levels of more than 65dB(A) LAcq and another 45 per cent are exposed to annoying 1evels of more than 55 Db(A) LAeq. Nowadays the essential mechanisms of noise excitation of a vehicle are no longer the motor and the power train, but in the speed range 40 km/h to 120 km/h the tire/road noise. From 120 km/h on the wind noise is the main noise source. The I-INCE report Noise emissions of road vehicles effect of regulations recommended Noise emission from tires during normal driving must be substantially reduced. As long as this is not done, vehicle noise regulations are likely to be ineffective. Tire/road noise reductionss may be achieved by use of a regulation similar to the amendment to the EU tire directive, but the limits must be substantially reduced to have an effect. From a regulation standpoint this approach seems quite reasonable, but neither with regulations nor with measurements tire/road noise can be reduced. The approach for efficient societal benefit for rolling sound emissions has to be considered on a global basis where the main actors are the pavement, the vehicle and the tire. Traffic flow management and driver behavior need to be included in this global approach. The tire industry is devoted to traffic noise reduction. Traffic noise is perceived as too high, is claimed to be hazardous to health and a protection of environment from unwanted sound is needed for silent city quarters. Also the comfort for vehicle passengers is strongly influenced by noise. Interior vehicle noise distracts from traffic situation, promotes fatigue and deteriorates speech audibility. The most efficient way to change this is noise abatement at the source. The tire manufactures have been searching for many years for a construction, which fulfills the targets of the automotive industry and generates less noise. If the main focus of the tire design in on low noise it is nowadays possible to build tires which are only I dB louder than a blank tire. This can be reached mainly by tuning the tread pattern and by choosing proper compounds. A further reduction of tire excitation by tread pattern optimization can not be expected. Therefore the excitation by road needs to be addressed. The highest potential (at least -10dB(A)) for immediate reduction of rolling sound emissions is the use of advanced low noise road pavements and surfacing. But also the tire has to adapt to the excitation by the road. On a medium term a 2 dB(A) reduction for all tire widths seems feasible keeping the other performances well balanced but with the two following constraints: The growth of the SUV market world-wide will require special consideration for off-road tires. And the trend for higher section width tire will certainly need to reconsider the splitting of class C1e which is unlimited for the moment. A technological break through is required if a shift of more than 3dB(A) for all the tire categories is required. Of course the tire industry is devoted to help reducing the traffic noise in situations where the rolling tire/road noise is dominant (A). Only abstract (as above) is available from the conference proceedings. For the covering abstract of the conference see ITRD E212343.
Abstract