Roadway noise is the most prevalent form of environmental noise. Pictured: São Paulo, Brazil.

Roadway noise is the collective sound energy emanating from motor vehicles. In the USA it contributes more to environmental noise exposure^[1] than any other noise source, and is constituted chiefly of engine, tire, aerodynamic and braking elements. ImageMetadata File history File links Download high resolution version (819x614, 168 KB) Summary A picture of rush hour in Prestes Maia expressway, in São Paulo, Brazil, taken by myself from a viaduct. ... ImageMetadata File history File links Download high resolution version (819x614, 168 KB) Summary A picture of rush hour in Prestes Maia expressway, in São Paulo, Brazil, taken by myself from a viaduct. ... Noise pollution, usually called environmental noise in technical venues, is displeasing human or machine created sound that disrupts the environment. ... This article or section does not cite its references or sources. ... An engine is something that produces some effect from a given input. ... A tire or tyre (see spelling differences and etymological origins) is a device covering the circumference of a wheel. ... Aerodynamics is a branch of fluid dynamics concerned with the study of gas flows, first analysed by George Cayley in the 1800s. ...

History

Roadway noise began to be measured in a widespread manner in the 1960s, when computer modeling of this phenomenon was perfected. After passage of the National Environmental Policy Act and Noise Control Act^[2], the demand for detailed analysis soared, and decision makers began to look to acoustical scientists for answers regarding the planning of new roadways and the design of noise mitigation. A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ... The National Environmental Policy Act (or, NEPA) was signed into law on January 1, 1970 by US President Richard Nixon. ... The Noise Pollution and Abatement Act of 1972 (or Noise Control Act of 1972, 92-574, 86 Stat. ... Roadway noise is the most pervasive form of environmental noise Noise mitigation is a set of strategies to reduce unwanted environmental sound. ...

Description of basic variables

The intensity of roadway noise is governed by the following variables: traffic operations (speed, truck mix, age of vehicle fleet), roadway surface type, tire types, roadway geometrics, terrain, micrometeorology and the geometry of area structures. Nighttime traffic captured by a camera over several seconds. ... The driver of this DAF tractor with an auto-transport semi-trailer truck prepares to offload Å koda Octavia cars in Cardiff, Wales A truck or lorry is a motor vehicle for transporting goods. ... The Trikke is a Human Powered Vehicle (HPV) This article is about the means of transport. ...

Traffic operations noise is affected significantly by vehicle speeds, since sound energy roughly doubles for each increment of ten miles an hour in vehicle velocity; an exception to this rule occurs at very low speeds where braking and acceleration noise dominate over aerodynamic noise. Small reductions in vehicle noise occurred in the 1970s as states and provinces enforced unmuffled vehicle ordinances. The vehicle fleet noise has not changed very much over the last three decades; however, if the trend in hybrid vehicle use continues, substantial noise reduction will occur, especially in the regime of traffic flow below 35 miles per hour. As a pedestrian safety issue, hybrid vehicles are so quiet at low speeds that the customary warning noise may not alert the pedestrian to nearby danger, creating a potential hazard for visually-impaired people, who rely on such noise to navigate in areas of heavy traffic. Trucks contribute a disproportionate amount of noise not only because of their large engines, but also the height of the diesel stack and the aerodynamic drag. Significant interior noise is usually present inside moving motor vehicles; in fact, passengers are generally not aware that these levels are high, because experience has led motorists to expect levels commonly exceeding 65 dBA. For the common automotive term of hybrid vehicle see: Petroleum electric hybrid vehicle A hybrid vehicle (HV) is a vehicle that uses two or more distinct power sources such as: An on-board rechargeable energy storage system (RESS) and a fueled power source for vehicle propulsion Human powered bicycle with... DBA may mean: // Decibels audible Diamond-Blackfan anemia Dibenzylideneacetone .dba format, a calendar format for Palm Desktop Doctor of Business Administration, an academic doctoral degree dba, a low-cost German airline The Dallas Bar Association for lawyers in Texas, USA A database administrator (or analyst) A-weighted decibels (dBA), in...

Sound level meter used in measuring noise

Roadway surface types contribute differential noise effects of up to 4 dB, with chip seal type and grooved roads being the loudest and concrete surfaces without spacers being the quietest. Asphaltic surfaces are about average. Image File history File linksMetadata Download high resolution version (439x1024, 42 KB) // Description English Integrating Sound Level Meter, in dB(A), from Brüel & Kjær, model 2225. ... Image File history File linksMetadata Download high resolution version (439x1024, 42 KB) // Description English Integrating Sound Level Meter, in dB(A), from Brüel & Kjær, model 2225. ... Integrating sound level meter in dB(A) A sound level meter is used to measure sound levels, usually in terms of subjective loudness. ... Base layer of asphalt concrete in a road under construction. ...

Tire types had considerable design changes in the 1970s, and at this juncture are probably optimized for noise control, given the of safety needs for a significant grip by the tread.

Roadway geometrics and surrounding terrain are interrelated, since the propagation of sound is sensitive to the overall geometry and must consider diffraction (bending of sound waves around obstacles), reflection, ground wave attenuation, spreading loss and refraction. A simple discussion indicates that sound will be diminished when the path of sound is blocked by terrain, or will be enhance if the roadway is elevated so as to broadcast; however, the complexities of variable interaction are so great, that there are many exceptions to this simple argument. The intensity pattern formed on a screen by diffraction from a square aperture Diffraction refers to various phenomena associated with wave propagation, such as the bending, spreading and interference of waves passing by an object or aperture that disrupts the wave. ... Spheres reflecting the floor and each other. ... Ground wave: In radio transmission, a surface wave that propagates close to the surface of the Earth. ... The straw seems to be broken, due to refraction of light as it emerges into the air. ...

Micrometeorology is significant in that sound waves can be refracted by wind gradients or thermoclines, effectively dismissing the effect of some sound barriers or terrain intervention.^[3] The straw seems to be broken, due to refraction of light as it emerges into the air. ... The thermocline is a layer within a body of water where the temperature changes rapidly with depth. ... U.S. Navy F/A-18 at transonic speed. ...

Geometry of area structures is an important input, since the presence of buildings or walls can block sound under certain circumstances, but reflective properties can augment sound energy at other locations.

Computer models for roadway noise

Because of the complexity of the variables discussed, it is necessary to create a computer model that can analyze sound levels in the vicinity of roadways. The first meaningful models arose in the late 1960s and early 1970s addressing the noise line source (e.g. roadway). Two of the leading research teams were BBN in Boston and ESL of Sunnyvale, California. Both of these groups developed complex mathematical models to allow the study of alternate roadway designs, traffic operations and noise mitigation strategies in an arbitrary setting. Later model alterations have come into widespread use among state Departments of Transportation and city planners, but the accuracy of early models has had little change in 40 years. A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ... North-South Expressway in Malaysia; a roadway can be considered as a line source of air and noise pollution and need not be a straight line. ... BBN might refer to: Bolt, Beranek and Newman, (now known as BBN Technologies), a technology company in Cambridge, Massachusetts, best known for its work on packet switching technology Bible Broadcasting Network, a global Christian radio network headquartered in Charlotte, NC Big Bang nucleosynthesis Big Brother Nigeria, a reality show which... Nickname: City on the Hill, Beantown, The Hub (of the Universe)1, Athens of America, The Cradle of Revolution, Puritan City, Americas Walking City Location in Massachusetts, USA Counties Suffolk County Mayor Thomas M. Menino(D) Area    - City 232. ... ESL Incorporated is a high technology U.S. firm engaged in software design, systems analysis and hardware development for the strategic reconnaissance marketplace. ... Location of Sunnyvale within Santa Clara County, California. ... A mathematical model is an abstract model that uses mathematical language to describe the behaviour of a system. ... Roadway noise is the most pervasive form of environmental noise Noise mitigation is a set of strategies to reduce unwanted environmental sound. ... The Department of Transportation (DOT) is the most common name for a government agency in North America devoted to transportation. ...

Generally the models trace sound ray bundles and calculate spreading loss along with ray bundle divergence (or convergence} from refractive phenomena. Diffraction is usually addressed by establishing secondary emitters at any points of topographic or anthropomorphic “sharpness” (such as noise barriers or building surfaces). Meteorology can be addressed in a statistical manner allowing for actual wind rose and wind speed statistics (along with thermocline data). Noise barrier earth berm along Highway 12, Sonoma County, California A noise barrier is an exterior structure, normally made of masonry or earth, designed to protect sensitive land uses from noise pollution. ... A compass rose or wind rose, is a figure displaying the orientation of the cardinal directions, north, south, east and west on a map or nautical chart. ... Wind speed is the speed of movement of air relative to a fixed point on the earth. ...

Case studies

An interesting early case where two of the leading models were pitted against each other involved a proposed widening of the New Jersey Turnpike from six to twelve lanes. The BBN^[4] and ESL^[5] models were on opposing sides of a matter decided in New Jersey Superior Court. This case in the early 1970s was one of the first U.S. examples of acoustical scientists playing a role in the design of a major highway. The models allowed the court to understand the effects of roadway geometry (width in this case), vehicle speeds, proposed noise barriers, residential setback and pavement types. The outcome was a compromise that involved substantial mitigation of noise pollution impacts. BBN Technologies (originally Bolt Beranek and Newman) is a high-technology company that provides research and development services. ... ESL Incorporated is a high technology U.S. firm engaged in software design, systems analysis and hardware development for the strategic reconnaissance marketplace. ... For the Bon Jovi album, see New Jersey (album) Official language(s) None, English de facto Capital Trenton Largest city Newark Area  Ranked 47th  - Total 8,729 sq mi (22,608 km²)  - Width 70 miles (110 km)  - Length 150 miles (240 km)  - % water 14. ... In law, and more specifically, in the Anglo-American common law legal tradition, a superior court is a court of general jurisdiction over all, or major, civil and criminal cases. ... Noise barrier earth berm along Highway 12, Sonoma County, California A noise barrier is an exterior structure, normally made of masonry or earth, designed to protect sensitive land uses from noise pollution. ... A residential area is a type of land use where the predominant use is residential. ... Noise pollution, usually called environmental noise in technical venues, is displeasing human or machine created sound that disrupts the environment. ...

Another early case involved the proposed extension of Interstate 66 through Arlington, Virginia. The plaintiff, Arlington Coalition on Transportation sued the Virginia Department of Transportation on the grounds of air quality, noise and neighborhood disruption. To analyze roadway noise, the ESL model was used by the plaintiff, who won this case partially due to the credibility of the computer model. The matter was revisited a decade later and a greatly reduced highway design with transit element and extensive noise mitigation was agreed to. Interstate 66 (abbreviated I-66) is an interstate highway in the eastern United States. ... Arlington County is a county located in the U.S. state of Virginia (which calls itself a commonwealth), directly across the Potomac River from Washington, DC. By an act of Congress July 9, 1846, the area south of the Potomac was returned to Virginia effective in 1847 As of 2000... A plaintiff, also known as a claimant or complainer, is the party who initiates a lawsuit (also known as an action) before a court. ... The Arlington Coalition on Transportation (ACT) is a citizens group formed to oppose the construction of Interstate 66 through Arlington, Virginia. ... The Virginia Department of Transportation, or VDOT, is the government agency responsible for building, maintaining and operating Virginias roads, bridges and tunnels. ... The Air Quality Index (AQI) is a standardized index of the air quality in a given location, given in parts per billion. ... A computer simulation or a computer model is a computer program which attempts to simulate an abstract model of a particular system. ...

Later cases have occurred in every state, both in contentious actions and in routine highway planning and design. The public as well as governmental agencies have become aware of the value of acoustical science to provide useful insights to the roadway design process.

References

The New Jersey Turnpike (sometimes called The Jersey Turnpike) is a toll road in New Jersey and is one of the most heavily traveled highways in the United States. ... East Brunswick is an suburban township located in Middlesex County, New Jersey. ...

External links

• FHWA's Traffic Noise Model
• Norway noise profile showing roadway noise accounts for 78% of all noise annoyance

See also

• Noise barrier for a deeper insight to roadway noise mitigation using physical barriers
• Noise health effects for a discussion of physiological and psychological impacts
• Noise pollution for a broader discussion of environmental noise
• Noise regulation for the history of noise statutes governing roadway and other noise
• Noise cancellation for a discussion of methods to actively reduce unwanted sound