The National Road Noise Strategy incorporates a number of initiatives intended to reinforce road authorities' efforts to reduce noise from roads. The strategy will address the annoyance and health impacts of traffic noise taking into account efficacy and costs of noise mitigation measures.
National Road Noise Strategy
Since 2003, considerable efforts have been made with regard to national roads in particular. A promising development in noise-reducing asphalt and its widespread application is currently underway. Several municipalities have elaborated local noise mitigation plans.
The strategy places particular emphasis on helping municipalities in their efforts to reduce road noise. As nine out of ten homes affected by noise are situated along municipal roads, it is therefore the biggest challenge in the effort to reduce road noise.
Download the National Road Noise Strategy (2003) (PDF, 280KB)
Evaluation of the National Road Noise Strategy
The Road Noise Strategy was revised in 2010. The ensuing report summarised the ongoing efforts to mitigate noise since 2003 and government initiatives were updated accordingly.
The evaluation shows that most government initiatives have been implemented or are under positive development. However, the number of affected homes is still high, as 785,000 homes are affected by road noise above the recommended limit value – almost one of every three homes.
Download the revised National Road Noise Strategy (2010) (in Danish, with an English summary)
The Ministry of the Environment has supported five noise partnership demonstration projects. The funds were allocated to noise mitigation and distributed among the municipality, the Ministry of the Environment and affected citizens.
Danish Ministry of the Environment granted funds to five projects
In 2005, the Danish Ministry of the Environment set aside DKK 4 million for the creation of "financial noise abatement partnerships". These are joint projects by authorities and private citizens to finance noise mitigation. Five demonstration projects for noise abatement have been initiated in Allerød, Aarhus, Copenhagen and Frederiksberg (two projects).
Findings from the projects, in the years between 2005 and 2007, have been collected and published in a guide for noise abatement partnerships.
A guide to more easily establish partnerships
The aim of the guide is to simplify collaboration between municipalities and residents to finance noise mitigation measures.
The guide explains that residents in the five projects were willing to help pay the bill in return for a quieter environment. In total, residents paid approximately 40 percent of the DKK 13 million used on construction costs in the five projects.
500 residents in 250 homes found their house and quality of life had improved. The residents were motivated to help pay the costs as housing values would increase once noise levels were reduced. The demonstration projects show that potential rise in economic value is important, however, an improvement in the quality of life is just as equally important a motivation factor for many of the participants.
The partnerships are also an opportunity for the public to be involved in determining the means of noise mitigation.
The consequences of road traffic noise
In 2010, approximately 785,000 homes were affected by road traffic above the noise limit value. Approximately 90 percent of these homes were, and still are, located on municipal roads.
The National Road Noise Strategy (2003) showed that in socio-economic terms, noise mitigation is worth the cost, as it results in fewer annoyances and effects on health. The Road Noise Strategy estimated that 200-500 Danes suffer premature death as a result of exposure to road noise.
Read more about the Danish Road Noise Strategy below.
Socio-economic advantages of noise mitigation
The advantages of mitigating road traffic noise are significant and will have a better impact for the measures (noise screens, noise reduction glazing, noise-reducing asphalt, etc.), than the costs of mitigating noise. Incentives are therefore in place for both the responsible road authorities and people suffering from the effects of road traffic noise to support noise reduction schemes.
Houses and apartments increase in value as noise is reduced
In addition to the advantages from removing annoyances and protecting health, studies show that noise mitigation also leads to an economic benefit to property owners. Property values increase by just over 1 percent per decibel reduction for houses and approximately 0.5 percent per decibel reduction for apartments. Co-funding noise reduction can thus be seen as an investment for the property owner, as well as an increase in the quality of life.
The Nordic noise prediction method, Nord2000, was introduced by the Danish Environmental Protection Agency for strategic mapping of road and railway noise in 2006, and since July 2007 the method has been the prescribed calculation method for road and railway noise.
A joint Nordic prediction method
Nord2000 is a joint Nordic prediction method that was initially developed in 1996-2001 following an initiative from the Nordic Council of Ministers. It was intended to utilise the results of research and development that had taken place since the first joint Nordic methods were published in the 1970’s and early 80's.
The method includes source models for road and rail traffic in third octave bands from 25 Hz to 10 kHz. The propagation model can be applied for a variety of weather conditions, allowing a precise yearly average to be determined.
Complicated terrain is handled by a concise procedure, so the interpretation of terrain shapes by skilled personnel that earlier was necessary is now abandoned, and the method can be applied to automated noise mapping without loss of accuracy.
Use of Nord2000 in Denmark
In Denmark, weather statistics have been published for four weather classes (which are adequate for strategic noise mapping and general surveys). For detailed and precise calculations more specific calculations are necessary, and weather statistics for nine weather classes are published for this purpose.
In city centres, where the sound propagation is not free but influenced by repeated reflections and screening, only one weather class (neutral) is normally used.
Technical description, comparison with Harmonoise
The propagation model is based on geometrical ray theory, and the calculation of screening is based on geometrical theory of diffraction.* Refraction is modelled by using curved sound rays; the curvature depending on the sound speed profile and is determined by a semi-analytical approach.
The team responsible for Nord2000 took part in the European Harmonoise project, where the Nord2000 model formed a basis for the development of the Harmonoise Engineering model. Several of the findings from this project have been subsequently introduced in an update of Nord2000.
The benchmark cases used for validation of the Harmonoise model was also used for validation of Nord2000-road with a good result. It is expected that results obtained by use of Nord2000 are indistinguishable form results obtained by Harmonoise Engineering model. The Nord2000 propagation model has also been validated for high noise sources such as wind turbines.
The mandatory use of Nord2000 for strategic noise mapping is a consequence of the rules in Statutory Order no. 717 from 13 June 2006 . It also specifies most of the parameters to be used for the calculation (including the weather statistics, nine weather classes). Statutory Order no. 647 from 18 June 2007 specifies the corresponding statistics with four weather classes.
The Danish Environmental Protection Agency guidelines 4/2006 "Noise Mapping and Noise Action Plans" (in Danish) describes the use of Nord2000, mainly with a view to noise mapping.
In guidelines 4/2007 "Noise from Roads" (in Danish) Nord2000 is prescribed for general use with road traffic noise.
Simultaneously with this guideline, a supplement to guidelines 1/1997 "Noise and Vibration from Railways" was published, when Nord2000 was introduced for general use with railway noise.
All the technical publications are in English.
Download the manual for Nord2000-road (2006) (PDF, 685KB)
The background reports describe and specify the building blocks of the method;
A set of test cases has been elaborated for Nord2000 road. Corresponding test cases for railway noise focus on short distances, since the propagation corrections are identical.
Download Environmental Project no. 1335 from 2010 , for more information about the revised test cases for updated version of Nord2000-road.
Software implementing Nord2000
A few brands of noise mapping software has implemented Nord2000.
A program for approximate calculation of road traffic noise in a number of test cases can be downloaded for free at SINTEF .
* In order to handle non-flat and non-homogenous ground as well as multiple screens, screens with multiple edges, and propagation in an inhomogeneous atmosphere with vertical sound speed gradients, heuristic semi-analytical modifications have been introduced.
Several thousand homes are protected against noise with acoustic screening, and many more have been offered soundproofing grants, since Rail Net Denmark initiated its Noise Project together with the Danish Environmental Protection Agency.
"Preventive efforts in the planning and execution of the train operations cannot reduce the noise impact of the homes along the existing infrastructure. And that has necessitated an active effort to combat noise and provide noise protection," explains Lisette Mortensen, a noise coordinator from Rail Net Denmark.
Exposure to road noise may be linked to serious effects on health. Every year, several hundred people in Denmark are thought to suffer an early death as a result of exposure to road noise.
Health effects according to the World Health Organization
According to the World Health Organization (WHO), traffic noise may lead to annoyance and health effects, such as communication problems, headaches, sleep disturbance, stress, high blood pressure, an increased risk of heart disease and hormonal effects.
Noise can also affect productivity, children's learning and motivation. Thus, noise has a health impact on people and in the long term can lead to actual effects on health. Noise during the night, in particular, is thought to be harmful as it contributes to sleep difficulties, reduction in the quality of sleep, sleep disturbance and waking up earlier.
New WHO survey
A survey by the WHO in April 2011 concluded that one in three Europeans experiences annoyance from noise during daytime, whilst one in five experiences sleep disturbance due to traffic noise at night. The noise impact increases the risk of cardiovascular disease and high blood pressure.
The report concludes that traffic noise costs at least 1,000,000 healthy life years per year in Western Europe.
Health impact in Denmark due to traffic noise
In connection with the development of the Danish Road Noise Strategy in 2003, a first attempt was made to assess the scope of consequences on health.
A cautious estimate of between 800 and 2,200 persons in Denmark has been suggested as the annual number of hospital admittances for patients with raised blood pressure or heart disease as a result of the added risk posed by traffic noise.
It was also estimated that traffic noise is a factor in 200-500 premature deaths each year as a result of high blood pressure and heart disease.
New summary of health effects of road noise
Part of the Road Noise Strategy's evaluation in 2010 was a summary of health effects of road noise, carried out by the University of Stockholm. The evaluation confirms that there are serious health effects linked to exposure to traffic noise above the recommended limit values.
This also confirms that traffic noise causes sick days, and that several hundred members of the Danish population suffer premature death each year.
Download the summary of health effects of road noise (2009) (in Swedish) (PDF, 393KB)
A new Danish study shows link between noise and risk of stroke
A Danish study has shown that people living where traffic noise is very high have an increased risk of stroke, i.e. cerebral bleeding or blood clots.
The study used data from the Danish "Diet, Cancer and Health" study in which more than 57,000 people participated. The research team used addresses of cohort members from 1993 to 2006 and calculated the traffic noise for these addresses.
The number of people suffering from strokes in the cohort was registered for the period 1993-2006. The study took into consideration smoking habits, education, air pollution and other such variables with regard to the effects of noise.
Assuming the used data is correct, calculations show that 5 percent of strokes are due to traffic noise. This corresponds to approximately 600 new strokes in Denmark every year.