Project shows impact of road noise on vehicle design
A research project at Renault has demonstrated that the condition of roads leads to acoustic problems that restrict the range of electric vehicles.
The APACHE (Appraisal of Pavement Acoustic CHaracteristics and Energy Efficiency) programme monitors road noise to produce maps of the acoustic condition of the road network.
Renault has been using noise cancellation to address the problem in vehicles. This is activated by sound sensors placed around the vehicle, which listen to the road and detect variations in road noise. When this increases, the sensors inject a sound wave into the cabin which evens out the sound spectrum in the vehicle, cancelling out the noise heard by passengers and making the journey on board far more pleasant.
“The problem of noise in the environment isn’t just a question of which car, which tires? It’s about how the car interacts with its environment,” said Thomas Antoine, Expert Leader Noise & Vibration Technology at Renault. “The Apache technology not only improves the acoustics inside our vehicles, but also enables local authorities to make more accurate decisions about their road repair budgets. So, in fact, it’s a win-win situation for everyone,” said Antoine.
It was while studying noise cancellation sensors that Antoine wondered whether it wouldn’t be possible to use the signals they generate in a different way. Apache analyses the road data to give a very precise analysis of where a road is in particularly bad condition and therefore noisy.
To produce more comprehensive maps, Thomas called on Fadila Hrird, a work-study geomatics student who joined Renault Group as part of her masters program at the University of Cergy in France.
She uses a specific program to create maps with various layers of information, such as proximity to sensitive locations (schools, hospitals, retirement homes, etc.) to determine the level of impact a road may have on local residents.
“We get a tremendous amount of data from these sensors, but then it’s a question of transforming it into useful information. For these maps to be correlated with road use, we need to know how often the roads are used, and that’s where our partnership with Bruitparif comes in very handy,” said Hrird.
However one essential element was missing: road use. This data is crucial in determining the speed at which a road deteriorates, and the extent to which it generates noise pollution.
Antoine contacted Bruitparif, the Noise Observatory for the Île de France region, which was looking for more information on the acoustic condition of roadways. Bruitparif provided data for a test programme in the Saint-Quentin en Yvelines area that has now been extended to the whole of the Île de France region.
This uses thirty vehicles equipped with the Apache casing criss-crossing the region’s roads to measure the condition of the roads.
Thomas and Fadila’s in-depth analyses have confirmed that there is a direct link between noise and range for electric vehicles.
The Apache programme is able to put a precise figure on the costs and environmental savings associated with road repairs, and even in how many days the cost of road repairs is offset by a fall in emissions.
Bruitparif has calculated that 1 euro invested in roads represents 17 to 20 euros saved on the social cost of noise. To give a concrete example, refurbishing the Paris ring road, the busiest road in Europe, would divide noise levels by around four, and become a carbon neutral project within 3.5 years by saving 16,000 tonnes of CO2 per year.
Fadila Hrird is now looking at AI applications to process an ever-increasing quantity of data, which will make projects such as Apache even more relevant.
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