[Back]

E. Pucher, J. Litzka, J. Haberl, J. Girard, J. Ejsmont, J. Lelong, J. Hamet, U. Sandberg, H. Bendtsen, G. Watts et al.:
"Recommendations on specifications for tyre and vehicle requirements";
Report for EU Projekt SILVIA (Sustainable road surfaces for traffic noise control); 2004; 116 pages.

This document is submitted in fulfilment of Deliverable 07 of the SILVIA EU research project. The goal of this document is to examine the parameters of tyres, vehicles and driving conditions in order to demonstrate the potential to further the noise reductions achieved by low-noise surfaces through a systematic optimisation of the vehicle, tyre and road surface. This work has been carried out as part of work package 5: Integration of Low-Noise Pavements with Other Noise Abatement Measures. This report gives an overview of the general effects of various tyre and vehicle parameters, a brief review of the SILVIA database, and analyses of the influences of various tyre and vehicle parameters on traffic noise. These analyses are based on data present in the SILVIA database, supplemented with results from relevant literature. Based on these analyses recommendations have been made concerning guidelines for vehicle and tyre manufacturers and legislators as a way to improve the performance of low noise surfaces through optimising the vehicle and tyres.

Proposed stronger guidelines have been given for "quiet vehicles." Currently, the system to designate a "quiet vehicle" is fairly forgiving. In order to provide a stronger motivation to the consumer to purchase vehicles with improved noise performance, the requirements for designating a vehicle as a "quiet vehicle" should be more stringent. In this report it is proposed that:
. The vehicle should be tested with the tyres sold on the vehicle - each vehicle model should be tested for each set of tyres sold with it, and the vehicle noise rating should change accordingly if the tyres are changed prior to sale or at the time of sale.
. The rolling noise and the accelerated pass-by noise should be measured under real life conditions, i.e. road surfaces in common use instead on an ISO surface, which is only a test track and never used for public roads.
. The vehicle should show an improvement over the fleet average noise level from vehicles for the given model year of at least 3 dB(A).
. The vehicle testing should cover the range of typical driving conditions.
. When users change tyres, a tax incentive should be implemented encouraging them to use the quietest tyres.

Vehicle parameters were examined, in addition to driving conditions. The resulting recommendations included those listed below:
. Electronic slip control systems should be more widely adopted - reducing slip can lead to decreases of as much as 3 dB(A) for pass-by noise.
. Special regulations for alpine regions regarding speed and night driving, and introduction of 4-wheel drive systems, for example, for heavy vehicles, are potential means of reducing traffic noise in areas where substantial gradients occur.
. Improved power unit soundproofing on diesel engines can yield reductions in noise levels at low speeds.

Tyre parameters were also examined regarding their impact on traffic noise. Some recommendations of note resulting from the analyses of tyre parameters were as follows:
. Wider tyres should be required to meet the same noise level standards as narrow tyres for the same type of vehicle.
. Tyre material properties such as the hardness of the rubber and the thickness of the belts should be optimised for given size parameters of tyres - such an optimisation can lead to a noise reduction of as much as 2 dB(A).

By implementing these guidelines, the authors feel that the next generation of quiet vehicles would show a marked improvement in noise performance over the current fleet.