In 2022, a French newspaper had a headline declaring that a “miracle asphalt” was developed in Paris.
The majority of environmental noise emissions in European cities is due to road infrastructure. One of the major targets of the EU’s Environmental Noise Directive (END) is therefore to reduce this source of noise by 2 decibels. But there is a problem: it is said that, with the advent of electric vehicles, it is impossible to innovate cars further to be less noisy; it is difficult to get less noise from the engine of vehicles. This is a reality that cities who need to reach the target of the END.
In Paris, they have turned attention to the friction between tires and pavement – what is called “rolling noise”. Two solutions have been tested. The first is to reduce speed limits on roads. The slower cars move, the less noise. The other is to innovate pavement. They could make pavement that is less noisy. This is done by altering its materiality and consistency. For instance, by making the pavement more porous. A porous structure limits the sounds emitted as tires pass over the road. The problem is that the more porous the pavement is the less structural stability it retains; it more easily breaks down; and the more costly it becomes because it needs to be maintained and replaced. In 2022, the City of Paris tested three types of pavements in a project called Cool & Low Noise Asphalt (or “CLOWN”). Each of which had different levels of porosity. The outcome: they found two types of pavements that will be used, one for roads with speed limits of 50 km/h and another for a road with speed limits of 30 km/h. The former is called SMAphon, and the latter Bphon+.
As a city official told me, these will be the new pavements in Paris. Its streets will be paved with many more tiny holes. The city will become more porous. But less noisy.