The research projects ASTRA 2004/006-007 and ASTRA 2005/006 started a comprehensive investigation of "low-noise road pavements in low speed area" in 2003. It included the realisation of pilot stretches with the corresponding technical and acoustic tests. 12 pavement types were identified and were incorporated as test stretches. In addition 9 existing low-noise pavements were included into the investigation.
The positive insights of the research projects ASTRA 2004/006-007 and ASTRA 2005/006 moved the federal bureaus FEDRO and FOEN to start a research package to the subject of "low-noise road pavements in urban areas" and to guarantee therefore continuity in the treatment of this important question. The works are subdivided into 4 part projects:
- TP1: Research and innovation
- TP2: Test and validation
- TP3: Long-term Monitoring
- TP4: Impulse program (is not integrated in the research package. Results and apprenticeships out of TP2 can deliver valuable references to the construction and for the conversion of TP4).
The GPL-LAB leads the TP1 and 2 in arrangement with the FEDRO in "fiduciary" sense. The GPL-LAB guaranties the coordination with the TP3.
The TP3 and TP4 are led through the FOEN and are accompanied by the FEDRO.
The positive insights of the older research projects from FEDRO moved the federal bureaus (FEDRO, FOEN) to start a research package to the subject of "low-noise road pavements in urban areas" and to guarantee therefore continuity in the treatment of this important question.
The project has thus the following aims:
- Push the further development in "low-noise road pavements in urban areas".
- Promote the acceptance of low-noise road pavements and reach with the street owners a Win-Win-situation
In an initial phase, the following steps are taken:
- Implementation of the definition of the project organisation. This includes in particular the occupation of part of the project lines TP1 and TP2.
- Preparation of the sub-projects with the creation of the corresponding concepts.
- Definition, approval, tendering and contract awards of individual research projects.
- Definition of new test tracks, as validation of the recommendations from the first project.
After the initial phase an interim report will be drawn, which serves as input for the second phase. It includes new or complementary research activities as well as other test tracks for the validation of the research from the initialisation.
The conclusion of this work is a synthesis report of all activities (research and validation), including recommendations for further work.
The project brings the following findings regarding noise-reducing effects in the new situation:
- The acoustic effect of SDA 4 coverings is on average between about -4.5 and -8 dB (A) for cars and between about -5.5 and -8.5 dB (A) for trucks. Thus, the acoustic quality of the SDA varied 4 coverings by up to 3.5 dB (A).
- The two realized SDA 6 coverings are with an acoustic quality of about -6.5 to -6 dB (A) seen for cars and approximately -6.5 and -4 dB (A) for trucks acoustically in the SDA 4 coverings.
- The acoustic effect of the SDA 8 coverings is on average between about -0.5 and -5 dB (A) for cars and between about -4 and -7 dB (A) for trucks. Thus, the acoustic quality of the SDA 8 varies coverings by up to 4.5 dB (A).
- The acoustic effect of the SDA coverings considered depending on the cavity class, notice that deposits with higher void content classes generally perform better as coverings with a void content of less than 12% with the same maximum grain.
Change the noise reducing effect since installation. Moved with most coverings the decrease in the acoustic effect within the expected range, similar to that even in dense standard road surfaces is observed. In line with the general trend slowed the decrease in the acoustic effect in the second year after installation. An atypical and above-average decrease in the acoustic effect the coverings in Yverdon, Näfels and Visp on. How to develop the deposits with increasing age, must future measurements show.
Acoustic demands on the layer thickness. An optimum noise reduction effect sound absorption caused by substantial sound absorption characteristics in the medium frequency range (800 to 1250 Hz) in which, when tire-road noises most acoustic energy arises. Are significant sound absorption characteristics in the medium frequency range when there is sufficient void content typically only achieved from layer thicknesses of 30 mm and more.
Method used to collect the water permeability / porosity. With that in present research project used methods may due to small pore diameters any statements about the porosity of 4 mm coverings are made. Experiments were carried out with an adapted method by which instead of water a soap solution was used. This was expected to - thanks to the lower surface tension the soap solution to obtain measurable values. Unfortunately with the adjusted method no valid measured values are determined.
Alteration of the surface on the test pad in Visp. C
Noise protection regulations Article 11 regarding road owners oblagation for maintenance of roads was developed.