 |
|
–We put the porous pavement Whisperfalt on a part of Main Road E6 by Espa, about 100 km north of Oslo, as a measure for noise reduction, says Jostein Aksnes, NPRA, who is an expert on low noise pavements.
– The contractor Lemminkäinen introduced
this recipe in addition to three other low noise pavements which we tested. So
far we have conducted oise easurements
twice, which show that Whisperfalt produces less noise and has acceptable
wear resistance.
According to Aksnes noise from tyres can be reduced in two ways. One alternative
is asphalt with smooth and textured surface which lead to less tyre vibration and consequently less noise. The second alternative is porous asphalt with a continuous system of pores. Air being compressed under the wheel can thereby be displaced through this system of pores, which gives less pumping of air and thus less noise. The optimal low noise pavement combines both principles for noise reduction by the source, and this is what NPRA is trying to achieve with Whisperfalt.
Other positive qualities with porous pavements are better friction ratio and
reduced risk of aquaplaning. In addition,
current experiences from winter mainte- |
|
nance indicate less need for salting as the
grains of salt remain in the asphalt pores.
– Besides the ice breaks open more quickly, Aksnes adds.
Final measurement on the test pavements
at Espa will be conducted next summer.
– Then we will see which pavement is
the best both when it comes to noise reduction, condition and economy. So far
Whisperfalt has shown auspicious qualities
– when it is new it has very good noise
reducing charcteristics. But it is a little
more expensive than the other alternatives, and porous pavements have also to be cleansed so that the pores remain open, ends Aksnes and adds that low noise pavements are of use to everybody, not only for those who stay behind a noise deflection wall or inside a noise insulated house with the windows shut.
Henriette Erken Busterud and
Thorbjørn Chr. Risan, NPRA, Norway
Contact
Jostein Aksnes, NPRA |
