The quest for quieter road surfaces
Anything that has an internal combustion engine is, by default, rather noisy, as such roads in general tend to be a very noisy affair because of the large number of various engines on any stretch of road at any one time, however you may not realize that a lot of noise is also generated at ground level, meaning where the car meets the road.
Normal highway traffic generates somewhere between 65-75 decibels from a distance of fifteen to thirty meters – this is equal to the normal level of a conversation from about a meter away.
Considering the importance that roads and cars have in America, a few states and companies have been looking into ways of decreasing the noise level of the road surfaces.
The level of road noise is influenced by the road’s texture, stiffness and its porosity, and these are all features that pavement engineers are trying to alter. There is one technique which reduces noise by designing the road texture with small divots and gouges in it, however once these get clogged the sound reduction disappears.
This technology has been mandated by the European Union in large metropolitan ares, and in order to mitigate the issues of clogging, giant vacuum-cleaner-like devices are used to clear up the divots.
The states of Arizona, California and Virginia have been testing various types of road surfaces as part of this wish to reduce road noise with Washington State showing only limited success in its sampling of different experimental surfaces.
The problems with these new types of surfaces vary, from the fact the they are more expensive to lay down than traditional roads, they also require more repairs than the traditional roads and in some cases, the alternatives broke down to such an extent that they became noisier than the original pavement.
Despite the somewhat mixed results that Washington State has seen, they plan on continuing studying the issue and experimenting with different pavement surfaces.
