Abstract
Traffic noise is one of the main sources of noise pollution in cities. Around an 80% of the city noise is produced by vehicles. One of the current technological challenges is to achieve a sustainable acoustic environment in constantly growing cities with a rising quantity of vehicles. Current legislation obliges to determine the noise level of a vehicle according to a test procedure shown in Directive 70/157/EEC.
The maximum noise level allowed by de Directive has been declining gradually; however, this reduction has not affected the overall traffic noise. One of the reasons is that the approval test does not represent properly the real noise level emitted by a real car in real driving conditions.
In this work, a sample of vehicles has been instrumented to obtain physical measurements of the variables that can influence on the noise emission level. Vehicle positions, vehicle speed, longitudinal accelerations and drive time have been analyzed using a GPS sensor. Engine speed, engine load, throttle position and gear shift position have been studied through the vehicle CAN BUS and a battery of microphones has measured emitted noise in several points of the vehicle.
A circuit that represents the usual circulation in a big city like Madrid has been defined and several vehicle models with great presence in existing fleet of cars have been selected. Several drivers have covered the circuit at different times of the day and previous parameters have been measured in each test in order to determine average values of behavior.
To conclude, previous data have been analyzed and noise equivalent levels have been identified with different test configurations. With these average values, it has been possible to define the noise emissions produced by a vehicle in real driving conditions and to identify the noisier driving style.
A noisy driver produces up to 9 dB (A) more on average than others. Depending on the engine type a vehicle can emit about 5 dB more of engine noise for the same driving style. There is no appreciable influence of the driver experience over the considered driving interest parameters. There is no influence of the driver sex over the considered driving interest parameters.
Nowadays there are not studies about the influence on global acoustic contamination due to a vehicle as individual source neither about the influence of driving style.
KEYWORDS: Vehicle Noise, Passenger Car, Urban Traffic, Drive Style, Noise Pollution