According to a CEREMA study, cars emit more CO2 when driving at 30 km / h. Discover the explanations.
If you follow the news, and especially if you live in the Paris region, you are probably aware that the maximum speed is lowered to 30 km/h in the entirety of intramural Paris, from this Monday. According to Anne Hidalgo, at the origin of this measure, this new limitation should make it possible to reduce air pollution, as well as noise, while the effects of jolts linked to acceleration and deceleration would be lessened. But this lowering is also part of a larger project, that of reducing the place of the automobile in the capital, this one being considered too polluting according to the city council, as well as his assistant to transport, David Belliard. The elected EELV had indeed affirmed not long ago that ” the challenge is to reduce the space of the car, which means reducing speed ”. This therefore has the merit of being very clear. As of today, therefore, the whole capital is going at 30 km / h, except for certain axes such as the Champs-Elysées, the streets of the Bois de Boulogne and Vincennes as well as the avenue Foch, among others, which remain at 50 km / h.
=> Find out all you need to know about the 30 km / h limit
But will this lowering of the maximum speed in Paris have a real impact on polluting emissions? Nothing is less certain, and this measure could even be counterproductive. A conclusion to say the least surprising, which emanates from the very serious Cerema, an organization placed under the supervision of the Ministry of Ecological Transition. He then just published the results of his major investigation into the limitation to 30 km / h, which had been the subject of a citizen consultation a few months before its implementation on Monday, August 30. And the conclusion is final, the organization emphasizing that “ for light vehicles as for heavy goods vehicles, emissions are significant at very low speed (up to approximately 30 km / h), which means that road traffic congestion situations are very penalizing from the point of view of air quality “. An announcement which should therefore undermine the theory defended by Anne Hidalgo and her team …
What ideal speed?
According to the Cerma report, a car traveling at 30 km / h would emit on average 18.9% more CO2 than when driving at 50 km / h. But it is when driving at even lower speeds that vehicles would pollute the most, with passenger cars emitting an average of 0.65 g of NOx per kilometer, against around 40 grams at 70 km / h. Moreover, according to the Cerema report, it is at this speed that the vehicles would be the most “clean”, since they would then reject less fine particles, carbon dioxide and nitrogen oxides. However, these results remain to be qualified, while the organization stated in a study published in 2013 that “ these curves are unsuitable for evaluating the impact of zones 30. Indeed, the installation of a zone 30 does not presuppose that the average speed practiced before was of the order of 50 km / h (top speed that the it is only reached when the flow of traffic is fluid and there is a sufficiently long section, without bends, without retarding device and without crossroads, intersections being the elements that punctuate the path of vehicles) ».
If elected officials hope that this measure will reduce the place of the automobile, it should not in fact change much. Indeed, the average speed in Paris does not generally exceed 15 km / h.
Also read on Auto-Moto.com:
30 km / h in Paris: what you need to know
Paris at 30 km / h: where can we still drive at 50 km / h? – OFFICIAL CARD
Paris: how the new resident parking works