Paris continues to test its noise and heat resistant asphalt. Co-financed by the European Union, the City of Paris and its partners, the public works companies Colas and Eurovia, and Bruitparif are continuing their program Life cool & Low noise Asphalt », launched in 2018.
This Friday, Dan Lert, Deputy to Anne Hidalgo in charge of ecological transition, the climate plan, water and energy, and Jeanne d’Hauteserre, mayor of the 8th arrondissement, were on one of the pilot sites of the project, rue de Courcelles, to take stock, four years after the installation of the new coating.
The noise felt by the inhabitants divided by two
“The feedback from local residents is very good, comments the borough mayor, they are asking for a little more calm in this busy street with heavy traffic. Since 2019, the new test surface has been installed over 200 meters between the entrance to Parc Monceau and the Pagoda Paris.
Called BBPhon+, this new skin, developed by the Colas research and development laboratory, seems to be proving its worth since evaluations show a 3 decibel reduction in traffic noise compared to a normal skin. “It’s the equivalent of a reduction by two of the noise felt by the inhabitants of housing that overlooks the street,” explains Dan Lert.
“Noise is captured directly at the source,” explains Philippe Barrière, R&D engineer at Colas. The noise generated by the tire on the road is attenuated either by the porosity of the coating which captures the sound, or by the roughness of the road, which will fight against the impact aspects of the tire. »
The bitumen collides with the cobblestones
Faced with the success of this test, Jeanne d’Hauteserre, like the local residents, wishes to extend the surfacing to the street. But several obstacles stand in the way of such an initiative. The first, sinews of war, is the cost of operations. The tests in twenty streets of Paris, on 80,000 m2 of road, cost 2.5 million euros and are largely financed by Europe. Overall, such a coating costs between 2 and 8% more than a conventional mix, according to Dan Lert.
But above all, as is the case in the rue de Courcelles, you have to work to remove the cobblestones. An additional charge, but above all a loss for Parisian heritage, according to the Commission du Vieux Paris. “We understand the historical aspect and the attachment to cobblestones. But they were installed at a time when people traveled on horseback and with carriages, argues Jeanne d’Hauteserre. Today, the traffic is no longer the same, especially since the 30 km/h limit, supposed to limit the noise level, is not respected. »
More heat improvements
Another obstacle comes from the coating itself. Intended to reduce urban heat islands by its characteristics, the newcomer has not yet fully proven itself. One degree less observed around the test area. It’s positive, but below the 3 degrees initially targeted.
The Colas R&D team is still working on this project: “It’s very complex to measure in a real situation. We have launched laboratory tests to try to quantify it. But we have not yet demonstrated the significant advantage of using clear aggregates in terms of thermal comfort”, explains the Colas team, who is considering aggregates that would whiten the surface with wear, thus making it possible to retain less heat.
“It’s a public health problem, testifies Dan Lert, we know that the heat in summer causes significant sleep problems. We are heading towards periods of twenty days of heat waves per year, which will transform the climate of Paris and make it similar to that of cities like Seville. »