Noise Classification Road Pavements (Technical) (1)

European Commission Directorate-General Environment

Noise classification of road pavements Task 1: Technical background information Draft report

June 2006

Report no. 1

Issue no. 5

Date of issue 12/06/2006

Prepared G. Descornet / L. Goubert

Checked

Approved

DG-ENV_Noise_Classification_Road_Pavements_ Task 1 Report _05

G. Descornet – L. Goubert 2/58

Contents 1 INTRODUCTION................................................................................................................................3 2 TRAFFIC NOISE AND ROAD SURFACES ....................................................................................4

2.1 WHY ABATE TRAFFIC NOISE? ........................................................................................................4 2.2 AVAILABLE TOOLS FOR TRAFFIC NOISE ABATEMENT.....................................................................6 2.3 THE INFLUENCE OF THE ROAD SURFACE ........................................................................................8

3 LOW-NOISE ROAD SURFACES ...................................................................................................11 3.1 TEXTURE-OPTIMIZED ONLY.........................................................................................................11 3.2 POROUS SURFACES ......................................................................................................................13 3.3 ELASTIC SURFACES .....................................................................................................................15

4 MEASUREMENT METHODS AND STANDARDS .....................................................................18 4.1 INTRODUCTION............................................................................................................................18 4.2 NOISE MEASUREMENTS METHODS ...............................................................................................18

4.2.1 Controlled pass-by (CPB)......................................................................................................18 4.2.2 Statistical pass-by (SPB)........................................................................................................19 4.2.3 Close proximity (CPX)...........................................................................................................19 4.2.4 Comparison between noise measurement methods................................................................20

4.3 AUXILIARY MEASUREMENT METHODS ........................................................................................21 4.3.1 Surface texture.......................................................................................................................21 4.3.2 Sound absorption...................................................................................................................21 4.3.3 Mechanical impedance ..........................................................................................................22

4.4 STANDARDIZATION .....................................................................................................................22 4.4.1 Noise measurement methods..................................................................................................23 4.4.2 Auxiliary measurement methods ............................................................................................23

5 NOISE CLASSIFICATION OF ROAD PAVEMENTS.................................................................25 5.1 INTRODUCTION............................................................................................................................25 5.2 STATE-OF-THE-ART AT NATIONAL LEVEL....................................................................................25

5.2.1 Austria ...................................................................................................................................25 5.2.2 Belgium..................................................................................................................................26 5.2.3 France....................................................................................................................................27 5.2.4 Germany ................................................................................................................................28 5.2.5 Hungary .................................................................................................................................28 5.2.6 Italy........................................................................................................................................29 5.2.7 Japan .....................................................................................................................................30 5.2.8 The Netherlands.....................................................................................................................30 5.2.9 Slovenia .................................................................................................................................32 5.2.10 Spain .................................................................................................................................33 5.2.11 Switzerland........................................................................................................................34 5.2.12 United Kingdom................................................................................................................34 5.2.13 USA ...................................................................................................................................35 5.2.14 Nordic countries ...............................................................................................................35

5.3 EUROPEAN PROJECTS ..................................................................................................................37 5.3.1 Introduction ...........................................................................................................................37 5.3.2 HARMONOISE......................................................................................................................37 5.3.3 SILVIA ...................................................................................................................................39

5.4 DISCUSSION.................................................................................................................................41 6 CONCLUSIONS AND RECOMMENDATIONS ...........................................................................46 7 REFERENCES...................................................................................................................................49 8 SYMBOLS AND ACRONYMS........................................................................................................57



1 Introduction Recent estimates indicate that more than 30% of EU citizens are exposed to road traffic noise levels above that viewed acceptable by the World Health Organisation (WHO) and that about 10% of the population report severe sleep disturbance because of transport noise at night [116]. In addition to the general disruption of activities and quality of life, there are additional adverse health and financial effects. According to OECD [117], the threshold of annoyance is 55 dB(A) in terms of average traffic noise level outside and the threshold of unacceptability is only 10 dB(A) higher: 65 dB(A). Now, the difference in vehicle noise emission between a noisy and a silent road surface can be much more than 10 dB(A), which means that the road surface alone could make the difference between a comfortably quiet road and a disturbingly noisy road. Thanks to legislation and technological progress, the noise from cars has been reduced by 85% since 1970 and the noise from lorries by 90%. Despite that, no significant relief of the exposure to road traffic noise has been recorded over the years. The growth and spread of traffic have offset the technological improvements. Another important factor is the dominance of tyre noise above quite low speeds (50 km/h). Now, noise abatement is more effective by reducing the emission at the source. That is why the Green Paper of 1996 states that the next phase of action to reduce road traffic noise will address tyre noise and promote low noise surfaces through Community funding [65]. Directive 2001/43/EC [109] provides for the testing and limiting of tyre rolling noise levels, and for their phased reduction. Limits differentiate between vehicle type (cars, vans and trucks) and tyre width (5 classes), and will be enforced by including tyre rolling noise tests in European Community type-approval certificate requirements, which must be met for any new tyre being placed on the European market [108]. No such regulation exists yet for road surfacings. A major problem to be overcome is the fact that a road surfacing is not a ready-made product. Tests made on the components are of no use with respect to noise. The noise performance will be essentially determined by the resulting superficial characteristics, which in turn will highly depend on the conditions and circumstances of the mixing and laying processes. Therefore, classifying or labelling such a product requires specific procedures based on specific testing methods to be developed, validated and standardized before an harmonized classification system can be proposed at European level. The purpose of this report is to overview the progress made so far in that direction and to derive recommendations on the efforts that remain to be accomplished.



2 Traffic noise and road surfaces

2.1 Why abate traffic noise? According to the WHO [64], noise can have a wide variety of adverse effects on human health and/or well-being:

• Pain and hearing fatigue • Hearing impairment including tinnitus • Annoyance • Interferences with social behaviour (aggressiveness, protest and helplessness) • Sleep disturbances and all its consequences on a long and short basis • Cardiovascular effects • Hormonal responses (stress hormones) and their possible consequences on human

metabolism (nutrition) and immune system • Performance at work and/or school decrements

For the European Union alone (excluding the NMS’s), it has been estimated that 80 million people are exposed to noise levels which are considered to cause one or more of these adverse noise effects. 170 million more people live in so called grey areas, where the high noise levels are likely to cause serious annoyance [65]. The “general” annoyance effect is considered as the most important effect of environmental noise pollution, and therefore it is widely considered as the basic health effect which should be controlled in the general population [66]. Sleep disturbance is considered as the second important effect of noise on human well-being, but recent research [67] shows that cardiovascular effects cannot be omitted: noise appears to affect the prevalence of myocardial infarctions at 60 dB(A) and higher1. Environmental noise does not only affect human health and/or well-being, it is also expensive. Estimates of costs of noise range between 0.2 and 2 % of the gross domestic product [65]. This corresponds for the E.U. with a minimal cost of 12 billion € [66]. Different sources contribute to the excessive exposure of European citizens to noise, but transportation noise and in particular road traffic noise is by far predominant. Figure 1 shows the relative contribution of the main sources of noise, according to a study in the Flanders region in Belgium [68].

1 Lday = 60 dB(A) is considered as the “no observed adverse effect level” for myocardial infarctions



16

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neighboursindustryconstructionagricultureroad trafficair trafficrail trafficcommercial activitiesrecreational activities

Figure 1 - Relative contribution to nuisance by different sources of noise in Flanders

According to this study, 40 % of the people highly annoyed by noise are annoyed by traffic noise. Figure 2 shows the development of the relative contribution to nuisance of the different noise sources in The Netherlands [69]. It appears that road traffic noise is not only the most important source, but also that its contribution is increasing.

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road traf f ic rail traf f ic air traf f ic industry recreation neighbours

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Figure 2 - Development of the relative contribution of different noise sources to nuisance



2.2 Available tools for traffic noise abatement There are different means to reduce the traffic noise level at or in the dwellings. Available tools are:

• Legal measures This type of measures is possible on the European (European Product standards, the Tyre Noise Directive and the European Noise Directive), the Member State, the regional and the local level. Although they are necessary to incite stakeholders to do efforts to reduce noise, this type of measures has in general only effect after a long time. For an extensive review, see [119].

• Socio-economic measures This type of measures includes noise awareness rising, training and education, control and behaviour sanctions, economic stimulations and sanctions and eco-taxing. These types of measures are often introduced with another primary goal, e.g. air pollution reduction or traffic safety, but turn out to have a positive effect on traffic noise (see also [119]).

• Land use By taking into account the traffic noise aspect while designing new cities and roads, a lot of noise exposure and annoyance can be avoided in this in a rather cheap way. Unfortunately, the noise aspect has only recently been “discovered” by land use planners, hence in Europe a lot of historically grown black points - a densely populated area exposed to a high traffic noise level – have been inherited. This is especially the case for densely populated countries like Belgium and the Netherlands. For these existing black points other measures will be necessary.

• Source-oriented measures Several sources can be located in motor-driven vehicles and motorcycles. One has to distinguish between cars, vans, heavy vehicles and motorcycles. For each type of vehicle, the ranking of the sources may be different. Some examples of noise sources are:

o Tyre/road noise o Engine noise o Exhaust noise o Aerodynamical noise

This category of measures has relations with “legal measures” and “infrastructural measures” (tyre/road interaction, see further). For a further discussion, see also [119].

• Traffic management (see also [65]) One can reduce the noise of a road by influencing the speed and/or traffic flow. Speed reduction is one way to reduce the noise, but this tool has of course its limits. Another example of traffic management are measures which induce the traffic flow to become more fluent, e.g. by a clever tuning of the traffic lights, in order to avoid as much as possible stop-and-go traffic. An overview of traffic flow measures and their potential



noise reduction is given in Table 1 [70]. For an extensive review of possible traffic related measures, see [120].

Table 1 – Potential noise reduction of traffic flow measures

Traffic management measure Potential noise reduction (LAeq)

Traffic calming / Environmentally adapted through roads up to 4 dB(A)

30 km/h zone up to 2 dB(A)

Roundabouts up to 4 dB(A)

Round-top/circle-top road humps up to 2 dB(A)

• Infrastructural Measures

There are several infrastructural measures possible: a low noise road surface (which prevents tire/road noise to be generated), noise barriers and façade insulation (which both reduce noise propagation to the neighbours of the road. The three methods have their advantages and disadvantages (see Table 2).

Table 2- Comparison of three possible measures to abate road traffic noise

Low noise road surface Noise screens Façade insulation Acts on noise generation Acts on noise propagation Acts on noise propagation Moderate noise reduction (typically 3 up to 6 dB(A) for current generation of

low noise surfaces)

High noise reduction possible (typically 7 to 12

dB(A))

High noise reduction possible (typically 10 to 20

dB(A))

Not intrusive Intrusive Not intrusive Reduces noise in open air Reduces noise in open air,

but mainly at short distance of the source

Reduces noise indoor only and with windows closed

Relatively cheap Expensive (extra construction)

Generally most expensive solution

Medium lifetime Long lifetime possible Long lifetime Not vulnerable to

vandalism Often vulnerable to vandalism (graffiti)

Not vulnerable to vandalism

Maintenance required Maintenance required No maintenance required A tool to compare the effectiveness of different noise abatement measures was developed in the frame of the SILVIA-project [33].



2.3 The influence of the road surface The noise generated by the interaction of the tires and the road surface is for passenger cars nowadays the predominant noise source at very low speeds. This is due to the fact that other noise sources (like power train noise, exhaust noise …) have been efficiently dealt with by car manufacturers in the last decades. For “new” cars2, tire/road noise is already predominant at speeds between 15 and 35 km/h. For older cars, this limit lies between 30 and 50 km/h [35]. Tire/road noise is a complex addition of several mechanisms of noise generation and amplification, depending both on tire and road surface properties3:

• Noise is partly generated by impacts and shocks on the tire, caused by road surface irregularities or irregularities on the tire tread. These shocks make the tire vibrate and radiate noise. Vibrations of the tire tread spread to the sidewalls, which radiate noise on their turn.

• Aero dynamical noise sources include the so called air pumping, consisting of the noisy pushing away of air on the leading edge of the contact zone between tire and road surface and the noisy sucking of air on the rear edge. Also the resonances in the tire cavity and in tread pattern canals can be considered as aero dynamical noise sources.

• A micro movement effect is the stick/slip tread elements motions relative to the road surface, causing the tread elements to vibrate tangentially

• An adhesion effect is the stick/snap effect of the sudden loosening of the tire tread from the road surface, comparable to the sudden loosening of a suction cup.

• The horn effect is a noise amplification mechanism. Noise being generated near the edge of the tire/road surface contact area is reflected several times between the tire tread and the road surface, amplifying the noise in a certain direction. This is the same phenomenon which is wanted with the conical part of e.g. a trumpet or a megaphone.

A breakthrough of the understanding on the influence of the road surface on the noise generation and amplification came in the beginning of the 1980’s [73], when one found that coarse irregularities4 on the road surface are a negative factor as they induce tire vibrations. Fine irregularities5 on the other hand were found to have a favourable influence on the noise generation, as they prevent air pumping. Before the air can be trapped and compressed in the tread pattern and consequently escape in a noisy way, the fine texture allows it to flow away silently between the fine horizontal channels formed by the tire tread and the irregularities. Fine texture is not necessary in the case of porous surfaces, as in this case air can flow away vertically through the pores before it is

2 cars built later after 1996 3 for extensive reviews, see e.g. [35, 71, 72] 4 with horizontal dimensions (“texture wavelength”) of a approximately 1 cm up to a few tens of cm, the worst being irregularities with horizontal dimensions of about 8 cm, corresponding to the dimensions of the tire/road contact zone. This unfavorable irregularities belong to the so called megatexture region (5 cm up to 50 cm) and partially also to the macrotexture region (0,5 up to 5 cm). For definitions see [78]. 5 With horizontal dimensions of typically 2-3 mm, also belonging to the macrotexture range.



compressed. Porous surfaces can be made to absorb sound by a proper design, including a high content of interconnecting voids, a sufficient layer thickness and a flow resistance which is not too high. The basic requirements for a low noise road surface may be summarized in the following rules of thumb [35]:

• For dense wearing courses o Minimal megatexture and minimal macrotexture in the texture wavelength

10 – 50 mm o Maximal macrotexture in the wavelength 1 – 8 mm

• For porous road surfaces o Minimal megatexture and minimal macrotexture in the texture wavelength

10 – 50 mm o Void content of at least 10 % by volume, preferably higher o Porous layer thickness of 40 mm or higher o Flow resistance of 20 to 50 kNsm-4 for high speed roads and 12-30 kNsm-

4 for low speed roads Since the 1980’s, several solutions have been developed to approximate these requirements in practice, taking into account also other requirements like skidding resistance and durability. Very fine texture (microtexture) also has some influence on the tire/road noise [35], which is however not yet studied in a quantitative way, due to the lack of proper measurement techniques to quantify microtexure. Besides texture and noise absorption, a third basic parameter of the road surface influences the tire/road noise generation, namely its stiffness, also called “mechanical impedance”. It is showed that if the stiffness of the road surface is of the same order of magnitude as the tire, huge noise reductions can be obtained (in the order of 10 up to 12 dB(A)). As low noise road surfaces with texture and noise absorption which does approximate the “ideal” situation quite well, mechanical impedance is currently the only parameter with which large additional tire/road noise reductions may be obtained in practice. Water on the road surface may significantly influence the tire/road noise, but only approximate corrections factors exist. No studies are available in which the amount of water on the surface has been quantified. The corrections factors [75] for dense asphalt concrete (DAC) and Stone Mastic Asphalt (SMA) road surfaces are given in Table 2. On porous surfaces, no significant increase of tire/road noise has been found [76], which can be considered as important advantage for this type of road surface in rainy climates.



Table 3 -Correction factors for humidity on DAC and SMA-surfaces

Amount of water on road surface 0-60 km/h 61-80 km/h 81-130 km/h dry reference reference reference

humid (drizzle) + 2 dB(A) + 1 dB(A) + 0 dB(A) wet (moderate rainfall) + 4 dB(A) + 3 dB(A) + 2 dB(A)

wet (heavy rainfall) + 6 dB(A) + 4 dB(A) + 3 dB(A)

Temperature has also an influence on the tire/road noise generation, depending on the tire and the road surface texture. Generally, the tires become less noisy the higher their temperature, due to the weakening of the rubber, making noise radiation by tire vibration less efficient. The effect is typical -0,05 up to -0,10 dB(A)/°C on the result of a noisiness measurement of the statistical pass-by level. A table with state-of-the-art correction factors is given in reference [77].



3 Low-noise road surfaces This chapter describes the practical realizations of low-noise road surfaces.

3.1 Texture-optimized only

• Resin-bound surface dressing Definition: a high performance surface dressing which consists of a layer of resinous binder densely spread with high PSV6, small size aggregates (e.g. 2/4 calcined bauxite) [78]. As chippings, crushed natural rock as well as an artificial aggregate (e.g. milled steel slag) can be used. An example is the so called Italgrip, consisting of milled steel slag aggregates (1-4 mm) bound in a layer of epoxy resin [81]. Properties: This surface type is durable and has a high, durable skidding resistance, which makes it especially suitable for use in bends, highway exits etc. The surface is very quiet, due to the smoothening of the megatexture by the initially very liquid resin and the good fine macrotexture of the closely packed fine array of small stones. A disadvantage is that it is quite expensive. History: After the discovery of the surface characteristics which influence tire/road noise generation in the second half of the ‘70ties, some experiments [79] were conducted in Belgium with surface treatment techniques in order to approximate the “ideal” texture. A surface dressing with 1-3 mm chippings bound with a polyurethane binder gave after two years of operation a noise reduction of 3-4 dB(A). A similar surface dressing was later applied in Austria, in order to reduce the rolling noise on noisy cement concrete surfaces [80]. • Exposed aggregates cement concrete

Definition: this type of cement concrete undergoes a special treatment immediately after the construction: the still wet cement concrete is sprayed with a retarding agent and covered with a tin foil. After one up to two days, the foil is removed and the upper layer (of a few mm) of cement, which is not hardened, is removed with brushes or water under pressure. Properties: very durable surface with reasonable acoustical properties, if the following conditions are satisfied:

o Smoothening of the wet surface must be done by means of a longitudinal smoother (not by a traditional transversal one which often induces waves in the megatexture range in the surface)

o Appropriate aggregate grading must be used in order to obtain a closely packed array of small stones at the surface.

6 Polished Stone Value



Optimized exposed aggregate cement concrete my yield a reduction of up to 3 dB(A) with respect to the reference surface, a dense asphalt concrete with 11 to 16 aggregates. Because it is not easy to design a cement mixture which is at the same time strong and texture optimized, one sometimes applies two layers. The under layer being strength optimized and the upper layer texture optimized. More expensive aggregates may in that case used for the upper layer without making the surface extremely expensive. History: This type of surface has been applied since the beginning of the 1990’s in Austria [82], Belgium [83] and the Netherlands [84]. Especially in the Netherlands, research was done afterwards about the optimization of this road surface type [85]. • Ground cement concrete

Definition: the grinding of a concrete surface is done by means of set of closely spaced diamond disks, forming thin (typically 3 mm wide) parallel, longitudinal grooves. The closed packing leaves the edges between the grooves smooth, as most of the peaks split in the process. Properties: This is an attractive way to reduce the noise of an existing cement concrete road with a lot of megatexture, but which is still in a technically good condition. A ground cement concrete surface is generally much less noisy than cement concrete before the grinding (about 5 dB(A) [78]), and its noisiness may be of the same order of a reference dense asphalt concrete surface. Hence it is not really a low noise surface in the sense of the definition given in the beginning of this chapter. The new texture may last for about ten years, provided it is not in a region or country where studded tires are used in winter times, where the lifetime is only one to two years. After the wearing away of the texture, it may be ground again. This cycle may be repeated three or four times [87]. A disadvantage is the relatively high cost (about 1 €/m²/mm depth) [78]. History: Grinding of cement concrete was done for the first time in California in 1965 and has been done a lot in the USA and occasionally in Europe [35].

• Thin layers

Definition: A thin layer can be defined as an integrated, independently functioning wearing course consisting of a warmly produced bituminous mixture, excluding mastic asphalt [88]. It is in fact a set of different types of surfacings and includes three subcategories:

o Very thin surfacings: thickness between 20 and 30 mm (definition according to [90])

o Ultra thin surfacings: thickness between 12 and 18 mm (as defined in [35]) o Micro surfacings: thickness between 6 and 12 mm (as defined in [35])



Sometimes a broader definition is used [78], also including coldly produced bituminous mixtures and surfacings on resinous basis (which were discussed above). To the very thin surfacings belong:

o SMA-type layers (open-graded but semi-dense) o Porous layers

Properties [91]: Thin layers are a compromise between the acoustical performances of single or two-layer porous asphalt and the durability of normal SMA. In order to get an optimized texture, generally small aggregate sizes are used. Noise reduction is due to this good texture and not to noise absorption: due to the low layer thickness, the absorption peak in the absorption curve lies at a frequency which is too high (around 2000 Hz) in order to play a significant tool. Nevertheless, the porous version is very effective to prevent air pumping [92]. Mixtures are often reinforced by addition of elastomers or fibres. Due to their stony skeleton, they resist well to rutting. According to French results, noise reduction of thin layers is between 0 and 3 dB (A) with respect to the reference surface dense asphalt concrete [93]. The Dutch IPG7 reports a reduction of 4 up to 7 dB (A) for porous thin layers and 3 up to 5 dB (A) for the SMA-type mixtures [91]. History: Thin layers have been used in France since de mid 1990ties. There is some renewed interest in this type of surfaces, especially in The Netherlands, as they are considered in the frame of the IPG as a valuable alternative (reasonable costs for construction and maintenance, reasonable durability and quite good acoustical properties) for the two-layer porous asphalt, the quietest road surface so far (see below).

3.2 Porous surfaces

• Single layer porous asphalt

Definition: this is a wearing course with a high stone content (typically 81-85%) with a typical grading of 0/14 with a gap at 2/7 resulting in a high void content (typically 20 %). Thickness is about 4 cm [78]. Properties: The low noise aspect of porous asphalt is due to its good absorption of both rolling and power train noise, which leads to a noise reduction of on average 3 dB(A) at higher speeds. The use of the coarse aggregates leads to a surface texture with some megatexture and is hence far from ideal. There is a large variety on the acoustical performances of single layer porous asphalt. In certain cases, a higher noise reduction (up to 9 dB(A)) has been reported, in other cases one measured an increase of the rolling noise of up to 3 dB(A) [94, 95, 96]. Hence it cannot always be considered as a low noise road surface. Porous asphalt has some advantages compared to dense wearing courses: during rain the water does not form a film on the road surface, avoiding the dangerous

7 Innovatie Programma Geluid (“Noise Innovation Programme”).



splash and spray effect and the reflecting of lights is avoided. The absence of an increase of noise in rainy conditions is an important advantage, especially in those regions with a lot of rainfall. Due to its stony skeleton, porous asphalt resists very well to rutting, but it is more sensitive to ravelling. Another problem is the clogging of the pores, decreasing the acoustical performance of the road surface. Also winter maintenance problems have been reported. History: Porous asphalt has been used especially on highways since the beginning of the 1980ties in a number of countries, especially in France, Belgium, Italy and the Netherlands. E.g. in the Netherlands, it is the standard road surface for highways since the end of the 80ties [92]. In Italy, about 10% of the highway network of AUTOSTRADE has been provided with a porous asphalt wearing course [78].

• Two-layer porous asphalt Definition: two layer porous asphalt consists of a sub layer of porous asphalt with a coarse grading (typically 0/14, 0/16, 11/16) and a typical thickness of 4,5 cm, with on top a wearing course with a fine aggregate (typical 4/8, but sometimes even 2/4 or 2/6) with a typical thickness of 2,5 cm. Properties: two-layer porous asphalt combines an optimized surface texture (densely packed grid of fine aggregates) with an optimized noise absorption in the appropriate range of the noise spectrum (between 500 and 1000 Hz), due to a high void content (typically 25 – 30 %). The acoustical performance is initially excellent: the noise reduction is 4 - 6 dB(A) for passenger cars at 50 km/h [97], and two-layer porous asphalt is among the quietest road surfaces which are actually in use. The versions with the finest aggregates (2/4, 2/6) on the top layer perform on average about 1,5 dB(A) better than those with coarser aggregates (4/8) [98]. In the frame of the Noise Innovation Program, one aims even at noise reductions of 7 up to 9 dB(A) for “optimized two layer porous asphalt” [99]. The good acoustical properties are combined with the series advantages which were mentioned for the single layer porous asphalt above. Unfortunately, also the two drawbacks for single layer porous asphalt exist for two layer porous asphalt: it has the tendency to clog, decreasing its acoustical performances with roughly almost 1 dB(A)/year [100] and it’s sensitive to ravelling. Nevertheless, there are indications that the technical lifetime of the two layer porous asphalt in the Netherlands is increasing by the technical improvements [101]. History: the concept of two-layer porous asphalt has been developed in the Netherlands and the first section of this road surface type was built there in the beginning of the 1990ties, and since then about 40 sections are built in the Netherlands on local and secondary roads. Numerous other sections have been built on highways. From the mid 1990ties, about 20 mainly test sections were built in several other European countries. From 2001 on, about 100 sections have as well been realized in Japan. See [101] for a survey.



• Porous cement concrete

Definition: Porous cement concrete is made with almost the same mixture as porous asphalt, but as binder one uses cement instead of bitumen. A variant is Modieslab, which has been developed by a Dutch firm: the road is built with prefabricated two layer porous cement concrete slabs. They are self supporting and especially designed for use in areas with unstable underground [103]. Properties: Acoustical performance of porous cement concrete is of the same order as porous asphalt [35], sometimes even slightly better [102]. One expects a better durability and less clogging than with porous asphalt, but this has not been proven yet experimentally. This type of road surface is very expensive, partly due to the use of polymer additives in the mixture. Construction is also quite delicate: it is more difficult to avoid megatexture as the surface is not rolled like a bituminous surface. History: Porous cement concrete sections have been built in several countries, especially in the USA, Germany, the Netherlands and France since the end of the 1980ties.

• Euphonic pavements

Definition: a road surface with on top a porous wearing course of 40-60 mm with underneath a continuously reinforced concrete slab, with built in Helmholtz resonators of about 500 cm³. Properties: Although earlier laboratory results with this concept were quite promising8, the only once it has been realized in full scale (on the highway between Rome and Anagni in Italy in the frame of the EC funded SI.R.U.US-project) was not convincing. Noise measurements revealed a good noise performance, but which was basically 1 – 2 dB(A) less good than the performance of the adjacent “ordinary” two layer porous asphalt [104] hence, so far the extremely expensive construction doesn’t seem to be justified by an extraordinary noise performance. History: This pavement was developed by Ejsmont in the 1980’s during a scholarship at the University of Götingen, and around 1990 some limited trials were made at VTI in Sweden [35]. The idea was picked up in the late 1990’s in Italy, which resulted in the only full scale realization so far on the motorway Anagni-Rome (see above).

3.3 Elastic surfaces

• Rubberized asphalt Definition: dense asphalt concrete or SMA surface with a certain percentage of rubber granulates added to the mix

8 See discussion in [78]



Properties: Rubber may be added as granules to a bituminous mix (typical 3 to 6 % by total weight). This is the so called “dry” process, and one speaks about “rubberized asphalt” Rubber may also be added as a powder (up to 15 %, typically 7 %) to modify the binder (the “wet” process). The wet process is sometimes used to improve binder quality in porous surfaces. According to Sandberg, there was until 2002 no conclusive evidence that the adding of small quantities of rubber to a bituminous wearing course would significantly reduce the noisiness of it [35]. On the other hand, Donovan [105] did in 2004 a comparative measurement campaign both in the USA (Arizona & California) and Europe with his CPX-like measurement device based on sound intensity technique. He found noise levels for two layer porous asphalt between 94,5 and 96,5 dB(A) and for the so called Rubberized Asphalt Concrete (RAC) between 95,5 and 97,5 dB(A). The RAC is a non porous SMA like wearing course with a thickness of 2,5 cm and containing 8 up to 10 % binder. The asphalt-rubber mixture contains typically between 14 percent and 20 percent rubber by weight of the total asphalt-rubber mixture [106]. History: The process of rubberized asphalt was originally developed in Sweden, where it was called RUBIT. In the USA it is called Plusride. The Asphalt-Rubber is described in an ASTM-standard (ASTM D8-88). See further [35].

• Poro-elastic surfaces Definition: A poro-elastic road surface (PERS) is a wearing course for roads with a very high content of interconnecting voids so as to facilitate the passage of air and water through it, while at the same time the surface is elastic due to the use of rubber (or other elastic products) as a main aggregate. The design air void content is at least 20% by volume and the design rubber content is at least 20 % by weight. Properties: The typical mixture for a PERS consists nowadays of cubic and/or fibre-like rubber particles (new rubber or from scrapped tires), sometimes stony aggregates, sand or another friction enhancing agent, glued together with a polyurethane or another artificial resin. Typical thickness is 3-4 cm. The PERS can be made on site or be prefabricated as mats, which are glued to the hard sub layer. The typical glue for this is epoxy resin. PERS shows generally extremely high noise reductions (typically 10 up to 12 dB(A)). Reported problems are insufficient binding to the hard sub layer, damage by snow ploughs and insufficient skidding resistance. The actual formulations are also quite expensive, due to the high content of costly ingredients (resin). This type of road surface is still in an experimental stadium. An extensive state of the art of this surface type can be found in reference [54]. History: PERS has been invented at the end of the 1970ties in Sweden by Mr. R. Nilsson. Early trials have been done in Sweden in the 1980ties. A limited experiment in 1989 in Norway was aborted after the destruction of the test section by a snow plough. Since 1994 the Public Works Research Institute of Japan is also doing research on PERS and since 2000 there is collaboration with the Swedish VTI, concentrating on remaining problems like adhesion to base course, wear resistance, wet friction, cost and fire



resistance. After some experiments with limited success since then, most likely research will be continued in Sweden, Japan and possibly also in some other countries, as the surface type is extremely interesting from an acoustical point of view and it offers a variety of additional advantages (like the possibility to recycle worn tires).



4 Measurement methods and standards

4.1 Introduction In this chapter, we are reviewing the measurement methods and standards that are currently used to evaluate the influence of a road surface on traffic noise. There are three basic methods for determining the noise performance of a road surface:

• The Controlled Pass-By method (CPB) • The Statistical Pass-By method (SPB) • The Close Proximity method (CPX)

and three auxiliary measurement methods for determining noise-relevant surface characteristics:

• Surface texture measurement • Sound absorption measurement • Mechanical impedance measurement

The latter series can serve either as substitutes or as complements to the basic methods.

4.2 Noise measurements methods

4.2.1 Controlled pass-by (CPB) In this method, the peak noise level of vehicles is measured when they pass in front of a microphone fixed at 7.5 m meter from the centre line of the measured lane and at 1.2 m above ground. The vehicles here have been purposely chosen as reference vehicle/tyre combinations; hence, the term « controlled ». Depending on the aim of the measurements, the test conditions may widely vary. The operating conditions of the vehicle may for instance be normal cruising or coasting by, engine off, to specifically study tyre noise. The vehicle speed may be chosen; however, measurements have to be corrected for speed in order to be able to be compared on an equal speed basis. In cruising conditions, different gear ratios may be selected. The surface may be wetted if one wishes to study the effect of rain, etc. To our knowledge, there are two published procedures: the BRRC method [16] using a single car and the so-called French-German Procedure relying on a set of four representative car/tyre combinations [17, 40]. The latter is applied in France and Germany to characterise the acoustic performance of a road surface with respect to tyre noise. Measurements are performed with a limited set of light vehicles, not with trucks. Both procedures may be – and have been – used to measure tyre noise only by turning off the engine when the vehicle approaches the microphone. In this case, it is called « coast-by » instead of « pass-by » method. Since the microphone position is the same, the method is compatible with ISO 362 [41] and ISO 7188 [42]. It can then be used to study the contributions of various factors to the vehicle noise levels as determined by the latter standards.



4.2.2 Statistical pass-by (SPB) The noise measurement set-up is exactly as in the CPB method; however, the measured vehicles are those freely running into the traffic stream. One measures the peak noise level of each individual vehicle picked out of the undisturbed traffic along with its speed by means of a radar tachometer. Plotting noise level versus log(speed) for different categories of vehicles and calculating the regression line allows characterising each vehicle category by an average noise level at any reference speed. A certain minimum number of vehicles in each category is required to get an acceptable significance interval and for the characteristic level to be reasonably representative of that category. That method has become an ISO standard [43] and is being taken into consideration by CEN/TC227/WG5 to be taken over as a European standard. The minimum numbers of vehicles per category and the reference speeds per category in relation to the type of road envisaged are prescribed. From the reported values, the standard proposes to characterise the road surface by a «Statistical Bass-By Index (SPBI)» which is an aggregate (overall) level of road surface influence on traffic noise for a mix of different categories of vehicles, the reference speeds and the weights assigned to light, medium and heavy vehicles being adapted to be representative of three road categories, namely: low-, medium- and high-speed roads. By adapting the reference speeds and weights of the different categories, one may define SPB indices specific to different traffic conditions like, urban versus rural for instance. The method requires the site to be free of sound reflecting objects over a large area round the microphone, which is often impossible in urban streets. That is why work has been carried out in the UK to develop an extension to the standard SPB method to allow its use over a wider range of site conditions [62, 63]. This method uses a reflective backing board placed directly behind the receiver microphone. Such an approach is being considered for adoption by the ISO Working Group that is responsible for revision of the ISO standard describing the SPB method.

4.2.3 Close proximity (CPX) In this method, one or several microphones are placed very close – typically 20 cm from the tyre side wall - to the tyre for measuring near-field tyre noise emission while rolling. The tyre can be either on one of the wheels of a normal vehicle or of a special trailer. In either case, severe protection measures must be taken to prevent the measurement to be influenced by wind turbulence, noise from traffic and noises from the vehicle or from the trailer or both. Specifications have been developed in an ISO Committee Draft. The most critical ones bear on the choice of the reference tyre(s) and on the precise microphone position(s) because it has been observed that the latter have a very important influence on the measurement results. The work is still presently on-going. Quite a number of CPX vehicles or trailers have been developed in Europe, all different. Twenty-one trailers and four instrumented cars had been identified in 1998 [44]. To our knowledge, there are presently such devices in service in The Netherlands, in United Kingdom, in Germany, in Austria, in Poland and in France. Several comparisons (Round Robin Tests) have been carried out [33, 45, 46, 47, 48], the outcomes of which have consistently shown serious discrepancies between the different devices.



4.2.4 Comparison between noise measurement methods The main interest of the CPX method is that it can be implemented in urban situations: it is not disturbed by acoustic reflections of nearby buildings like the pass-by procedure. Another advantage is that the road surface can be tested in a continuous way while the pass-by method is only representative of the spot facing the fixed microphone. However, methods using microphones close to the tyre lack of realism because the far field, where human receivers are, can be very different from the near field due to interference between correlated sources. One of the main problems with the near-field procedure is to obtain measured values well related to pass-by values. The difference between near-field and far-field comes out to be significantly dependent on speed, tyre, sound frequency and acoustical impedance (absorption) of the road. Recent comparisons carried out in the frame of SILVIA have shown that the correlation is generally poor between SPB and CPX results and the regression equations appear significantly different for different CPX devices (Table 4) [33].

Table 4 – Results of comparisons between SPB and CPX by different laboratories

CPX equipment Regression equation Corr. Coef. R2 Residual σ (dBA) Arsenal (AT) SPB = 1,10·CPX --- 28,9 dBA 0,96 0,70 DWW (NL) SPB = 1,22·CPX --- 42,3 0,56 1,47 M+P (NL) SPB = 0,79·CPX + 2,0 0,40 1,63 TUG (PL) SPB = 1,22·CPX --- 40,9 0,95 0,73 Also because no propagation effects are taken into account like sound absorption by porous surfaces which are then likely to be underestimated regarding their noise reduction potential. Lorry tyres are not easy to test. The majority of existing CPX test devices is for car tyres. The CPX method obviously lacks reproducibility (between different pieces of equipment) and representativity (of the actual traffic noise). In addition, it is to be noted that, even though SILVIA has developed a procedure, how to determine the intrinsic background noise of a CPX device remains a difficulty. The CPB method seems more realistic than the CPX method since it can take into account the total noise of vehicles. However, since it relies on an arbitrary set of vehicles, its representativity remains questionable. The representativity issue is almost completely solved by the SPB method since it takes into account all types of vehicles in normal driving condition. The only caveat is about the repeatability and reproducibility if one considers that the sample of vehicles is always different form one measurement to another. The differences are assumed to be averaged out thanks to the minimum, statistically significant number of vehicles specified to be measured in each category. However, one might argue that comparisons between roads in different countries or regions could be affected by differences in some characteristics of the vehicle fleets.



That problems remain to be solved is illustrated by Project group 5.1 of IPG [63]. Their goal is to define a set of unambiguous, standardised measurement and assessment methods which will improve the exchange and use of measurement data and which can be used in the technical content of regulations and legislation. To achieve that goal, they have identified the following sub-projects: • A literature survey to describe the current status of normative standard measurement methods, • A study of the relationship between SPB and CPX measurement results, • A European assessment method (from the SILVIA project) for evaluating the noise effects of road surfaces (product labelling, conformity of production, monitoring), • Overcoming problems with the current CPX method, • Harmonisation of the characterisation of texture by means of spectral analysis, • Study of rolling resistance.

4.3 Auxiliary measurement methods

4.3.1 Surface texture As stated in Chapter 4, the main surface characteristics that determine tyre/road noise are macro- and megatexture. Despite modern methods are widely available, macrotexture is still often measured (essentially for work acceptance testing) by means of the so-called “Sand Patch” or a similar “volumetric method”. The method is an ISO [49] as well as a CEN standard [50]. However, as it does not cover the important megatexture range, it is not sufficient with respect to noise. Modern profiling devices using lasers are now able to measure the whole range of macro- and megatexture at once. There are static versions, transportable or mobile (stop, measure and go), as well as dynamic devices capable of measuring at traffic speed. That type of equipment is subject to a set of ISO standards either already published or in development [51, 52, 53, 113, 114]. See §4.4.2.

4.3.2 Sound absorption The sound absorption coefficient is the fraction of sound energy absorbed by a material when a sound wave is reflected by its surface. It generally depends on the frequency of the sound considered (or its spectrum when it is not a pure sound) and the angle of incidence of the sound wave. The sound absorption coefficient of a surface is usually evaluated for plane wave incidence conditions. It can be measured by various methods: • the so-called impedance tube method also referred to as the “Kundt’s tube”: the basic

principle is that when the lateral dimensions of a tube are small compared to the wavelength of the acoustic signal, only planes waves will propagate. The sample, placed at one end of the tube is submitted to normal incident wave fronts. The absorption coefficient is derived from the shift of the nodes of the stationary wave in presence of the sample. Two variants of the method are ISO standard [37, 56].



• the external point source method: if a point source is far enough from the measured surface, the spherical wave front geometry can be approximated by a plane wave front. Depending on the relative positions of the source and the microphone, normal or oblique incidences can be considered. This impulse method is in fact an ISO standard [36] adapted from the AFNOR standard S 31-089 for the on-site determination of the absorption coefficient of absorbing materials used in the construction of noise screens.

• the reverberant room method: in a room with very reflective walls (no absorption) the spatial sound distribution becomes diffuse. A sample placed in such a room is submitted to an acoustically diffuse field (random incidence distribution of plane waves). The absorption coefficient is derived from the decrease of the reverberation time and from the relative area of the sample and the room walls. The method is an ISO/CEN standard [57].

For road surfacing materials, using the reverberant room method requires a rather large flat sample of the road surface to be either prepared in the laboratory or taken out of the road itself, which is not practical. For the tube method, a sample must be bored out of the road surface in the form of a core of appropriate diameter. However, an in situ version has been developed in the Netherlands [58]. It uses a transportable tube to be applied vertically onto the surface. The external point source method is the most suitable for field use. It can be either mounted on a static frame or attached to a van, in which case the measurements can be made moving (stop, measure and go) or dynamic (non-stop, repeated measurements). Such mobile systems are already in service in Italy [59] and in UK [60].

4.3.3 Mechanical impedance Mechanical impedance is the complex ratio between the dynamic force and the resulting displacement of a surface submitted to that force. For simplicity and understanding one uses the term “stiffness”. The stiffness of the pavement has sometimes been put forward as the reason for the difference of noisiness between Cement Concrete and Asphalt. It has been shown that, once the influence of texture is accounted for, there is no significant difference in noise performance between the two materials [61]. It has been further demonstrated by SILVIA that, for a road surface stiffness to have any significant influence on tyre/road noise, the surface material must have a stiffness comparable to that of the tyre. That condition is now met with the so-called “Poro-elastic road surface” (PERS) made of rubber from scrap tyres. Now, if that innovative material proves effective and starts spreading, a test method for its stiffness will become necessary. That is why, in SILVIA, a tentative measurement method has been tested [33]. Further developments are still needed for a method to be ready for standardisation.

4.4 Standardization This chapter reviews the progress achieved in the relevant international (ISO) and European (CEN) standardization.



4.4.1 Noise measurement methods Regarding the determination of the noise performance of a road surface based on vehicle noise measurements, two methods are to be taken into consideration: SPB and CPX. The CPB method as such is not standardized at international nor European level. CPB is not to be recommended for standardization because the results are essentially dependent of a few vehicles, even only one in some reports. Therefore, representativity and reproducibility of the method are questionable. However, let us quote as a reminder that ISO standards do exist that specify the test procedure for determining the noise emitted by road vehicles in completely controlled conditions and environment, including a reference surface (ISO 10844:1994). This is for type approval purpose of either vehicles (ISO 362:1998 and ISO 7188:1994) or tyres (ISO 13325:2003). The SPB method is standardized as ISO 11819-1:1997 [43]. It is presently in the revision process by ISO Working Group ISO/TC43/SC1/WG33. The CPX method has been in development for several years. A committee draft has been circulated for some years, namely ISO/CD 11819-2:2000 [38]. The essential issue pertains to the representativity and the enduring availability of the types of reference tyres to be used. Working Group ISO/TC43/SC1/WG33 is presently trying to overcome the difficulties.

4.4.2 Auxiliary measurement methods Regarding the auxiliary methods, only texture and sound absorption have been subject to international or European standardization. There is no standard applicable to the measurement of road pavement surface stiffness in a way relevant to noise. In the beginning of the studies on tyre/road noise, namely in UK in the early 1970’s, macrotexture was first suspected to be the main factor determining tyre/road noise on different surfaces. At that time, macrotexture was measured by means of the so-called Sand Patch Test delivering a Mean Texture Depth (MTD). That test is still in use for some purposes related to skid resistance and also to noise as in the HAPAS scheme (see § 5.2.12). The Sand Patch Test is standardized at European level in EN 13036-1:2001 where it has been re-worded as Volumetric Patch Test because it makes use of glass beads instead of sand. Modern technology using lasers is capable of determining even at traffic speed the so-called Mean Profile Depth (MPD), which can be converted into MTD values. MPD has been standardized first by ISO (ISO 13473-1:1997) and taken over later by CEN (EN ISO 13473-1:2001). That new technology soon required some clarification regarding new specific terms, profile data processing, specifications for the prolfilometers and their classification. This is provided by two associated standards, namely ISO 13473-2:2002 and ISO 13473-3:2002. However, later research resorting to spectral analysis of surface profiles showed that simple measures like MTD and MPD were not sufficient to characterize the surface influence on tyre/road noise. Megatexture was identified as another very important factor (see Chapter 2). A method for determining megatexture is presently taken into consideration by CEN after an ISO Committee Draft (ISO/CD 13473-5:2005) not yet turned into a standard. Finally, as precise determination of noise-



relevant macro- and megatexture calls for spectral analysis of the road surface profile, an ISO Technical Specification for pavement profiles spectral analysis is under development (ISO/CD TS 13473-4:2004). Working Groups ISO/TC43/SC1/WG39 and CEN/TC227/WG5 are presently dealing with road surface texture measurements. Sound absorption of road material samples can be determined in a reverberation room provided they cover a sufficient area (e.g. one m2); therefore, ISO 354:2003 or EN 20354:1993 can be used. Cores can be either made in the laboratory or bored out of the road surface and fitted into a so-called Kundt’s tube or impedance tube in order to determine their sound absorption spectrum. Two slightly different methods are standardized: ISO 10534-1:1996 and ISO 10534-2:1998. In search of more practical, non-destructive methods in-situ, some new methods have been or are being developed. The so-called “Extended Surface Method” is specified in ISO 13472-1:2002. It consists of comparing an acoustic signal reflected by the surface to the signal sent onto the surface, using a loudspeaker and a microphone. As there is no contact with the surface, the measurement can be made mobile. Another non-destructive, in-situ method uses a variant of the impedance tube so-called “Guard tube” applied directly on the road surface. Two slightly different versions of a draft standard are presently under development (ISO/CD 13472-2:2005 and ISO/CD 13472-3:2005). Working Group ISO/TC43/SC1/WG38 is presently dealing with sound absorption measurement methods applicable to road surfaces. Table 5 summarizes the present state of progress of standardization.

Table 5 – Present state of progress of the relevant standardization.

Subject Document Ref. Comments Reference surface ISO 10844:1994 [49] Currently under revision Vehicle noise ISO 362:1998 [41] Vehicle noise ISO 7188:1994 [42] Tyre/road noise ISO 13325:2003 [115] Surface influence ISO 11819-1:1997 [43] Currently under revision Surface influence ISO/CD 11819-2:2000 [38] In development

Sound absorption ISO 354:2003 EN 20354:1993 [57]

Sound absorption ISO 10534-1:1996 [56] Sound absorption ISO 10534-2:1998 [37] Sound absorption ISO 13472-1:2002 [36] Sound absorption ISO/CD 13472-2:2005 [111] In development Sound absorption ISO/CD 13472-3:2005 [112] In development Macrotexture EN 13036-1:2001 [50]

Macrotexture ISO 13473-1:1997 EN ISO 13473-1:2004 [51]

Macro- & megatexture ISO 13473-2:2002 [52] Macro- & megatexture ISO 13473-3:2002 [53] Macro- & megatexture ISO/CD TS 13473-4:2004 [113] In development

Megatexture ISO/CD 13473-5:2005 [114] In development. Under consideration to be taken over by CEN.



5 Noise classification of road pavements

5.1 Introduction We have identified sixteen countries among which twelve EU Member States that are applying some kind of noise classification of road surfaces for different purposes. We are reviewing hereafter the available information from each of those countries. In addition, we are quoting two recently completed European projects that have brought interesting contributions to the subject.

5.2 State-of-the-art at national level

5.2.1 Austria In Austria, a model is used that is called RVS 3.02. The road surface corrections Csurf used in RVS is dependent on vehicle category and vehicle speed as shown in Table 6 [1].

Table 6 - Road surface correction in the Austrian model RVS3.02

Those values are based on SPB and CPB measurements converted in Leq values. Subsequently, guidelines were issued describing a measurement method using a home-made trailer [2] that was used in an investigation by ARSENAL Research [3]. The measurement campaign covered 11 road sections with different surface materials. Measurements were carried out using four methods, namely: trailer complying with RVS11.066 delivering ”LMA-values”, trailer complying with ISO/CD 11819-2 [38]



either using all four tyres (E9, B, C, D) delivering “CPXI4-values” or tyres E & D delivering “CPXI2-values” and SPB according to ISO11819-1 [43] delivering “SPBI-values”. The results are given in Table 7. From those results, the correlations between trailers appear to be excellent (0.95<R2<0.97) while the correlations between any trailer and SPB method are rather poor (0.26<R2<0.30). The ranking of surfaces happens to be much dependent of the measurement method as Figure 3 shows.

Table 7 – Summary of Austrian measurement results [3]

Road surface RVS11.066-IV ISO/CD11819-2 ISO11819-1 N° Type LMA CPX4 CPX2 SPBI

1 Exposed aggregate cement concrete 1 101.2 103.3 103.4 85.8

2 Exposed aggregate cement concrete 2 100.5 102.5 102.8 86.7

3 Cement concrete 103.2 104.3 104.3 86.9 4 Thin layer 1 102.1 103.5 103.4 84.6 5 Thin layer 2 101.7 - 104.6 - 6 SMA 1 99.6 102.4 102.5 84.4 7 SMA 2 102.5 - 103.9 - 8 Porous asphalt 1 103.0 - 103.7 - 9 Porous asphalt 2 101.8 103.5 103.9 84.5 10 Asphalt concrete 1 102.2 102.3 102.8 87.8 11 Asphalt concrete 2 103.3 - 103.5 85.8

5.2.2 Belgium Referring to the German calculation scheme (RLS-90, see § 5.2.4), the Brussels Institute for Managing the Environment (IBGE-BIM) applies corrections determined for the 5 types of surfaces encountered in the Brussels Region (Table 8) [110].

Table 8 – Corrections applied by the Brussels Region

Surface type 30 km/h 40 km/h 50 km/h 70 km/h 100 km/h Porous asphalt -2.0 -1.0 SMA 0.0 0.0 0.0 0.0 0.0 Asphalt concrete Gussasphalt Surface dressing

+1.0 +1.5 +2.0 -2.0 0.0

Cement concrete (slabs & blocks) +2.0 +2.5 +3.0 +3.0 +3.0 Cobble stones +2.0 +4.5 +6.0 +4.0 +6.0

9 An alternative for ISO tyre A.



83

84

85

86

87

88

89

6 9 4 1 11 2 3 10

Surface n°

dB(A

) SPBILMA-16 dB(A)

Figure 3 – Ranking of surfaces versus the measurement method in the Austrian noise measurement campaign [3]. SPBI is the SPB Index according to ISO 11819-1

[43]. LMA is the Austrian CPX trailer with 16 dB(A) subtracted to the CPX level.

5.2.3 France In France, the calculation method developed in the seventies [4] does not consider the influence of the road surface. Presently, work is in progress with a view to updating the procedure, namely by including that influence and also taking into account the evolution of vehicle technology [5, 6]. So far, formulas predicting the level of the rolling noise component have been established for different categories of surfaces versus vehicle category and speed as in Table 9.

Table 9 – Rolling noise level (LAmax at 7.5 m) versus speed, surface category and vehicle category. The speed range is 5 to 130 km/h for light vehicles and 5 to

100 km/h for heavy vehicles

Surface category Light vehicles Heavy vehicles R1 73.8 + 30.2 log(V/90) 83.8 + 26.0 log(V/90) R2 77.7 + 31.5 log(V/90) 87.2 + 31.0 log(V/90) R3 80.2 + 32.2 log(V/90) 88.3 + 32.6 log(V/90) The surface categories include the following (Table 10):

Table 10 – Road surface categories in the French updated calculation method

R1 R2 R3 Very thin asphalt layer 0/6 (types 1 & 2) Ultra thin asphalt layer 0/6 Porous asphalt 0/10 Very thin asphalt layer 0/10 (type 2)

Very thin asphalt layer 0/10 (type 1) Dense asphalt concrete 0/10 Cold mix Ultra thin asphalt layer 0/10

Cement concrete Very thin asphalt layer 0/14 Dense asphalt concrete 0/14 Surface dressing 6/10 & 10/14

It is to be noted that there is no reference surface. The formulas are not corrections: they give the contribution of tyre/road noise in terms of noise levels.



5.2.4 Germany The German guidelines “Richtlinien für den Lärmschutz an Strassen, 1990” (RLS90) include the surface corrections (“DStrO”) n° 1-4 presented in Table 11a in their prediction model [7].

Table 11a - Road surface correction according to the German prediction model

DStrO in dB(A) at posted speed limit of Road surface

30 km/h 40 km/h 50 km/h

1 Non-grooved Gussasphalt Asphalt concrete Stone mastic asphalt

0 0 0

2 Cement concrete Grooved Gussasphalt +1,0 +1,5 +2,0

3 Paving stones with even surface +2,0 +2,5 +3,0 4 Miscellaneous paving stones +3,0 +4,5 +6,0

There are additional surface corrections included in “Allgemeines Rundschreiben Straßenbau Nr. 14/1991” [34] presented in table 11b.

Table 11b – Road surface correction according to the German prediction model

Road surface DStrO in dB(A)

for rural roads with speeds > 60 km/h

5 Cement concrete after “ZTV Beton 78” with steel brush with longitudinal smoothing +1,0

6 Cement concrete after “ZTV Beton 78” without steel brush with longitudinal smoothing, textured with burlap -2,0

7 Asphalt concrete ≤ 0/11 and stone mastic asphalt 0/8 and 0/11 without loose chippings -2,0

8 Open porous asphalt with a void content ≥ 15 % after construction with grain size 0/11

-4,0

9 Open porous asphalt with a void content ≥ 15 % after construction with grain size 0/8 -5,0

The corrections can be determined using either the SPB or the CPB method according to GEStrO-92 (“Geräuschemission von Strassenoberflächen, 1992”) [8].

5.2.5 Hungary Guidelines have been recently issued by the Hungarian Ministry of Environment and Water [9]. They specify the investigation and calculation methods for establishing strategic noise maps. They include corrections to be applied on the traffic noise level as in Table 12. The indicator is LAeq at 7.5 m. The correction applies equally to daytime, evening and night traffic noise levels.



Although it is not explicitly quoted as such, the reference surface can be considered here as a Dense Asphalt Concrete similar to many other reference surfaces.

Table 12 – Road surface corrections in the guidelines of the Hungarian Ministry of Environment and Water

Road surfaces Category Types

Correction dB(A)

A

Dense asphalt concrete (0/8) Dense asphalt concrete (0/12) Stone mastic asphalt (0/8) Mastic asphalt (0/8) Mastic asphalt (0/12) Modified thin asphalts layers

0

B

Dense asphalt concrete with polymer-modified binder Mastic asphalt with polymer-modified binder Thin asphalts layers older than 4 years Stone mastic asphalt (0/12) Modified stone mastic asphalt (0/12) Surface-dressed asphalt concrete (0/12)

+2.9

C

Dense asphalt concrete with polymer-modified binder older than 4 years Mastic asphalt with polymer-modified binder older than 4 years Single and double surface dressing (5/8, 2/5) Dense asphalt concrete (0/16) Surface-dressed asphalt concrete (0/16) Dense asphalt concrete (0/20)

+4.9

D

Cement concrete Cracked asphalt concrete Dense asphalt concrete (0/16) older than 4 years Surface-dressed asphalt concrete (0/16) older than 4 years Dense asphalt concrete (0/20) older than 4 years

+6.7

E

Fretted or plucked cement concrete Small sett paving Ornamental paving blocks Ceramic blocks Chipped sand asphalt (0/16) Chipped sand asphalt (0/20)

+7.8

5.2.6 Italy In Italy, there are software models for noise prediction by the name Citymap and Disiapyr [10]. These include a road surface correction table, which appears in Table 13. This table is unique in that it includes corrections in octave bands, not just a flat correction for the A-weighted overall level. It also includes, as the two last lines, a correction for longitudinal road gradient, one for driving 5 % uphill and another for driving 5 % downhill.



Table 13 - Road surface correction in the Italian model Citymap [10]. The last two lines are corrections for longitudinal road gradient

Road surface 63 Hz 125Hz 250Hz 500Hz 1 kHz 2 kHz 4 kHz 8 kHz dB(A) Conventional asphalt pavement (reference)

81.7 87.4 81.4 76.2 75.1 73.8 70.6 71.1 81.3

Paving stones +1.1 +1.2 +2.1 +2.3 +1.5 +1.6 +1.8 +1.3 +1.9

Drainage asphalt pavement -0.1 -0.3 -1.1 -1.8 -2.4 -2.1 -1.2 -1.3 -1.4

Conv. asphalt, gradient + 5 % +2.2 +2.4 +3.1 +2.1 +2.0 +1.3 +1.6 +1.4 +2.2

Conv. asphalt, gradient - 5 % -1.2 -1.3 -0.8 -1.1 +1.0 -0.2 +0.7 +0.8 +0.1

5.2.7 Japan The model used in Japan is called the ASJ Model. The latest version is from 1998 [11]. This model contains a surface correction, but only for porous asphalt pavements (PA 0/13, usually having about 20 % voids in new condition) in relation to "normal" dense asphalt pavements (DAC 0/13), the former being the most used for noise reduction. The correction is valid over the speed range 40-140 km/h for light vehicles and 40-120 km/h for heavy vehicles, and it is as follows [12]:

2.3)log(5.3 +−= VCorrection (1) Where V is the vehicle speed in [km/h]. The Japanese are going to revise this model. One of the improvements considered is to take the age of the surface into account. Tyre/road noise levels are measured by means of special vans (“Road Acoustic Checker”) equipped with a special tyre as a fifth wheel. The method resembles the CPX method. The tyre is a normal Bridgestone tyre for which the normal tread has been buffed-off and a new tread has been fitted with a very special tread pattern. The tread pattern consists of large “suction cups” on one side of the tyre and large “crossbar lugs” on the other side. In this way, both the vibrational impact mechanism and the air-pumping mechanism are excited in a maximum way. The classification of surfaces with this tyre does not correlate so well with the SPB method, since on smooth surfaces both mechanisms are excited to a very high degree. However, within the porous asphalt surface group, the main subject of the system, tested relations show a reasonable correlation CPX-SPB [32].

5.2.8 The Netherlands The Dutch official specifications for noise calculation and measurement [13] provides for a correction term for the road surface influence called “Croad”. It is as a function of vehicle category and speed if one uses the simplified procedure. It is also given by octave-bands if one uses the full procedure. It is defined as follows:



Simplified procedure: ⎟⎟⎠

⎞⎜⎜⎝

⎛+∆=

m

mmmmroad V

VbLC,0

, log (2)

Full procedure: ⎟⎟⎠

⎞⎜⎜⎝

⎛+∆=

m

mmimimroad V

VbLC,0

,,, log (3)

where m and i are respectively the subscripts for vehicle category and frequency band (octaves). That correction is to be applied with respect to a reference surface, which is a smooth, dense asphalt concrete. That surface is specified by means of its reference values given in Table 14 [14].

Table 14 – Reference values of the parameters in the equation of the noise level vs. speed of the reference surface: L = a + b log(V/V0)

a dB(A)

b dB(A)

V0 (km/h)

Light vehicles 74.8 33.0 80 Medium heavy vehicles 80.9 20.9 70 Heavy vehicles 83.5 22.5 70 The measurement method specified to determine Croad is the SPB with a microphone height of 5 m. Tables 15 & 16 list Croad values for light and medium/heavy vehicles respectively [15].

Table 15 – Corrections for the road surface to be used in the Dutch noise calculation procedure for light vehicles

N° Product type Vmin Vmax ∆L b 0 Reference surface asphalt 40 130 0,00 0,00 1 Single layer porous asphalt asphalt 50 130 -2,61 -8,02 2 Double layer porous asphalt asphalt 50 130 -5,05 -5,41 3 Double layer porous asphalt (fine) asphalt 50 120 -6,39 -5,38 4 SMA 0/6 asphalt 40 80 -1,91 -3,94 5 Exposed aggregates cement concrete cement 50 130 1,42 -0,21

6 Exposed aggregates cement concrete (optimized) cement 70 80 -0,07 -1,63

7 Finely brushed cement cement 70 120 1,63 5,09

8 Surface treatment asphalt / cement 70 130 2,29 -2,81

9 common pavement blocks blocks 40 60 4,00 0,00 10 Silent pavement blocks blocks 40 60 -2,18 -5,72 11 Thin layers 1 asphalt 40 80 -4,21 -7,24 12 Thin layers 2 asphalt 40 80 -5,71 -6,59 13 ZSA10 - open asphalt 40 50 -6,64 -10,62 14 ZSA - semi dense asphalt 40 60 -6,08 -7,10 15 Dubofalt asphalt 50 60 -6,01 -3,60 16 Nobelpave asphalt 40 50 -6,29 -8,52 17 ZSM11 asphalt 40 50 -5,76 -8,83 18 Micropave asphalt 50 80 -4,78 -4,89 19 SilentSTONE blocks 40 50 -1,43 -3,04 20 Viagrip asphalt 40 50 -6,36 -13,48 21 Geosilent blocks 40 50 -2,93 -8,48

10 ZSA is a product name of the company KWS. ZSA stands for “Zeer Stil Asfalt”, which means “Very Silent Asphalt” 11 ZSM is a product name of the company Temmink Infra B.V. ZSM stands for “Zeer Stil Mastiek”, which means “Very silent mastic”



22 Micro-Top 0/6 asphalt 50 60 -5,53 -5,97 23 Micro-Top 0/8 asphalt 50 70 -2,66 -3,36 24 Stilstone blocks 40 50 -2,61 -5,87 26 Redufalt asphalt 50 60 -4,67 -6,43 27 Accoduit asphalt 50 80 -1,28 -4,67 28 Novachip asphalt 60 80 -1,41 -2,63 29 Tapisville asphalt 40 50 -5,24 -9,06 30 Fluisterfalt asphalt 50 90 -5,36 -6,29 31 Microville asphalt 40 50 -6,11 -11,58 32 Microflex 0/6 asphalt 50 80 -4,81 -3,86 33 Decipave asphalt 40 60 -5,73 -6,96 34 Twinlay-m (*) asphalt 40 50 -6,60 -5,78 35 Silent Mastic asphalt 50 60 -5,85 -7,12 36 Bruitville asphalt 40 60 -4,63 -4,89 37 Duolay asphalt 110 120 -6,65 -4,27

(*) Also valid for 110 km/h.

Table 16 – Corrections for the road surface to be used in the Dutch noise calculation procedure for medium and heavy vehicles

N° Product type Vmin Vmax ∆L b 0 Reference surface asphalt 40 90 0,00 0,00 1 Single layer porous asphalt asphalt 70 100 -3,90 -6,05 2 Double layer porous asphalt asphalt 70 100 -6,28 1,02 3 Double layer porous asphalt (fine) asphalt 50 90 -5,66 -6,08 4 SMA 0/6 asphalt 50 70 -0,92 -3,33 5 Exposed aggregates cement concrete cement 70 100 -0,64 7,01

6 Exposed aggregates cement concrete (optimized) cement 70 80 -1,97 -4,01

7 Finely brushed cement cement 70 90 1,44 6,26

8 Surface treatment asphalt / cement 70 100 -0,70 4,27

9 Common pavement blocks blocks 40 60 4,00 0,00 10 Silent pavement blocks blocks 40 60 -0,01 0,00 11 Thin layers 1 asphalt 40 80 -1,73 0,00 12 Thin layers 2 asphalt 40 80 -3,36 0,00 14 ZSA12-semi dense asphalt 50 60 -4,25 0,18 34 Twinlay-m asphalt 80 80 -5,98 -1,73

5.2.9 Slovenia For taking the influence of road surfaces on traffic noise emission, they use the regulation that defines the method of evaluation of traffic noise impact on the environment [18]. The method is entirely based on German guidelines RLS – 90, according to which the corrections listed in Table 17 have been determined.

Table 17 – Road surface corrections specified in the Slovenian method for evaluating traffic noise impact on the environment [18, 19]

Surface types Correction (B(A)

Porous asphalt -3 Stone mastic asphalt -2 New asphalt concrete 0 Asphalt concrete with bigger chipping sizes +2 Old cement concrete +3 Flat paving stones +3 Damaged stone paving +6

12 See note 2.



From a subsequent measurement campaign covering Surface dressings, SMA’s, Porous asphalts and Dense asphalts [20], it appears that the correction is fairly well confirmed for SMA but not for PA, the noise-reducing performance of which is significantly underestimated by the guidelines (Table 18).

Table 18 – Comparison between subsequent measurement results and guidelines

Speed (km/h) AC SD SD-AC SMA SMA-AC PA PA-AC 50 71,7 70,4 -1,3 69,1 -2,6 65,7 -6,0 70 77,4 75,8 -1,6 75,2 -2,1 70,5 -6,8 90 80,7 79,0 -1,7 78,7 -2,0 73,5 -7,2 110 83,0 81,2 -1,8 81,3 -1,7 75,5 -7,5 Nr. of sections 12 1 16 2 Average -1,6 -2,1 -6,9 Guideline N.A. -2,0 -3,0

5.2.10 Spain There is no specific regulation about road surface influence on traffic noise. However, there are some mentions in two standards, namely:

• The standard about rehabilitation of pavements for the Road State Network [21] includes a paragraph in the section about resurfacing. It says that, in case the rolling noise should be reduced, it is possible to use porous asphalt or some SMA, always taking into account the other surface characteristics of these mixes.

• The standard for designing pavements in the Andalucia Region Road Network [22] says that, although in general it's not advisable to use porous asphalt (because of climatic constraints), they can be used in urban areas with ADT>2000 vehicles/day if noise reduction is needed.

Correction terms for road surface "noisiness" in calculations (noise mapping) have been proposed [23] (Table 19), which appear to have been take over from the Commission Recommendation of 6 August 2003 [107].

Table 19 – Proposed noise corrections for road surfaces in Spain

Correction dB(A) Surface types 0-60 km/h 61-80 km/h 81-130 km/h Porous asphalt -1 -2 -3 Smooth asphalt concrete 0 0 0 Cement concrete Rough asphalt concrete 2 2 2

Bald paving blocks 3 3 3 Harsh paving blocks 6 6 6



Now, measurements of rolling noise using the CPX method are underway. In the future, they are planning to start a research about the absorption measurement of different kind of pavements using MLS13 techniques.

5.2.11 Switzerland The Swiss noise calculation model “SonRoad” includes corrections for the road surface as in Table 20 [24].

Table 20 – Corrections for the road surface in the Swiss “SonRoad” calculation model

Surface type Correction dB(A)

Porous asphalt (0/8, 0/11) -4 « Macro-rough » asphalt14 (0/8, 0/11) -1 Asphalt concrete (0/8, 0/11, 0/16) Mastic asphalt (0/8, 0/11, 0/16) Surface dressing (3/6) Stone mastic asphalt (0/8, 0/11) Grainy asphalt mix15 Asphalt mix added with tar16 (0/10)

0

Surface dressing (6/11) Asphalt mix added with tar (0/16) +1

Sett paving +6 Table 20 is said to be valid for pavements between 3 and 20 year old. It is warned that the correction for the sett paving applies to tyre/road noise only while the other corrections are for the global vehicle noise. In our opinion, tyre/road noise anyway determines the global noise level in this case.

5.2.12 United Kingdom In the method used in the U.K., termed CRTN17, the correction is expressed as follows [25]: For roads which are impervious to surface water and where the traffic speed (V) is >75 km/h the following correction to the basic noise level is required: for concrete surfaces: Correction = 10 log (90 MTD + 30) - 20 dB(A) (4) for bituminous surfaces: Correction = 10 log (20 MTD + 60) - 20 dB(A) (5) where MTD is the texture depth measured by the sand-patch test. It means that the CRTN needs access to a measured or predicted texture depth. For road surfaces and traffic conditions which do not conform to these requirements a separate correction to the basic noise level is required. For impervious bituminous and

13 “Maximum Length Sequences” according to ISO 13472-1 [36]. 14 “Asphalt macro-rugueux” 15 “Enrobé bitumineux grenu” 16 “Enrobé avec adjonction de goudron” 17 Calculation of Road Traffic Noise.



concrete road surfaces, 1 dB(A) should be subtracted from the basic noise level when the traffic speed (V) is <75 km/h. Roads surfaced with pervious macadam have different acoustic properties from the surfaces described above. For roads surfaced with these materials, 3.5 dB(A) should be subtracted from the basic noise level for all traffic speeds. Later on, “the introduction of new proprietary and the failure of previous empirical relationship to accurately predict noise levels from measurements of road surface characteristics has led to the consideration of direct measurement of noise” [26]. This has been implemented in the HAPAS18 type approval system, according to which the influence of the road surface on traffic noise is determined using the SPB method. The result is expressed in terms of Road Surface Influence as follows:

9.951010578.0108.7log10 101010

10 -)++(=RSIL H2veh,L H1veh,L Lveh,

H ×× (6) for high speeds, and

92.3100.157100.6291011.8log10 10101010

21,

-)++(=RSILLL

MHveh,HvehLveh,

××× (7) for medium speeds.

5.2.13 USA In the Traffic Noise Model (TNM) used in the USA, the road surface correction is presented in Table 21 [27]. A mix of DAC and PCC constitutes the reference surface. The same correction applies for all speeds.

Table 21 - Correction in the US TNM model in dB(A) compared to the reference case

Automobiles Medium trucks & busses

Heavy trucks Motorcycles

Reference: A mix of DAC and PCC surfaces

0 0 0 0

Dense asphalt concrete -0.65 -0.64 -0.59 0 Portland Cement Concrete +2.36 +1.47 +0.72 0 Open-graded asphalt -2.20 -1.15 -1.66 0

5.2.14 Nordic countries Since first introduced in the 1970's, the five Nordic countries (Sweden, Denmark, Norway, Finland and Iceland) have had a common prediction model. The latest one is from 1996 [28] and has an optional road surface correction according to Table 22. This correction comes from [29] where its background is also described (see also [35]).

18 Higway Authorities Product Approval Scheme.



A new model called Nord2000 is presently being developed. It is scheduled to be completed by 31 March 2006. The newest version of the source model [Source modelling report 060102, only for distribution between project partners] is very brief concerning road surface characterisation. The road categories will be as in Table 23 [30]. This means that the very detailed list in the 1996 version will be replaced with a less detailed one.

Table 22 - Road surface correction table in the Nordic model, version 1996

Road surface Correction term in dB(A) for a certain % of heavy vehicles

0-60 km/h

61-80 km/h 81-130 km/h

No Type (max. chipping size also indicated here)

Age [year]

0-5

%

6-19

%

20-1

00 %

0-5

%

6-19

%

20-1

00 %

0-5

%

6-10

0 %

1.a Asph. concr., dense, smooth (≤12-16 mm) 1-20 ref ref ref ref ref ref ref ref 1.b Do. newly laid <1 0 0 -1 -2 -1 -1 -2 -2 2.a Asph. concr., dense, smooth (≤ 8-10 mm) 1-20 0 0 0 -1 0 0 -1 -1 2.b Do. newly laid <1 -1 -1 -1 -2 -1 -1 -2 -2 3.a Mastic asphalt (max 12-16 mm) 1-20 0 0 0 +1 0 0 +1 0 3.b Do. newly laid <1 0 0 0 +1 0 0 +1 0 4.a Mastic asphalt (max 8-10 mm) 1-20 -1 -1 0 -1 -1 -1 -1 -1 4.b Do. newly laid <1 -2 -1 0 -2 -2 -1 -2 -2 5. Chipped asphalt (BCS) ("hot rolled asph.") 0-20 +1 0 0 +2 +1 0 +2 +1 6.a Chip seal, single (Y1), max 16-20 mm 1-20 +1 0 0 +2 +1 0 +2 +1 6.b Do. newly laid <1 +2 +1 0 +3 +1 -1 +2 +1 7.a Chip seal, single (Y1), max 10-12 mm 1-20 0 0 0 0 0 0 0 0 7.b Do. newly laid <1 0 0 0 0 0 -1 0 0 8.a Chip seal, single (Y1), max 6-9 mm 1-20 0 0 0 -1 0 0 -1 0 8.b Do. newly laid <1 -1 0 0 -1 -1 -1 -1 -1 9.a Chip seal, double (Y2), max 16-20 mm 1-20 0 0 0 +1 0 -1 0 0 9.b Do. newly laid <1 +1 0 0 +1 0 -2 0 0 10.a Chip seal, double (Y2), max 10-12 mm 1-20 0 0 0 0 0 -1 0 -1 10.b Do. newly laid <1 0 0 0 0 -1 -2 0 -1 11.a Porous asph., max 14-16mm (≥20%voids) 3-7 0 0 0 -1 -1 -1 -1 -1 11.b Do. "medium aged" 1-2 -1 -1 0 -1 -1 -1 -1 -2 11.c Do. newly laid <1 -2 -2 -2 -2 -2 -3 -2 -3 12.a Porous asph., max 8-12 mm (≥20% voids) 3-7 0 0 0 -1 -1 -1 -2 -2 12.b Do. "medium aged" 1-2 -1 -1 -1 -2 -2 -2 -3 -3 12.c Do. newly laid <1 -3 -3 -3 -4 -4 -5 -5 -5 13. Cem. concr., dense, smooth ≤ 20-80 mm 0-40 +2 +1 +1 +2 +2 +2 +2 +2 14. Cem, concr., dense, smooth, ≤ 12-18 mm 0-40 +1 +1 +1 +2 +2 +2 +2 +2 15. Cem. concr., ground (grinding not worn) 0-5 -1 -1 -1 -2 -2 -2 -1 -1 16. Paving stones, cobble stones (older type) 0-90 +3 +3 +2 +5 +4 +3 +5 +4 17. Cement block pavement (interlocking) 0-20 0 0 0 0 0 0 0 0



Table 23 - Road categories in the Nord2000 model

Main category

Sub category Name

1a Asph. concr., dense, smooth (≤12-16 mm) 1 1b Asph. concr., dense, smooth (≤ 8-10 mm) 2a Mastic asphalt (SMA) (max 12-16 mm) 2 2b Mastic asphalt (SMA) (max 8-10 mm) 3a Chipped asphalt (BCS) ("hot rolled asph.") 3b Chip seal, single (Y1), max 16-20 mm 3c Chip seal, single (Y1), max 10-12 mm 3

3d Chip seal, single (Y1), max 6-9 mm 4a Chip seal, double (Y2), max 16-20 mm 4 4b Chip seal, double (Y2), max 10-12 mm 5a Porous asph., max 14-16 mm (>20 % voids) 5 5b Porous asph., max 8-12 mm (>20 % voids) 6a Cem. concr., dense, smooth max 20-80 mm 6b Cem. concr., dense, smooth, max 12-18 mm 6 6c Cem. concr., ground (grinding not worn)

7 Paving stones, cobble stones (older type) 8 Cement block pavement (interlocking)

5.3 European projects

5.3.1 Introduction This chapter reviews the recently completed or still ongoing European projects dealing with the road surface influence on traffic noise.

5.3.2 HARMONOISE HARMONOISE proposes rather detailed correction terms or formulae for the influence of the road surface on vehicle noise emission. Since the reference surface type must be one that is reasonably common in each member state, and states have different preferences and policies, it is impossible to define one and only one reference surface. Instead, it is proposed to define a “cluster” of reference surfaces having fairly similar noise characteristics as follows:

DAC 0/11, DAC 0/12, DAC 0/13, DAC 0/14, DAC 0/16 SMA 0/11, SMA 0/12, SMA 0/13, SMA 0/14, SMA 0/16

A “Golden reference” is defined within this reference cluster, which is the ideal reference surface on which the basic values of HARMONOISE are based. It is (basically) close to a DAC 0/13 or an SMA 0/13. Then, depending on the actual reference surface used in a particular country and in a particular situation, one may make small corrections that normalize the actually chosen reference surface to the “Golden reference”. See further another technical report within HARMONOISE, dealing specifically with this issue [31].



The HARMONOISE engineering method for predicting road traffic noise [39http://www.imagine-project.org/] gives the noise emission from vehicles on the standard reference at standard temperature. The correction for the road surface is given by the following formula in dB:

( )0,,

,,,,,, log atmatmmref

mimsurfimsurfimsurf TTK

vv

C −++= βα (8)

where: surf = road surface type m = vehicle category i = third-octave frequency band n° αsurf, m, i, βsurf, m i = road surface correction coefficients for m-vehicles and i-

frequency band vm = speed of m-vehicles vref, m = reference speed for m-vehicles K = temperature coefficient Tatm = air temperature Tatm, 0 = reference air temperature Some road surface correction coefficients are given in an appendix as tentative default values for the following surfaces:

• PA 6/16 • 2 layer PA • transversely brushed concrete • exposed aggregate concrete • SMA 0/6 • surface dressing 1/3 • paving stones • HRA 20 • block paving.

In addition, corrections are given for the ageing porous surfaces:

))016,025,0(1( 20 ttLLt −−∆=∆ (9)

where t ≤ 7 years, and for wetness (for light vehicles only):

)2000

log()110log( fYv

XL ffwet +=∆ (10)

where:



Xf, Yf = frequency dependent coefficients v = vehicles speed f = frequency

5.3.3 SILVIA SILVIA does not propose specific corrections; instead, that project has developed a comprehensive scheme for not only determining correction terms - like Croad for instance – but, more importantly, for labelling a specific surfacing technology and for subsequently contractually checking the conformity of production of that technology once applied on the road. The proposed classification system [33] identifies specific measurement procedures necessary for labelling the acoustic performance of a road surface. There are two possible labelling procedures: LABEL1 (preferred): Assessment based on SPB and CPX measurements; LABEL2: Assessment based on SPB measurements and measurements of intrinsic properties of the road surface, e.g. texture and sound absorption (plus mechanical impedance if relevant). Both noise labels are based on SPB, which has been chosen in SILVIA as the reference noise classification method because of its representativity. However, because of the practical constraints that make the SPB method generally unsuitable for conformity of production testing in the field (see Chapter 4), the labelling procedure includes associated measurements that will be used as substitutes to SPB in the COP procedure. The underlying assumption is that it is sufficient to use either CPX or the relevant intrinsic surface characteristics of a given material to guarantee the conformity of its noise performance in terms of SPB. For the purposes of assessing conformity-of-production (COP), surfaces with a noise LABEL1 certification are to be assessed using the CPX method, whereas surfaces with a noise LABEL2 certification are assessed according to the relevant measurement of the intrinsic properties of the surface used in deriving the noise label. Table 24 summarises the recommended method of assessment for noise labelling and Table 25 summarises the recommended method for assessing COP. “Rigid” surfaces are defined as normal asphalt and concrete, i.e. being much stiffer than tyres.

Table 24 - Recommended labelling system for assessing the acoustic performance of different types of road surfaces - Determining the noise label

Method of assessment for different road surfaces Dense Graded Open Graded Label ID

Rigid Rigid Elastic SPB SPB SPB LABEL1 CPX CPX CPX SPB SPB SPB LABEL2 Texture Texture Texture



Absorption Absorption Mechanical Impedance

Table 25 - Recommended labelling system for assessing the acoustic performance of different types of road surfaces - Assessing COP

Method of assessment for different road surfaces Dense Graded Open Graded Label ID

Rigid Rigid Elastic LABEL1 CPX CPX CPX

Texture Texture Texture Absorption Absorption LABEL2 Mechanical Impedance

5.3.4 EU WG 8 The classification proposed in Table 26 is apparently based on a mix of German and British data. It has been proposed in a report commissioned by the European Working Group 8 on traffic noise that was delivered to DG ENT in 2003 [71].

Table 26 – Correction terms in dB(A) proposed by EffNoise [120]. The reference surface is Asphalt Concrete 0/11 and the reference speed is 50 km/h.

Road surface type Light

vehicles Heavy

vehicles Porous asphalt twin layer, less than 3 years old -6.0 -4.5 Porous asphalt twin layer, 3-5 years old -4.0 -3.0 Porous asphalt 0/11, less than 3 years old -3.1 -3.7 Porous asphalt 0/11, 3-5 years old -2.0 -2.0 Porous asphalt 0/16, less than 3 years old -2.0 -3.0 Porous asphalt twin layer, more than 5 years old -2.0 -1.5 Porous asphalt 0/16, 3-5 years old -1.0 -1.5 Asphalt concrete 0/11 0.0 0.0 Stone mastic asphalt 0/11 0.0 -0.3 Porous asphalt 0/11, more than 5 years old 0.0 0.0 Porous asphalt 0/16, more than 5 years old 0.0 0.0 Cement concrete, burlap treated 1.0 1.2 Hot rolled asphalt 2.0 1.0 Asphalt concrete 0/16 2.0 0.0 Porous asphalt 0/8, less than 3 years old -5.8 -3.7 Even pavement stones 3.0 2.0 Grip-surface 1.3 0.4 Porous asphalt 0/8, more than 5 years old -0.4 0.0 Cement concrete, exposed aggregate 1.3 0.4 Cement concrete, longitudinally brushed 1.3 1.7 Porous asphalt 0/8, 3-5 years old -3.8 -2.0 Surface dressing 0/11 1.5 0.5 Uneven pavement stones 6.0 4.0 Gussasphalt 1.9 -0.3 Cement concrete, transversely brushed 3.7 2.1



5.3.5 ROTRANOMO The ROTRANOMO Project (“Road Traffic Noise Modelling”) has elaborated a tool to calculate road related noise emissions in order to meet future standards of the EU Noise Directive "Assessment and Management of Environmental Noise" [121]. The calculations actually take into account the road surface by means of the classification developed by WG 8 (Table 26).

5.3.6 EffNoise EffNoise is a “Service contract relating to the effectiveness of noise mitigation measures” carried out in cooperation with EU WG HSEA “Health and Socio-Economic Aspects”. Considering measures on the noise sources, they exhibit a classification identical to the one given in Table 26 [120].

5.3.7 EU WG-AEN Finally, the same classification again has been taken over by the European Commission Working Group on Assessment of Exposure to Noise [74].

5.3.8 SILENCE The European project SILENCE is also presently developing such a correction table in its Sub-Project F “Road Surfaces”, Work Package 4 “Noise classification” [86]. It is intended to be adapted to urban conditions, which means that the surface influence will also be considered for low-speed, low gear setting driving conditions.

5.3.9 SIRUUS The objectives of the SIRUUS project (“Silent Road for Urban and extra-Urban Use”) were to develop new solutions for low-noise surfaces capable of reducing traffic noise by 3 dB(A) on motorways and 5 dB(A) in urban areas. The reference surfaces were, respectively a “traditional porous asphalt type road surface” on motorways and a “traditional dense bitumen road surface” in urban areas. Three types of low-noise pavements were tested on an Italian motorway, among which two sophisticated, so-called “euphonic” and “ecotechnic” pavement structures and the already known two-layer porous asphalt. The publishable part of the otherwise confidential final technical report [123] claims that the objective has been met but does not tell with which solution.

5.4 Discussion Across countries, the names of the different surfacing materials and techniques are not always comparable or translatable. In the Dutch and Swiss tables (Tables 15, 16, 20), the surfacing types have been translated by us. In all other tables, the categories are as given in English in the source documents. The comparison is still more difficult when proprietary names are used. When the comparison seems possible, like between popular materials and technologies like DAC, PA, SMA, EACC for instance, the rankings are in



general poorly consistent as Table 27 shows. However, when there is a reference surface, it is consistently a dense asphalt concrete or a combination of DAC and some other common surface like in USA and in the HARMONOISE proposal. There is also a lack of comparability between different classifications due to the use of different measurement and evaluation methods. In that respect it is to be highlighted that CPX and SPB are not equivalent as the Austrian data shown in Table 7. See also [33]. Although, in some cases, the ranking is given for different speeds including low speeds, in general, it is not clear whether it also applies to urban conditions where not only low speeds but also low gear settings are used. In addition, when a ranking is given in terms of an index including a certain proportion of heavy vehicles like with SPBI or Leq, the ranking could obviously not be adapted to urban conditions.

Table 27 – Comparison between rankings of “popular” surfacing types. Differences are in dB(A).

Country Reference SMA-DAC PA-DAC EACC-DAC Remarks AT Table 6 -1 0 Light veh. 50 km/h AT Table 7 -3,4 / -1,4 -3,3 / -1,3 -2,0 / 0,0 SPBI AT Table 7 -3,7 / +0,3 -1,5 / -0,3 -2,8 / -1,0 LMA FR Tables 9&10 -3,9 All 0/10 mm. Light veh. 90 km/h FR Tables 9&10 -3,5 All 0/10 mm. Light veh. 50 km/h DE Table 11a 0 30-50 km/h DE Table 11b 0,0 -2,0 All 0/11 mm. > 60 km/h HU Table 12 +2,9 All 0/12 mm IT Table 13 -1,4 JP Formula 1 -2,7 All 0/13 mm. 50 km/h JP Formula 1 -3,6 All 0/13 mm. 90 km/h NL Table 15 -2,61 -0,07 / +1,42 Light veh. SI Table 17 -2 -3 SI Table 18 -2,1 -6,9 ES Table 19 -1 < 60 km/h ES Table 19 -3 > 80 km/h CH Table 20 0 -4 US Table 21 -1,55 Light veh. NO Table 22 0 / +1 -1 / 0 All max. 16 mm. Light veh. Among the factors that influence the precision of the classification, we can quote the variability of road surfacing materials mainly regarding texture depending on the characteristics of ingredients, laying circumstances, characteristics of traffic and climatic effects on ageing, etc. With those remarks in view, it is questionable whether the two decimals given in the Dutch and American tables (Tables 15, 16, 21) have any significance. Even the first decimal is probably not significant either, unless it is rounded to the closest half unit. Actually, nowhere is the precision stated except in the procedures proposed by SILVIA where tolerances are indicated on the Labelling and COP results (not reported here; see [33]).



Until the procedures proposed by SILVIA are applied routinely, a compilation of existing correction terms could be used as default values for comparable surfacing types. However, the classifications available so far are generally based on data collected several years ago. In the meantime, other technologies - like for instance thin layers - have become popular, often under proprietary names as in the Dutch classification (Tables 15 & 16), which can moreover be different across borders. So, there is a need for supplementing the tables in that respect. In addition, since urban conditions are probably not well represented by the available classifications, there is a need for extending the data base to urban conditions including low speeds and low gear settings. The main problem with classifying road surfaces regarding noise is the wide variability within a given category of materials. Figure 4 is a first classification attempt based of tyre/road noise measurements carried out with a car on several dozens of pavement “types” in Belgium in the late seventies. The fact is that the range of variation within a given type generally exceeds the average differences between types. Figure 5 is a more recent classification established in France and based on cars pass-by noise. Even though the categories are much more narrowly defined than in the Belgian study, the same conclusion can be drawn: it seems illusory to assign a “noisiness” level to a given surfacing type. The reason is likely that the acoustic performance of a road surface is not

Figure 4 – Early attempt to classify road surfaces in Belgium based on CPB levels of a car coasting at 80 km/h, engine off [79].

Porous asphalt

Resinous slurry

Asphalt concrete

Surface dressings

Cement concrete

Cobble stones

65 70 75 80 85 90dB(A)



Figure 5 – French classification based on cars passing by at 90 km/h [118]

only determined by its compound. There is a significant influence of the laying process and circumstances, which will determine the most noise-relevant surface characteristics i.e. macro- and megatexture. In addition, over time, wear due to weather and traffic - and clogging of porous layers - will also affect the noise performance to some extent. Finally, along any apparently homogeneous road section, the noise level – as measured by means of a CPX-type equipment – usually varies by some dB(A)’s. Comparison measurements reported by the Dutch IPG project [63] further demonstrate the variability of the initial noise performance in terms of SPB noise level reduction19 of the same type of pavement – actually a double-layer porous asphalt – laid by the same contractor and different contractors at different places. The differences within the set of surfaces built by the same contractor can be up to 2 dB(A) for cars (Figure 6) and more than 3 dB(A) for lorries (Figure 7). Only two contractors out of eight were able to reproduce the same pavement performance within a range of 1 dB(A) for both cars and lorries. The maximum differences between different contractors are also about 2 to 3 dB(A).

19 With respect to a reference level corresponding to a standard Dense Asphalt Concrete.



Figure 6 – Initial noise reductions in terms of SPB average pass-by level for light vehicles travelling at 110 km/h on different sections in double-layer porous

asphalt in Netherlands [63]. A to H are different contractors. A and B built a 2/6mm top layer. C to H built a 4/8mm top layer. Each contractor was requested to

reproduce the same pavement on four different motorways: A28, A30, A15 and A59.

Figure 7 - Initial noise reductions in terms of SPB average pass-by level for heavy vehicles travelling at 80 km/h on different sections in double-layer porous asphalt

in Netherlands [63]. A to H are different contractors. A and B built a 2/6mm top layer. C to H built a 4/8mm top layer. Each contractor was requested to reproduce

the same pavement on four different motorways: A28, A30, A15 and A59.



6 Conclusions and recommendations When noise classification of road surfaces are required for calculation purposes or as rough guidance to road authorities, i.e. when high precision is not required, we cannot see any other solution in the short run than to make the best use of existing data as those reported in Chapter 5. In the longer run, that kind of data will have to be more reliable and precise, namely for contractual purposes. To that end, we can but recommend concentrating on the validation at European level of a classification system such as the one developed by SILVIA. Basically, the concept is to associate a type approval procedure and conformity of production procedure. There is no type approval procedure for road surfaces that applies across the European Union. However, some countries are beginning to operate schemes that effectively act as type approval procedures for road surfaces. To our knowledge, the United Kingdom and the Netherlands are the only Member States having a regulation specifying noise performance for road surfaces and how to check them in situ. In the United Kingdom, the Highways Agency Products Approval (HAPAS) was developed primarily with the aim of assessing the fitness for purpose of different road surface products. New road surfaces have to comply with the requirements of HAPAS in order to achieve certification for use in road constructions and maintenance programs. In 1998, the scheme was extended to cover the type approval of proprietary thin surfacing materials, and it was decided at the time to include an optional noise test. The test procedure developed by TRL for this type approval largely follows the ISO SPB method, but uses three classes of vehicle instead of the two classes normally used. A similar scheme, known as the CRoad scheme, was introduced in the Netherlands in the late 1990s [89] to act as both a type approval scheme, based around the ISO SPB method, and for ensuring conformity of production, using CPX measurements. The procedures proposed by SILVIA are compatible with the Dutch system as they provide CRoad and the COP procedure accepts the use of CPX measurements. Indeed, the Dutch as well as the British systems essentially rely on CPX measurements to make the link between the type approval and the COP tests. However, it is not exaggerated to state that CPX can be considered as a makeshift. It has become very popular essentially because it is much more practical than CPB or SPB. But its representativity is highly questionable because: • it measures only tyre noise, other sources of vehicle noise that could be influenced by

the surface characteristics are not considered; • its representativity of truck tyre noise is doubtful until a CPX for truck tyres is

developed, which does not seem realistic; • it is poorly correlated with far-field measurements; • it is very sensitive to the exact location of the microphones because of the complex

radiation pattern around a tyre; • on porous surfaces, it does not take into account propagation effects;



• on porous surfaces, it does not take into account the possible absorption of power train noise.

Apart from the reference tyres issue, a big problem with CPX is the wide diversity of the already existing equipment, which explains the discrepancies between the measurement results when comparing different devices. Reproducibility problems have moreover been observed between devices that, in view of their similarity, could be assumed to deliver identical results. In an attempt to better secure the reproducibility between different variants of CPX equipment, the SILVIA project proposes a set of certification procedures that have been published in a booklet by the Gdansk Technical University [122] to ensure the conformity of a given device to the basic specifications of the ISO standard. SPB is the only truly representative method since it is actually measured at the road side, more or less at the position of the exposed façades. It takes into account the whole range of vehicle types and speeds, which makes it possible to derive the noise level of any real traffic. Therefore, it is flexible in the use of the results: it can be adapted to any kind of road (motorway, rural, urban) depending on the main relevant traffic characteristics (proportion of heavies, average speed). However, it is subject to constraints that prevents it to be used everywhere. It is not generally applicable in urban areas. Moreover, it tests only a spot on the road. Therefore, it is neither practical nor cost-effective for acceptance or COP tests since it would have to be repeated many times along the road section. That is why SILVIA has introduced the concept of auxiliary testing methods that could be used as “proxies” for CPX and SPB. This could work provided a robust model is available to convert the relevant characteristics (i.e. texture, absorption, stiffness) into noise levels or noise reduction levels or indices. Such models already exist. SILVIA has developed one, based both on statistical data and on computer simulations [33]. It still needs to include the stiffness influence. Let us finally point out that, in contracts, tolerances should be set at realistic values taking into account the intrinsic variability of the acoustic performance of road surfacing types, which can typically reach several dB(A)’s in terms of vehicle noise levels. Such tolerances are suggested in the SILVIA labelling and COP procedures. Summing up, here are our recommended next steps for setting up a European noise classification system for road surfaces: 1) Standardization:

1. A CEN standard for CPX equipment should be taken over from - or inspired by - the ISO draft and include the certification procedures developed by SILVIA or a reference to it.

2. The revised ISO standard for the SPB method should be taken over as a CEN standard as soon as it is issued.

3. The draft ISO standard for the determination of megatexture should be taken over as a CEN standard as soon as the ISO standard is issued.



4. The ISO standard for sound absorption measurement in situ using the extended surface method should be taken over as a CEN standard.

5. A CEN standard should be developed on how to characterize road surfacings with respect to noise as proposed by SILVIA. Part 1 would describe the labelling procedure and part 2 would describe the associated COP procedure. The first issue does not need to include stiffness.

6. Later on, a CEN standard should be developed on how to measure and evaluate the mechanical impedance of road surfaces in a way relevant to noise. It would then be referred to in the next issue of the labelling and COP standard.

2) Research and development:

7. Measurement methods for stiffness – more precisely: mechanical impedance – should be further developed and validated as really noise relevant, possibly building on the method proposed by SILVIA.

8. The model proposed by SILVIA relating the road surface influence on vehicle noise to texture, sound absorption and stiffness should be completed to include stiffness, and validated.

Those eight objectives can be pursued in parallel. Steps 1 to 5 don’t require much pre-normative work, if at all. One can found on SILVIA but further validation could prove useful. Therefore, those Member States that are not yet acquainted with the issue should be encouraged to put the procedures on trial in order for their representatives in a future CEN group to gain specific expertise and to possibly help improve the procedures. To that end, a project is currently being in negotiation stage with the Commission, namely “INQUEST – Information Network on Quiet European (road) Surfacing Technology”. It includes a series of workshops to disseminate the results of SILVIA in the countries that were not involved in SILVIA and setting up a European Group of Users. Steps 6 to 8 should start as soon as possible. The development of a standard on stiffness (step 6) will of course depend on the research results (steps 7 & 8). The necessary research must include further development of the technology of the PERS and full-scale experiments for testing the acoustic effectiveness and durability of different PERS solutions. This effort would take several years and would need strong support from the Commission. As such a research project similar in nature to SIRUUS (involving laboratory research on materials, preliminary tests on small-scale experimental sections and full-scale experimental road sections), let us take the SIRUUS budget as a first guess, i.e. 3.5 million € over 4 years.



7 References [1] Anonymous, “Adaptation and revision of the interim noise computation methods for the purpose of strategic noise mapping”. Two reports within the main title are of interest here, namely “Final draft report” and “Road Traffic Noise – Noise emission: databases”. Contract B4-3040/2001/329750/MAR/C1, European Commission, DG Environment, Brussels. [2] Anonymous, “Baudurchführung – Grundlagen – Prüfverfahren – Feldprüfungen – Rollgeräuschmessung”, RVS 11.066, Bauministerium für Wirschaftliche Angelegenheiten, Wien, April 1997. [3] Haider M., “Rollgeräuschmessung – Optimierung von erfahren und Grenzwerten”, Strassenforschung 3.277, Endbericht, Arsenal Research, Wien, 2004. [4] Anonymous, "Guide du Bruit des Transports Terrestres – Prévision des niveaux sonores". Ministère de l’Environnement et du Cadre de Vie/Ministère des Transports/CETUR, Novembre 1980. [5] Besnard F. et al., “The procedure for updating the vehicle noise emission values of the French « Guide du Bruit »”, EURONOISE, Naples, 2003. [6] Besnard F. et al., “The procedure for updating the vehicle noise emission values of the French « Guide du Bruit des Transports Terrestres»”, Ministère de l’Equipement, des Transports, du Logement, du Tourisme et de la Mer, Note Technique, Paris, Novembre 2002. [7] Anonymous, "Richtlinien für den Lärmschutz an Strassen (RLS-90)". Ausgabe 1990, Bundes-ministerium für Verkehr, Postfach 210360, 5000 Köln 21, Germany. [8] Anonymous, “Verfahren zur Messung der Geräuschemission von Strassenoberflächen (GEStrO-92)”, Anlage zum ARS 16/1992, Der Bundesminister für Verkehr, 1992. [9] Anonymous, “Decree on the content- and form-related requirements for strategic noise maps serving for the assessment and management of environmental noise as well as the calculation and investigation methods implemented for the preparation of strategic noise maps”, Hungarian Ministry of Environment and Water, Guidelines 25/2004 (XII.20). [10] http://pcangelo.eng.unipr.it [11] Tachibana, H., "Road traffic noise prediction model 'asj model 1998' proposed by the acoustical society of japan - part 1: Its structure and the flow of calculation". Proc. of INTER-NOISE 2000, Nice, France. [12] Oshino, Y.; Kono, S.; Ohnishi, H.; Sone, T.; Tachibana, H., "Road traffic noise prediction model 'ASJ Model 1998' proposed by the Acoustical Society of Japan - Part 2: Calculation model of sound power levels of road vehicles". Proc. of INTER-NOISE 2000, Nice, France. [13] Anonymous, “Reken- en meetvoorschrift verkeerslawaai”, Regeling als bedoelt in artikel 102, 1ste en 2de lid, van de Wet geluidhinder, Den Haag, Sdu, 1981. [14] Eijbersen et al. : « De methode Cwegdek 2002 voor wegverkeersgeluid », Publicatie 200, CROW, Ede (NL), April 2004. [15] http://www.stillerverkeer.nl [16] Anonymous, « Mode opératoire – mesure du bruit de contact pneu/route », CRR, Bruxelles, MF 50/84, 1984



[17] Bar P., Delanne Y., Réduire le bruit pneumatique/chaussée, Presses de l’ENPC, collection du LCPC, 1993. [18] Anonymous, Slovenian Official Gazette n°45:1995. [19] Anonymous, Slovenian Technical Specification TS 06.640:2003. [20] Ramsak M., Kokot D., Tušar M.: "Comparative study of traffic noise emission for characteristic types of asphalt mixtures in Slovenia", SIIV 2004, “New technologies and model tools for roads”, Firenze, 27-29 October 2004. [21] Anonymous, "Rehabilitación de Firmes", Norma 6.3 IC, Ministerio de Fomento, Dirección General de Carreteras, Madrid (Spain), December 2003. [22] Anonymous, « Instrucción para el Diseño de Firmes de la Red de Carreteras de Andalucía », Junta de Andalucía, Consejería de Obras Públicas y Transportes, Dirección General de Carreteras, Andalucía (Spain), 1999. [23] Alfèrez J.R., Echazaretta F. S., Mateos M.D.J. : « Elaboracion de mapas estrategicos de ruido de carreteras », RUTAS, Nov.-Dec. 2004. [24] Heutschi K., « SonRoad – Modèle de calcul du trafic routier », Cahier de l’Environnement n°366, OFEFP, Berne, 2004. [25] Anonymous, "Calculation of Road Traffic Noise", Dept. of Transport, Welsh Office, HMSO, London, U.K., 1988. [26] Phillips S., Kollamthodi S., Morgan P.A., “Classification of low noise road surfacings”, INTERNOISE 2001, The Hague, Netherlands, 27-30 August 2001. [27] Sandberg U., “Road Surface Categorization and Correction in HARMONOISE – Basic Considerations”, Final Technical Report, HAR11TR-030116-VTI05, 2003. [28] Anonymous, "Road Traffic Noise - Nordic Prediction Method (TemaNord)". Report 1996:525, Nordic Council of Ministers, Copenhagen, Denmark, 1996. [29] Sandberg U., "Korrigering i den nordiska trafikbullermodellen för inverkan av vägyta". VTI Meddelande 706, Swedish National Road and Transport Research Institute (VTI), Linköping, 1993. [30] Jonasson, H.G.; Storeheier, S.Å., "Nord 2000. New Nordic Prediction Method for Road Traffic Noise". SP Report 2001:10, Swedish National Testing and Research Institute (SP), Borås, Sweden, 2001. [31] Sandberg U., “Considerations with regard to reference surface in HARMONOISE”, Technical Report, HAR11TR-030715-VTI01, 2003. [32] Sandberg U., “Low-noise road surface classification and procurement system in Japan”, Private communication, 30/06/2005. [33] SILVIA, “Guidance manual for the implementation of low-noise road surfaces”, FEHRL Report 2006/02, Brussels (including an appended CD-ROM with complementary technical documents). [34] Anonymous, "Allgemeines Rundschreiben Straßenbau, ARS Nr. 14/1991", Der Bundesminister für Verkehr, 1991.



[35] Sandberg U., Ejsmont J., “Tyre/Road Noise Reference Book”, INFORMEX, Harg, SE-59040, Kisa, Sweden (2002). [36] ISO 13472-1:2002, “Acoustics -- Measurement of sound absorption properties of road surfaces in situ -- Part 1: Extended surface method”. [37] ISO 10534-2:1996 « Acoustics – Determination of sound absorption coefficient and impedance in impedance tube method – Part 2: Transfer function method » [38] ISO/CD 11819-2: 2000, “Acoustics -- Measurement of the influence of road surfaces on traffic noise -- Part 2: Close-proximity method”. [39] HARMONOISE, “Engineering method for road traffic and railway noise after validation and fine-tuning”, Technical Report HAR32TR-040922-DGMR20 (Deliverable D18), 20 January 2005 (http://www.imagine-project.org). [40] Beaumont J., Soulage D., Estimate procedure of vehicle noise on road surfaces - French/German procedure, International tyre/road noise conference, Gothenburg, SE, pp. 205-216, 8-10 August, 1990. [41] ISO 362:1981 « Acoustics – Measurement of noise emitted by accelerating road vehicles – Engineering method ». [42] ISO 7188:1985 «Acoustics – Measurement of noise emitted by passenger cars under conditions representative of urban driving». [43] ISO 11819-1:1997 «Acoustics – Method for measuring the influence of road surfaces on traffic noise – Part 1: Statistical Pass-By method». [44] Sandberg U., Noise trailers of the world – Tools for Tire/Road noise measurements with the close-proximity method, Noise-Con, Ypsilanti, USA, April 5-8, 1998. [45] Ejsmont J.A., Classification of road surfaces with respect to traffic noise by using the trailer method, Technical University Gdansk, Report No. 1992-01-09, 1992 [46] Springborn M., Reifengeräuschmessungen im Nahfeld und im Fernfeld zur Beurteilung der akustischen Eigenschaften von Fahrbahnen, Second international symposium on roads surface characteristics, Technische Universität, Berlin, pp. 20-33, 1992 [47] Caestecker C., Van Messem M., Proefvakken van geluidsarme cementbeton verhardingen, Infrastructuur in het leefmilieu, n° 1/97, 1997 [48] Sandberg U., Ejsmont J.A., Development of three methods for measurement of tyre/road noise emission: coast-by, trailer and laboratory drum, Noise control engineering journal, Vol. 23, n° 3, 1986 [49] ISO 10844:1994 – Acoustics – Specification of test tracks for the purpose of measuring noise emitted by road vehicles – Annex A: Measurement of pavement surface macrotexture using a volumetric patch technique. [50] CEN 13036-1:2001 “Road and airfield surface characteristics - Test methods - Part 1: Measurement of pavement surface macrotexture depth using a volumetric patch technique” [51] ISO 13473-1:1997 « Characterisation of pavement texture by use of surface profiles -–Part 1 : Determination of Mean Profile Depth » [52] ISO 13473-2:2002 “Characterization of pavement texture by use of surface profiles -- Part 2: Terminology and basic requirements related to pavement texture profile analysis”



[53] ISO 13473-3:2002 “Characterization of pavement texture by use of surface profiles -- Part 3: Specification and classification of profilometers” [54] Sandberg, U; Kalman, B; Nilsson, R: “Design Guidelines for Construction and Maintenance of Poroelastic Road Surfaces”, deliverable SILVIA-project n° SILVIA-VTI-005-02-WP4-141005 (2005) [55] http://www.harmonoise.org [56] ISO 10534-1:1996 « Acoustics – Determination of sound absorption coefficient and impedance in impedance tube method – Part 1: Method using standing wave ratio » [57] ISO 354:1985 (EN 20354:1993) «Acoustics – Measurement of sound absorption in a reverberant room» [58] von Meier A., Van Keulen W., System for measuring the absorption coefficient α in situ, M+P raadgevende ingenieurs b.v., Aalsmeer, MVM.94.1.1, 1995 [59] “La réduction du bruit aux abords des voies routières ». Recherche en matière de routes et de transports routiers, OCDE, 1995 [60] Morgan P.A., Watts G.R . “A novel approach to the acoustic characterisation of porous road surfaces”, Applied Acoustics, Volume 64, Number 12, December 2003 [61] Descornet G., Tyre/road noise generating mechanisms, noise/texture relationship, noise versus skid resistance, recent practical achievements in Belgium, ETH Mitteilung « Reifengeraeusch und Strassenbau », International Seminar, Zürich, nr. 57, 1984 [62] Kollamthodi S, Phillips S M and Balsom M H (2000). Factors affecting SPB measurements: Development of the backing board method. TRL Unpublished Project Report PR/SE/164/00. TRL Limited, Crowthorne, UK. [63] IPG Scientific Strategy Document, DWW-2005-70, November 2005. [64] http://www.euro.who.int/Noise. An extensive study about the adverse effects of noise on man is e.g. Berglund, B.; Lindvall, T. (ed.) “Community Noise”, Archives of the Center for Sensory Research, Vol. 2, Issue 1, Stockholm University and Karolinska Institute, Stockholm (1995), to be downloaded from http://www.nonoise.org/library/whonoise/whonoise.htm [65] EU Green Paper on future noise policy (1996), see http://europa.eu.int/en/record/green/gp9611/noisesum.htm [66] Anonymous. Updated Strategy Paper of the CALM Network, Oct. 2004. See http://www.calm-network.com [67] Babisch, W., “Transportation Noise and Cardiovascular Risk”, Review and Synthesis of Epidemiological Studies, Dose-effect Curve and Risk Estimation, WaBoLu-Hefte, Federal Environment Agency of Germany, January 2006 (downloadable from http://www.umweltbundesamt.de) [68] Anonymous. MIRA-T 2001 Milieu- en natuurrapport Vlaanderen: thema’s, Vlaamse Milieumaatschappij en Garant, Leuven/ Apeldoorn (2001) [69] Franssen EAM, Dongen JEF, Ruysbroek JMH, Vos H, Stellato RK, “Hinder door milieufactoren en de beoordeling van de leefomgeving in Nederland” (“Nuisance by environmental factors and the evaluation of the living environment in The Netherlands”), RIVM-report n° 815120001/2004, Dutch National Institute for Public Health and Environment, Bilthoven (2004)



[70] Bendtsen H, e.a., “Traffic management and noise reducing pavements - Recommendations on additional noise reducing measures”, SILVIA deliverable, doc. number SILVIA-DTF-DRI-008-11-WP5-020205-D12 Traffic Management, Danish Road Institute (2005) [71] Morgan PA, Nelson PM and Steven H, “Integrated assessment of noise reduction measures in the road transport sector”, Project Report, PR SE/652/03 ETD/FIF,20020051, TRL Limited/TÜV Fahrzeug GmbH, prepared for Enterprise DG, European Commission (2003) [72] Beckenbauer T. e.a., “Einfluss der Fahrbahntextur auf das Reifen-Fahrbahn-Geraüsch”, Forschungsbericht FE-Nr. 03-293/1995 MRB Bundesanstalt für Strassenwegen (Federal Highway Research Institute of Germany) [73] Sandberg, U, Descornet, G., “Road Surface Influence on Tire/Road Noise – Part I”, and Sandberg, U, Descornet, G., “Road Surface Influence on Tire/Road Noise – Part II”, Proc. of Internoise 80, Miami (1980) [74] Anonymous. “Good practice guide for strategic noise mapping and the production of associated data on noise exposure”, Position paper, European Commission WG-AEN, 13 January 2006. [75] Sandberg, U, “Vägytans inverkan på trafikbulleremissionen – korrektionstabel för effektsambandmodeller”, VTI Notat 30-2000, Swedish National Road and Transport Research Institute (VTI) Linköping, Sweden (2001), downloadable from http://www.vti.se/info/rapporter/edefault.asp [76] G. Descornet, “Efficiency in noise reduction of pervious coated macadam”, Road and Traffic 2000, International Road and Traffic Conference, Berlin, Vol. 5 (1988) [77] Sandberg, U, ”Semi-generic temperature corrections for tyre/road noise”, Proc. INTERNOISE 2004, Prague (2004) [78] Descornet, G. et al. “Traffic Noise and Road Surfaces: State of the Art”, SIRUUS-project, BRRC (2000) [79] Descornet, G, “Experimental study of the rolling noise of a test car on various existing road surfaces in Belgium”, Proceedings of the International Tire Noise Conference, STU-information No. 168-1980, NUTEK, Stockholm (1979) [80] Sommer, H, “Noise reducing concrete surfaces – State of the art 1992” In Heft 409, Strassenforschung, Bundesministerium für Wirtschaftliche Angelegenheiten, Vienna (1992) [81] http://www.italgrip.com (in Italian) [82] Sommer, H., „Herabsetzung des rollgeräusches bei betonfahrbahndecken“, Zement & Beton, n°3/90 (1990) [83] FEBELCEM, “Revêtements en béton silencieux”, Dossier n°18, Bruxelles, novembre 1998. [84] Spits, PL, “Open beton voor minder verkeersgeluid”, Cement, n° 3 (1990) [85] Anonymous. ”Optimalisatie van uitgeborsteld beton en bepaling van Cwegdek” (“Optimization of exposed aggregate cement concrete and dertermination of Croad”), report 03-09, CROW, Ede, the Netherlands (2003) [86] http://www.silence-ip.org



[87] Rao, S; Yu, H; Khazanovitch, L; Darter, MI, ”Longevity of Diamond-Grooved Concrete Pavements”, TRB paper 991220, 78th TRB meeting, Washington DC (1999) [88] “Richtlijn dunne asfaltdeklagen”, Vereniging tot Bevordering van Werken in Asfalt, Breukelen, the Netherlands (2004), see www.VBwasfalt.org [89] van Blokland, GJ; Kuijpers, A. “Type approval and COP tests for low noise road surfaces”. Proceedings of Inter-Noise 2001, The Hague, Netherlands 541-546. [90] prEN 13108:2005, “Bituminous mixtures — Material specifications — Part 2: Asphalt concrete for very thin layers” [91] Up to date information about thin layers can be found on the web site of the Dutch Noise Innovation Program: www.innovatieprogrammageluid.nl, especially in the “State of the Art Dunne Deklagen” and in the DRI-report “International Experiences with Thin Layer Pavements” (November 2005), which can be downloaded from this site. [92] Van Keulen, W, “Banden en wegdekken” (“Tires and Road surfaces”) HMB Lawaaibeheersing, (2003) [93] Brosseaud ,Y, Abadie R, Legonin R, “Couches de roulement très minces et ultra-minces en matériaux bitumineux à chaud. Bilan d’emploi et comportement», Bulletin de liaison des laboratories des Ponts et Chaussées, LCPC, pp. 55-71, n° 207 (1997) [94] Descornet, G, “Les enrobes drainants – Propriétés acoustiques”, Demi-journée d’étude CRR, Brussels (1988) [95] Delanne, Y, “Efficacité acoustique des enrobes drainants”, Revue Générale des Routes et Aérodromes, n° 653 (1988) [96] Legeay, V, “Macrotexture and low frequency tyre/road noise correlation”, International tyre/road noise conference, Gothenburg, Sweden (1990) [97] “State of the Art: Advies 2-laags ZOAB”, Dutch Noise Innovation Program, downloadable from www.innovatieprogrammageluid.nl. [98] Goubert, L; Hooghwerff, J; The, P; Hofman, R, “Two layer porous asphalt: an international survey in the frame of the Dutch Noise Innovation Program (IPG)”, Internoise 2005, Rio de Janeiro (2005), downloadable from www.innovatieprogrammageluid.nl [99] “State of the Art: akoestisch geoptimaliseerde wegdekken”, Dutch Noise Innovation Program, downloadable from www.innovatieprogrammageluid.nl [100] Kragh, J: „Traffic noise at two-layer porous asphalt – Øster Søgade, Year N° 6”, Danish Road Institute, Technical Note 30 (2005), downloadable from http://www.vejdirektoratet.dk/publikationer/VInot030/index.htm. [101] Goubert, L, “Two layer porous asphalt: an international survey”, Dutch Noise Innovation Program, Report Number IPG-RAP 04.00505 (2005) [102] Caestecker, C, “Test sections of noiseless cement concrete pavements”, Test report, Afdeling Wegen Vlaams-Brabant (Flemish Brabant Road Administration) (1996) [103] ”State of the art: Modieslab – Derde generatie stil wegdek (Third generation road surface)”, Dutch Noise Innovation Program (2005), downloadable from www.innovatieprogrammageluid.nl.



[104] Goubert, L, “Statistical Pass-By Vehicle Noise Measurements on Full Scale implementation on expressway test site and urban test site”, SIRUUS (Silent Road for Urban and Extra-Urban Use)-project (2002) [105] Donovan, PR, “Comparative Measurements of Tire/Pavement Noise in Europe and the United States”, the NITE-study, Illingworth & Rodkin, Inc., prepared for The California Department of Transportation (2005) [106] http://www.rubberizedasphalt.org/rac/racspecs/index.htm. [107] Commission Recommendation 2003/613/EC, Official Journal of the European Union n° OJ L 212/49, 22.08.2003 [108] Report from the Commission to the European Parliament and the Council, COM(2004)160, Brussels, 10.03.2004 [109] Directive 2001/43/EC of the European Parliament and of the Council of 27 June 2001 amending Council Directive 92/23/EEC relating to tyres for motor vehicles and their trailers and to their fitting, Official Journal of the European Union n° OJ L 211, 4.8.2001 [110] Bourbon, C.; Mummenthey R.D.; Noël, P. “Cartographie du bruit routier – L’expérience bruxelloise”, Rapport vulgarisé LIFE98 ENV/000/248, IBGE, Brussels, 2003 [111] ISO/CD 13472-2:2005 “Acoustics -- Measurement of sound absorption properties of road surfaces in situ -- Part 2: Spot method using a sealed tube”. [112] ISO/CD 13472-3:2005 “Acoustics -- Measurement of sound absorption properties of road surfaces in situ -- Part 3: Spot method for highly reflective surfaces”. [113] ISO/ TS 13473-4:2004 « Characterisation of pavement texture by use of surface profiles - Part 4 : Spectral analysis of surface profiles” [114] ISO/CD 13473-5:2005 (EN ISO 13473-5:2006) « Characterisation of pavement texture by use of surface profiles - Part 5: “Determination of megatexture” [115] ISO 13325:2003 “Tyres -- Coast-by methods for measurement of tyre-to-road sound emission” [116] European Environment Agency. Europe’s environment: The third assessment. EEA Environmental Assessment Report No. 10. EEA, Copenhagen, Denmark, 2003. [117] OCDE. Contre le bruit – Renforcer les politiques de lutte contre le bruit. OCDE, Paris, 1986. [118] Brosseaud, Ensais and Anfosso-Lédée. “Les revêtements de chaussées limitant le bruit de roulement – exemple de partenariat et de coopération entre l’administration et les entreprises françaises”, Conférence INFRA, Montréal, Canada-Québec, 26-28 novembre 2001. [119] Popp, C., Heidebrunn, C., Bonacker, M., Richard, J., Krapf, K.-G., Wetzel, E., Prall, U., Steven, H., Wende, H., EffNoise, “Service contract relating to the effectiveness of noise mitigation measures”, Final Report – Volume I, 2004 [120] Popp, C., Heidebrunn, C., Bonacker, M., Richard, J., Krapf, K.-G., Wetzel, E., Prall, U., Steven, H., Wende, H., EffNoise, “Service contract relating to the effectiveness of noise mitigation measures”, Final Report – Volume II (Annex 3), 2004 [121] Steven, H. “Presentation of Work Package 40 – Vehicle Noise Emission Model” at ROTRANOMO Workshop, Brussels, 17 November 2004 (www.rotranomo.com).



[122] Ejsmont, J.A., “Development of procedures for certifying noise testing equipement”, Gdansk University of Technology Publishers, Gdansk, 2005. [123] Luminari, M., SIRUUS, Final Technical report (Executive publishable summary), 27 June 2003.



8 Symbols and acronyms AC Asphalt Concrete ADT Average Daily Traffic AFNOR Association Française de Normalisation ASJ Acoustical Society of Japan CEN Comité Européen de Normalisation COP Conformity of Production CPB Controlled Pass-By (method) CPX Close Proximity (method) CPXI Close Proximity Index (derived from a CPX measurement) Croad Correction for the road surface influence (Dutch method) CRTN Calculation of Road Traffic Noise (UK method) Csurf Correction for the road surface influence (Austrian method) DAC Dense Asphalt Concrete dB(A) A-weighted decibel (unit of noise level) DLPAC Double-Layer Porous Asphalt Concrete DStrO Differenz / Strassenoberflache EACC Exposed Aggregate Cement Concrete EC Euopean Commission EU European Union GEStrO Geräuschemission von Strassenoberflächen HRA Hot Rolled Asphalt IPG Innovatie Programma Geluid ISO International Standardization Organization LAeq A-weighted equivalent sound level LAmax A-weighted peak noise level Leq Equivalent sound level LMA Lärmmessung Anhänger MLS Maximum Length Sequences (ISO 13472-1) MPD Mean Profile Depth (of surface macrotexture) MTD Mean Texture Depth (of surface macrotexture) NMS New Member State (in EU) OECD Organization for Economic Co-operation and Development PA Porous Asphalt PAC Porous Asphalt Concrete PCC Portland Cement Concrete (in USA) PERS Poro-Elastic Road Surface PSV Polished Stone Value RAC Rubberized Asphalt Concrete (in USA) RLS Richtlinien für den Lärmschutz an Strassen (Germany) RSI Road Surface Influence (term in calculations, UK) RVS Richtlinien und Vorschriften für den Strassenbau (Austria)



SD Surface Dressing SMA Stone Mastic Asphalt SPB Statistical Pass-By (Measurement method) SPBI Statistical Pass-By Index (derived from an SPB measurement) TAC Thin Asphalt Concrete TNM Traffic Noise Model (USA) VTAC Very Thin Asphalt Concrete WHO World Health Organization

Noise Classification Road Pavements (Technical) (1)

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