Roadway noise

With road traffic noise (even short road noise ) the total noise generated by road traffic is called. This was mainly the noise generated by cars and trucks and motorized two-wheelers and rail tracks are to be expected. Sound is created, inter alia, by rolling noise of tires, rail wheels, wind noise (air resistance), engines, exhaust systems and acoustic signals. A lesser role is played by the construction noise from construction vehicles and construction equipment. Road traffic noise is in the industrialized countries by far the strongest source of noise pollution.

5.1 noise prevention 5.1.1 Regulations for the transport planners
5.1.2 Regulations for the vehicle operator
5.1.3 Regulations for the vehicle manufacturer

7.1 Procedure at the emission
7.2 Measures on propagation
7.3 Procedure at the immission

Physical Basics

Noise is produced either directly by air turbulence or the impingement of a turbulent air on surfaces ( aeroacoustics ) or indirectly via structure-borne noise in vibration excited bodies, whose surfaces radiate the sound in the environment. Pressure fluctuations in the air, which result for example from road traffic noise will be heard by the human ear. In order to thereby indicate the strength of the sound, the so-called sound pressure level in dB ( A) is determined at the immission.

However, the sound pressure level is not a measure that describes the perception of sound events. For example, noise from rail vehicles with equal mean sound pressure levels are significantly quieter perceived by the residents as sounds of car or truck. This is called railway bonus .. Hence psychoacoustic relationships in the assessment of road traffic noise are taken into account.

Characteristics

For understanding and assessment of road traffic noise, knowledge of rules for evaluation of sound pressure levels is essential. The sound pressure level is a logarithmic size, it is therefore necessary to observe special calculation rules. The following parameters of the sound perception can be identified:

A doubling of sound power (eg two identical sound sources instead of one ) causes an increase of the noise level by 3 dB (A). This means the traffic volume should double that leads to a sound pressure level increase of 3 dB ( A).
In order to be raised or lowered to cause a doubling of the volume or volume halving of the noise level by about 10 dB (A).
Is doubled, the distance to the sound source, it has a sound pressure level reduction of 6 dB (A) resulted. Conversely, that in a halving of the distance to the sound source with an increase of 6 dB (A ) can be expected. This applies to point sources, such as individual vehicles. Busy streets can be viewed as a line of sound sources on the other hand; here results in halving or doubling the distance a level difference of 3 dB ( A) or -3 dB ( A).
At increasing distances from the sound source weathering effects such as wind, humidity and temperature distribution have a big impact on the sound pressure level. So this may vary at a distance of 200 m by up to 20 dB ( A).
Reiner truck traffic causes at 100 km / h speed limit a sound pressure level increase of about 10 dB ( A) compared with pure car traffic. This value is dependent on the maximum authorized speed.

Pathogenesis of

Drive noise

Drive noises caused by the operation of the engine, transmission and drive train of a motor vehicle and their ancillaries and attachments. In the engine noise by combustion pressures, pressure fluctuations in the intake and exhaust system and mechanical forces in the valve and crank mechanism are generated. In electric drives they are created by electromagnetic forces in the camps and by switching operations.

Drive noises are transmitted as airborne and structure borne sound into the vehicle interior and the outside and dominate - depending on vehicle category and drive - at low speeds and high engine performance, such as in city traffic or during starting.

Tire-road noise

Due to the roughness of the road surface and the tire tread, the tread blocks and the carcass are vibrated and emit airborne sound. In addition, air is in the tire contact area displaced in the inlet and sucked back in the outlet. This gives rise to aerodynamic noise (so-called Airpumping ). Tire-road noise is over a wide speed range (from about 30-50 km / h, depending on the gear selection ) dominant. Particularly strong they occur natural stone paving with a rough surface and wide joints as well as trucks in appearance. For cars, the introduction of radial tires ( steel-belted tires), which are more durable and safer, but also much louder than bias tires, increases the noise level dramatically since the fifties, to a lesser extent, the ever-increasing trend toward wider tires.

Aerodynamic noise

At high speeds occur on the body and attachments noise generating air turbulence. Their investigation takes place in aeroacoustic wind tunnels. At highway speeds, and "quiet" tire-road combinations, the aerodynamic noise sources may clearly dominate.

Other noises

Acoustic signals such as horns, bells, sirens and the like are necessary to ensure the traffic safety. Therefore you can not be completely avoided. Furthermore, noise caused by audio reproduction systems or by the slamming of doors and hoods.

Factors

Number of vehicles ( traffic volume )
Type of vehicle ( truck, car, motorcycle)
Construction of the power train ( engine with gasoline or diesel engine, turbocharger, special equipment)
Soil structure ( ground vibration, acoustic emission line in the building)
Road surface ( cobblestone, whispering )
Driving speed ( the sound intensity of the tire-road noise increases with the power of the 3rd-4th speed, the aerodynamic noise at about the 6th power )
Mileage and age of vehicles (wear, corrosion)
Driving
Body type ( aeroacoustics )
Wheel load
Tire tread, tire building, tire pressure, tire width
Reflecting roadside development ( acoustic trough, standing waves, vegetation)

For sound technical forecasts ( planning of new roads as well as mitigation measures ), the radiated noise from a road (emission level) can be based on some of the above parameters (in particular, traffic density, percentage of trucks, maximum speed limit, road surface ) calculated. The "Guidelines for Noise protection at roads RLS -90" to be used in Germany. By means of a calculation of sound propagation, in which enters the distance of the immission from sound source, the emission limit to the nächstgelegenenen buildings can be so determined. With the help of special computer programs, extensive noise maps created and the effectiveness of different noise models can be checked.

Statutory regulations

Noise prevention

In the generation of traffic noise can be directly or indirectly involved three source categories call:

Vehicle manufacturers,
The motor vehicle operators and
Traffic planners.

The legislature addressed in separate legislation in each of these three groups.

Regulations for the transport planners

To protect the citizens against road traffic noise, the legislator writes in the case of new construction or substantial modification ( other lanes) of roads in the 16th BlmSchV limits for exposure to traffic noise to an area or a point of an area, the immission ago. Ambient air quality standards are defined in terms of a particular safety objective, the prevention of harassment or disturbance of sleep. For transportation planning, this means that will take into account in advance in the preparation or development of roads, how after the construction project is the noise pollution for local residents. When exceeding a given impact thresholds corresponding structural noise abatement measures must be taken during the planning phase.

The noise level at the immission is described by the rating level. The calculation method for determining the rating level is always applied when a new building or a significant change of roads is planned.

First, the average sound level L m, T ( 25) (day, 6:00 to 22:00 ) and L m, N ( 25) ( night, 22:00 to 6:00 ) is determined. As a basis for that is the authoritative hourly traffic volume M and the authoritative truck percentage p ( over 2.8 t permissible total weight ) as a percentage of total traffic. If there are no suitable sizes for this project-specific test results taking into account the traffic performance during the forecast period, this from the average daily traffic volume (DTV ) can be determined (with the help of a diagram included in the calculation specifications ). The average sound level then refers to an immission in 2.25 m height and 25 m distance from the road center of a single-lane road. For two-lane roads a substitute sound source is assumed in the center of the outer lanes to simplify the calculation procedure. Based on this average level of assessment level for a particular immission ( a house near the planned road ) determined with the following correction values

DV for correction of 100 km / h maximum speed limit different
DStrO correction for different road surfaces
DSTG correction for climb and descent,
Ds level change by different vertical distances s between the road and the relevant immission
DBM level change by soil and meteorology damping
DB level changes due to topographic conditions, structural measures and reflections ( noise barriers and walls, screens, etc.)
K supplement for increased interference effect of light- controlled intersections sign

The calculated rating level is then compared to the applicable limit. If it exceeds this, measures to lower the rating level must be taken.

Requirements for the vehicle operator

Rules on the use of vehicles in road traffic includes the traffic regulations ( Highway Code ). Here is the motor vehicle operator, the driver should be addressed. The Highway Code provides for measures for reasons of noise protection, if necessary to protect the public. The list of measures includes traffic prohibitions and restrictions, traffic diversions and speed limits. Traffic prohibitions or restrictions for certain types of traffic can be limited in space and time. An example is night driving restrictions for trucks.

Requirements for the vehicle manufacturer

Road vehicles only receive a general operating permit (ABE) and can thus be admitted to the road when their noise emission does not exceed certain noise limits. Since motor vehicles do not contribute in a uniform manner for noise generation in traffic, are required by law for different classes of vehicles have different emission limits.

( Road Traffic Licensing Regulations ) first regulations concerning the permissible noise levels of motor vehicles adopted under the Road Traffic Licensing Regulations already in 1937. Article 1 of § 49, said that " motor vehicles and their trailers ... quality such as to [ have ] that the noise level does not exceed the inevitable according to the state of the art measure". § 49 contained at the same time the policy for the noise measurement. Over time, this provision has been further developed, and with the Directive of 1966, standardized by the ISO measurement methods of accelerated passing, ISO R 362 was finally adopted.

With the Treaty establishing the European Economic Community, the European Community may also rules about the nature of the asset vehicle, also above the permissible noise issue with the predominant purpose of the Harmonization of Business Law and the elimination of trade barriers. The Council Directive of 6 February 1970 on the approximation of the laws of Member States relating to the type approval of motor vehicles and their trailers ( 70/156/EEC ) represents the Framework Directive, the basis of which technical requirements for the type-approval can be provided by cars. By the EC Directive was adopted in 1966 with slight variations as to EC Directive 70/157/EEC. After a period of optional use by national or Community legislation, Directive was adopted from 1 May 1981 for new types and from 1 October 1983 for the first time coming in the traffic vehicles mandatory in national law. According to § 49 of Road Traffic Licensing Regulations must motor vehicles, for the rules on the permissible sound level in the EC Directives 70/157 EEC, 74/151 EEC and 78/1015 EEC of the European Community are set to comply with those regulations. Thus, the EC directives have become part of the traffic regulations.

These directives were revised several times over the course of time and reduces the prescribed limits.

In June 2001, also the EU Directive 2001/43/EC was adopted relating to tires for motor vehicles and their trailers. Here is the detailed description of the method of measurement of noise emitted by the tire is not only fixed, but also limits sound pressure sound level when roles. For the measurements, a well-defined road surface is prescribed. The tests are carried out at speeds of 80 km / h for passenger cars and 70 km / h for trucks. However, measurements show that already at the entry into force of the Directive, all commercially available tires meet the limits or well below. A reduction in limits is therefore discussed.

Noise abatement

Through the EU Environmental Noise Directive, implemented in the German Federal Pollution Control Act with the version of 29 June 2005, the states are obliged to coverage for all major roads - these are roads with more than 3 million vehicles per year or approximately 8300 vehicles a day - and for all with more than 100,000 inhabitants to create noise maps cities. Measures that affect the correction values and are published in so-called action plans, should a noise reduction can be achieved ( noise barriers or speed limits ).

Noise abatement Switzerland

Homeowners who are affected by excessive noise can submit by applicable law from 2015 claims for compensation if the values of the Noise Ordinance are not met. The federal government expects to noise complaints in the amount of up to 14 billion Swiss francs in the road. An alternative would provide the lifting action of the authority and its replacement by annual recurring compensation payments.

Population burden of road traffic noise

In 16 Traffic Noise Ordinance ambient air quality standards are (short IGW ) set, which may protect the population in the new construction or substantial upgrading of roads are not exceeded (currently in residential areas 49 dB (A) at night and 59 dB ( A) during the day). Calculating valid for the day limit, for example, the width of the corridor in which for a typical highway in Germany, these limits are exceeded according to the guidelines for noise protection on roads ( RLS -90), we obtain for flat terrain with level the same road for a sound propagation in 10 m height a minimum of about 1500 m ( 100,000 vehicles per day, 25 percent of truck percentage, 130 km / h ). At night, the time required to comply with the limits swath width is due to the lower limit value is even much higher. Even for a country road with a traffic density of 10,000 vehicles per day arise at night after all necessary swath width of about 250 m (10 percent truck percentage, 100 km / h ).

Even the comparison of these figures with the reality shows that a large proportion of people living near highways must live with a noise exposure above the legal limits. Overall, about 30 percent of the total population in Germany were exposed to rating levels above the limit after 16 BlmSchV and about 50 percent levels above the guidance value according to DIN 18005 (which is set to something lower level), according to the Federal Environment Agency in 1999. Different polls in recent years resulted in unison that feel disturbed 2/3 of the population in Germany by road traffic noise approx. This value is much higher than the corresponding results for rail and air traffic.

Road traffic noise can affect health. Although he usually leads not cause permanent physical damage to hearing, averaging levels above 60 dB ( A) (daytime) but to a marked, above 65 dB ( A) even lead to findings among other things the Federal Environmental Agency in Berlin and the World Health Organization to significant increase in heart attack risk.

The effects of noise include, in particular on urban main roads also sociologically and economically relevant Deklassierungsprozesse that are subsumed under the heading of noise ghetto. The road noise abatement is therefore also a question of social justice.

Reduction of road traffic noise

Measures at the emission

Source of noise exposure (so-called emission source ) is the road in connection with the traffic that is handled on it. Structural measures such as the installation of porous asphalt layers ( commonly known as whispering ), include the active noise control. For a 560 m long construction phase of the federal highway 17 in Augsburg, a reduction of the calculated proportion of residents with increased risk of myocardial infarction from eleven to one percent over conventional asphalt concrete could be achieved by such a measure in 2003.

To reduce the sound pressure level speed restrictions or bans on certain types of vehicles can be set up. ( In about 80 percent of highways in town -level area speed limits already exist between 60 and 120 km / h )

Lowers level also acts to reduce the traffic volume. A halving of the amount of traffic leads to a reduction of sound pressure level by 3 dB (A). This reduction is precisely in the realm of perception threshold of the human ear. Only a reduction in the amount of traffic on one-tenth leading to a reduction of sound pressure level of 10 dB ( A) and thus to a halving of the loudness.

Behavioral influence opportunities are avoiding high engine speeds and racing starts and excessive volume of audio playback systems. This is especially true for otherwise relatively low-noise areas.

Further possibilities of noise reduction are the use of quieter drives, aero-acoustically optimized vehicles. This topic is dealt vehicle acoustics during vehicle development within the subject area. The possibility of noise abatement is the construction of quieter or even zero-emission vehicles. In the very quiet electric cars, however, new threats are already eg for pedestrians expected, which, inter alia, geared to the vehicle noise.

Measures the propagation

To reduce the propagation of sound, there are a variety of structural possibilities, which are also attributed to the active noise control (not to be confused with the term " active noise reduction" in the technical acoustics, which is usually associated with anti-noise measures).

Among the best known of these measures is the establishment of a noise barrier or a noise barrier. The latter requires much more floor space than the wall, but offers opportunities for planting. Noise barriers act mainly in that they interrupt the direct sound propagation to the receiver, whereby the shortest sound path leads over the top. Increased shadowing as light can be achieved only at high frequencies, the wavelengths are at low frequencies in the order of the height of the wall, whereby diffraction effects. Directly behind a high noise protection wall street noise, therefore, is not only quieter but also significantly low frequency. Noise barriers should therefore be carried out by the acoustic point of view, as high as possible, but this often meets with opposition because of the optical effect. More acoustic advantages are achieved by absorbing surfaces, as hereby additionally sound reflection can be prevented on the other side of the street.

In addition to noise barriers or noise barriers are in many places so called Wall wall combinations to find. Structurally far more complex, the lowering of the roadway is below the ground level (street down position). In this case, large amounts of earth have to be moved and it is to be expected with a higher surface areas. The most far-reaching solutions are the construction of an enclosure or a road tunnel. Such measures are very costly and also often require a permanent groundwater conservation.

Measures at the immission

At least far are satisfactory measures to reduce noise at the immission. This approach is also referred to as a passive noise. In this case, the installation of soundproof windows or additional sound insulation of building walls is carried out, but the measures are far less effective than the above-mentioned active noise reduction.

Psychoacoustics

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