Abstract
Road transport has been the dominant source of noise in the environment for many years and most of the noise is nowadays generated by the interaction of the tyre with the road, beginning with relatively low speeds. The condition of the road wearing course is the factor that particularly influences the noise pollution generated by the movement of vehicles on roads. The CPX method (CloseProXimity) used for measuring the amount of noise from the rolling of tyres consists of drawing a special trailer fitted with reference test tyres that are surrounded by microphones recording the noise generated by the rolling tyres along a test section. This dynamic method allows the evaluation the noise from the road surface in the field for the full length of the examined road section. It can be performed during the normal operation of the road with no need for traffic restrictions. Monitoring and early exchange of road surface can significantly contribute to the sustainable development of transport and a reduction of its negative impacts on the environment and human health thanks to the effective reduction of the excessive noise from road traffic. This paper presents the process of field measuring tests with a subsequent evaluation of results.
Highlights
CPX METHODThe CPX method is described in detail in the draft standard ISO/CD 11819-2 - Acoustics – Method for measuring the influence of road surfaces on traffic noise – Part 2: The Close Proximity method, 2000
This paper discusses the dynamic method where the measurement consists of the assessment of noise emitted from the whole length of road on the basis of special reference tyres by CPX method
CDV within the projects “Change of noise from road surfaces over several years of use” (Křivánek et al, 2012) and “Transportation R&D Centre” further innovated, improved and optimized the trailer they designed for measurement with the CPX method – the only device in the CZ for noise measurement using the CPX method
Summary
The CPX method is described in detail in the draft standard ISO/CD 11819-2 - Acoustics – Method for measuring the influence of road surfaces on traffic noise – Part 2: The Close Proximity method, 2000. Measurements are performed with the intention to determine the noise produced at the tyre/road interface at one or more reference speeds – 40, 50, 80, and 100 km/h. The method gives a good estimate of the acoustic characteristics of road surfaces. It can be used to study the homogeneity of road surfaces over long distances and under different conditions, or monitor the road maintenance so as to assure its efficiency (Ongel et al, 2008; Paje et al, 2010). The advantage of assessing the tyre performance using this method is that the influence of other sources of noise, such as the engine noise and the noise from exhausts, is reduced to a minimum (Wong et al, 2009)
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