Overview
The construction of porous asphalt pavements experienced a recent technological development in Switzerland, in Germany and in Austria. The advantages of this type of pavement lie primarily in the disappearance of the aquaplaning risk and the noise reduction. However, certain disadvantages are raised like the reduced lifespan of these materials in comparison with traditional pavements, as well as the winter maintenance which can be difficult sometimes.
The aim of this project is to describe state of the art of the developments and the experiments relating to porous asphalt in Switzerland, Germany and Austria. With the initiative of the road Directors within the CEDR of the sectoral research programs are engaged among several countries sharing the same concern.
It is proposed to establish an inventory of the porous asphalt pavements existing in these three countries. With this intention, a very complete questionnaire was made and was distributed to the regional road administrations. The data thus collected could be analysed and evaluated. A report will make the critical synopsis of the collected results. The bases for a possible international research program will be thus established.
The methodology of the project is as follows:
- bibliographic research
- surveys through a questionnaire
Funding
Results
The use of porous asphalt surface courses is particularly motivated because of the great noise reduction potential of this kind of surface layer apart from the drainage effect. But experiences in Austria, Germany and Switzerland also showed the negative effects of using porous asphalt surface courses, as for instance problems in winter maintenance procedures (modified winter maintenance, increased salt consumption, de-icing, etc.) or the inferior long-term behaviour compared with conventional asphalt pavements.
In the context of this research project (D-A-CH, cooperative project Germany – Austria – Switzerland) porous asphalt surfaces have been examined regarding to their structural and functional durability, i.e. the lastingness of the noise-reducing effect and the drainage effect. With the help of a questionnaire experiences gained in Austria, Germany and Switzerland have been collected, updated and analysed.
In general, the answers of the questionnaire show similar experiences with this type of surface layer throughout the three countries. As positive effects the noise reduction potential and possible advancements in traffic safety because of the increased drainage ability were mentioned by the respondents. The most negative effects have been declared because of modified winter maintenance techniques, possible clogging of the pores, and, as a result of this, a reduced noise reduction behaviour and shorter structural lifetime compared to dense asphalt surface layers.
As consequence of the analysis of the questionnaire the project consortium advises to do more research solving the main problems regarding porous asphalt surfaces:
• Road safety,
• Structural lifetime and
• Acoustical lifetime.
Particularly it would be necessary and useful to accomplish more measurements and accompanying observations regarding the surface condition as well as the noise emissions within a certain time span to enhance our knowledge about the long-time performance of porous asphalt surface courses.