Begrænsning af trafikstøj
2. English Summary
In January 1997, the Danish Environmental Protection Agency and the Danish Ministry of Transport formed a joint venture in order to co-ordinate a follow-up of the objectives made for noise in the report "Traffic 2005". One of the aims in this report, is that no more than 50,000 dwellings should be affected by noise levels above 65 dB(A) in 2010.
To implement the project, a steering committee with members from the Danish Environmental Protection Agency (DEPA) and the Danish Ministry of Transport, the Danish Road Directorate, the Danish National Railway Agency and DEPA's Reference Laboratory for Noise Measurements (DELTA) was appointed. COWI has assisted with analyses and as secretary to the committee.
The purpose of the project is to identify and assess the effects of a range of possibilities to fulfil the objectives in Traffic 2005.
The project included a study tour to Germany and the Netherlands to evaluate new opportunities of reducing noise at close hand. The results achieved in the Netherlands with low-noise road pavement known as 2-layer self draining porous asphalt are particularly interesting.
As a starting point, various measures have been identified and selected for further analysis of the traffic noise problems. Hereafter, the noise and economic effects of each solution are evaluated. The analysis concerns primarily the effects of dwellings affected by levels higher than 65 dB(A), as these are pointed out as the main interest.
The selected measures are as follows:
- Phaseout of the high noisy tyres in use,
- Replacement of relevant road surfaces using today's technology on low-noise pavement;
- Replacement of relevant road surfaces using the latest technology in noise reduction;
- Lower speed in urban areas;
- Noise barriers;
- Extra sound insulation of buildings;
- Redirection of traffic to main roads without noise sensitive buildings.
The effect of the selected measures is calculated and compared to a so-called reference showing the development of the number of dwellings affected by noise levels up to and above 65 dB(A) in 2010. The reference calculation is based on the assumptions of future growth in traffic and the effects of the latest EU regulations on vehicle emission.
It should be pointed out that the effect of traffic growth projections is rather simplified as it is presumed that traffic growth occurs equally throughout all road types. A more precise projection can be made as soon as an estimate of the dispersion of traffic growth by different road types is available. Furthermore, effects depend on the EU regulations passed until 1996.
The analyses show that a lot of effort is necessary , including a continuation of the current initiatives, to achieve the aims on noise reduction. Many of the evaluated possibilities have relatively large potential, although the effectiveness is depending upon how they are implemented politically.
The calculated effects of the selected measures are shown below[2]
The separate effect on dwellings with noise levels higher than 65 dB compared with the reference.
The calculations are based on the assumptions that the efforts to replace the noisiest tyres will reduce the noise 1 dB on local urban roads and main urban roads, and 2 dB on motorways and dual carriageways. Calculations show that despite low effects in this field, relatively noticeable results can be accomplished. This would require political initiatives, followed up by further developments and a change of priorities for the tyre characteristics at the tyre and car manufacturers. The noise will be reduced at the source, and the results will be apparent shortly afterwards. No decisions have been made as to how such an improvement could be reached, but an analysis of how the different types of tyres are applied, would be necessary in order to attain a better estimate of the reduction of noise levels.
On the basis of the experience accomplished in the Netherlands of using 2-layer self draining porous asphalt, a provisional estimate has been made as to the effects and cost of replacing relevant road surfaces in Denmark. As shown in the diagram, calculations using these assumptions give noticeable results. Furthermore, it is economically favourable using this solution instead of the other analysed measures. Further research as to how the technology can be adaptable to Danish conditions will be necessary to be able to estimate the economic and noise reductions.
Calculations show that a solution using the replacement of road surfaces with 1-layer self draining porous asphalt, is less effective for dwellings affected by noise level above 65 dB(A). This is due to the fact that there are only a few highly affected dwellings at the main roads where this solution is applicable. Despite this, these particular dwellings will achieve good noise reductions at comparatively low costs. Furthermore, the solution would have relatively large effects on dwellings affected by noise between levels 55-65 dB(A), see a more detailed description below.
Lower speed in town areas is a solution applicable to both noise and safety considerations. If speed is reduced through legislation or by using traffic signs, some sort of control will be necessary, otherwise there will be no achieved effect. The use of additional speed-reducing measures such as "bumps" and other special surfaces should be chosen carefully as other noise problems may arise.
Noise barriers and sound insulation are well-known as effective noise reduction measures. None of these solutions reduce noise at its source, however, and are relatively expensive in comparison to their effectiveness. Design of noise barriers must also be considered aesthetically.
Sound insulation is effective with regard to reducing noise levels inside dwellings, but not in the neighbouring environment. The use of improved sound insulation of dwellings and noise barriers are still considered as important factors in noise reduction, as the time-scale for the use of other solutions are somewhat longer. Apart from this, there will still be a need for solving acute noise problems for the most affected parts of the population.
As regards redirecting the traffic into larger roads, the calculations show that its effect rely strongly upon the assumptions, and will furthermore be affected considerably by the local conditions. There is, therefore, a need to explore, how the results are dependant upon local conditions with relation to the redirected traffic.
The calculations mainly focus on dwellings affected by noise levels of 65 dB(A) and above. Apart from this, all the solutions, with the exception of sound insulation, are also effective for dwellings with lower noise levels. In order to illustrate this correlation, the results of noise reduction calculations using various solutions for dwellings affected by noise levels in the range 55-65 dB(A) are shown in the annexe. Relatively large effects are achieved for dwellings affected by noise in the range 55-65 dB(A) with surfaces comprising of 1-layer self draining porous asphalt, extensive use of noise barriers and redirecting traffic to larger roads. The effect on dwellings with noise impact between 55 and 65 dB for these solutions compared to dwellings in the noise range of 65 dB(A) is three times higher. By using the remaining solutions, the effect on dwellings with noise impact between 55 and 65 dB is approximately twice as good as on dwellings with noise impact above 65 dB.
In addition to the analysed solutions, there are a number of other possible solutions for noise abatement. The possibilities are for example, additional strengthening of EU emission regulations, increases in transport taxes in order to reduce traffic growth or to create a move towards low-noise transport and preventative measures through better area, building and infrastructure planning along with better information and better driving instruction on low noise driving techniques.
[2]Sound insulation is not included as the effects of sound insulation apply only to inside individual dwellings; numbers of dwellings with reduced inside noise levels are apparent.