Noise is one of the most important environmental problems related to road traffic. During the last decades, the noise emitted by the engines and powertrains of vehicles was greatly reduced and tires became a clearly dominant noise source. The article describes the concept of low noise poroelastic road surfaces that are composed of mineral and rubber aggregate bound by polyurethane resin. Those surfaces have a porous structure and are much more flexible than standard asphalt or cement concrete pavements due to high content of rubber aggregate and elastic binder. Measurements performed in several European countries indicate that such surfaces decrease tire/road noise between 7 dB and 12 dB with respect to reference surfaces such as dense asphalt concrete or stone matrix asphalt. Furthermore, poroelastic road surfaces ascertain the rolling resistance of car tires, which is comparable to classic pavements. One of the unforeseen properties of the poroelastic road surfaces is their ability to decrease the risks related to car fires with fuel spills. The article presents the road and laboratory results of noise, rolling resistance, and fire tests performed on a few types of poroelastic road surfaces.

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Tyre/road noise is the dominant component of overall vehicle noise at medium and high speeds and for cars even at low speeds. Consequently, road traffic noise can be reduced with the proliferation of quieter tyres. One way to achieve this is to give the tyre noise label greater attention among tyre and transportation consumers. Hence, the STEER project has evaluated the relevance and performance of the noise part of the European tyre label, looking at how it works in practice, analyzing its uncertainties and suggesting how it can be improved. Its main finding is that the uncertainties in the measurement of noise level for the label are too high to be acceptable. This paper focusses on the solutions offered by STEER for an improved tyre label. With four main improvements, the overall uncertainty of the current procedure can be halved. A few possible future strategies to increase the market share of quieter tyres have been analyzed and their effects quantified. If the tyre noise label is improved and the market share of quieter tyres can be increased as project STEER proposes, area-wide reductions of up to 3 dB in road traffic noise emissions compared to the present situation are possible.

Road traffic noise measurements, such as the Statistical Pass-By method (SPB) described in ISO 11819-1, are pivotal in assessing this noise pollution problem. As temperature is a primary cause of uncertainty in tyre/road noise measurements, the SPB method results need to be temperature corrected. The ISO 11819-1 standard is currently being revised and will refer to ISO/DTS 13471-2:2021, also in the drafting stage, for a temperature-correction procedure that is not present in the current ISO 11819-1:1997 version. Compared to other methods, little research has evaluated the temperature influence using the SPB method. In this paper, 18 SPB measurements were performed at three locations, with dense asphalt concrete and SMA as the pavement type. In total, over 5700 vehicles were captured, covering the complete temperature range in ISO 11819-1. For passenger cars, a temperature coefficient of −0.103 dB/°C was obtained while no statistically significant proof was found that temperature influences the sound-pressure levels for heavy vehicles at the speeds in this study (45–65 km/h). In this speed range for heavy vehicles, not only the tyre/road noise is a significant source of pass-by vehicle noise but also the power unit noise, on which the temperature influence is more complicated. Additionally, the analysis of various temperatures (air, road and estimated tyre temperature) revealed that the air temperature appears to be best suited for the temperature correction procedure. In third-octave bands, no effect was observed in the low-frequency range for passenger cars, contradicting previous research. Negative correction coefficients were found in the middle and high-frequency range, although trends presented in other studies were not observed.

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