1.10 - Noise

Version 2

    Introduction


    Noise still tops the public nuisance charts and is the leading complaint of city dwellers living alongside streets and highways. Other than building noise barriers, creating vegetation buffer zones, protected zones, the use of noise absorbing road surfaces, and beyond traffic management measures, controlling behavioral pollution, it is possible to abate the noise emitted by vehicles.

    Important progress has already been made in this field such as soundproofing or even encapsulating thermal engines, acoustic improvements of exhaust systems and reduced tire rolling noise. 

    The massive introduction of electric vehicles will almost completely eliminate engine noise. This will have an important impact in towns where speeds are generally lower and there are numerous accelerations.

     

    Noise and health


    Though the impact of noise has long been underestimated, world health and environmental authorities now recognize it as a source of pollution in its own right, with negative effects that have been extensively studied. For example, in 2011 the World Health Organization (WHO) published the results of a study assessing the impact of environmental noise on human health in Western Europe. This analysis quantified the consequences of noise pollution in terms of disability-adjusted life-years lost: cardiovascular disease (61,000 disability-adjusted life years lost per year), cognitive impairment (45,000 years), sleep disturbance (903,000 years), tinnitus (22,000 years)... In Europe noise thus represents the second cause of death from environmental risk factors, after atmospheric pollution. 

     

    Noise and regulations


    Recognition of the danger of environmental noise has led many countries to assess the most exposed zones and populations. In Île-de-France (Paris metropolitan region), the Regional Council created a noise observation unit (Bruitparif) in 2004 to develop a regional map of noise pollution and to prioritize noise protection measures and modifications to be made. These kinds of local initiatives are often conducted in the context of national or transnational regulations. In the European Union, the framework of the fight against noise pollution was laid out in a 2002 directive that has been widely translated into national law. The directive calls for the development of noise maps and related action plans related to land and air transportation in particular.

     

    In the field of motor vehicle noise, regulations are even more specific and restrictive. Within the European Union, several directives have progressively reduced the acceptable noise level for motor vehicles, depending on vehicle type and power. And in February 2013, the European Parliament adopted a bill to reduce this noise limit even further by 2019. The limit will go from 74 to 68 decibels for standard cars.

     

    Noise and technologies


    Along with these strengthened regulations, new technologies, road infrastructure renovations, and cooperation among all the key stakeholders in the field of automotive transportation have been critical in reducing traffic noise pollution levels. The noise produced by a motor vehicle is a complex phenomenon resulting from a number of factors: engine and tire quality, chassis stability, aerodynamics, car speed, road condition, driver behavior, weather conditions, etc. Slight variations in any of these parameters can produce totally different sound levels and frequencies.

     

    The most effective noise abatement solutions are thus often the most overarching. They are not only innovative in regards to a particular aspect (exhaust pipe, fuel injectors), but also address the interaction between all or part of the instruments that play in the car’s “concert”: engine and car body, car body and tires, tires and road surface, road surface and noise screens, noise screens and landscape, etc.  Though it is impossible to integrate all traffic parameters at a given moment, joint research and experiments conducted by several key players (car and car parts manufacturers, public work companies, planners, public authorities, etc.) generally produce the best results.  Indeed, there are a variety of ways to reduce car noise. 

     

    Sources of noise and noise reduction mechanisms for light vehicles

     

    Car speed

    Dominant source of noise

    Main means of action

     

     

     

    Less than 30 km/h

     

     

     

    Powertrain noise

    Engine soundproofing

    Optimization of the vehicle's vibro-acoustic effects

    Continued improvement of exhaust systems

    Development of electric and hybrid models

    Eco-friendly driving

     

     

     

     

     

    Between 30 and 50 km/h

     

     

     

     

    Tire/road contact noise (rolling noise) and powertrain noise

    Development of quiet tires

    Development of absorbent road surfaces

    Installation of noise screens and anti-noise equipment

    Engine soundproofing

    Optimization of the vehicle's vibro-acoustic effects

    Continued improvement of exhaust systems

    Development of electric and hybrid models

    Eco-friendly driving

     

     

    Above 50 km/h

     

    Tire/road contact noise (rolling noise)

    Development of quiet tires

    Development of absorbent road surfaces

    Installation of noise screens and anti-noise equipment

    Source: Bruitparif