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Roadway Noise
Roadway noise is the collective sound energy emanating from motor vehicles. It consists chiefly of road surface, tire, engine/transmission, aerodynamic, and Brake, braking elements. Noise of rolling tires driving on pavement is found to be the biggest contributor of highway noise and increases with higher vehicle speeds. In developed country, developed and developing country, developing countries, roadway noise contributes a proportionately large share of the total societal noise pollution. In the U.S., it contributes more to environmental noise exposure than any other noise source. History Roadway noise began to be measured in a widespread manner in the 1960s, as computer modeling of this phenomenon began to become meaningful. After passage of the National Environmental Policy Act and Noise Control Act, 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 no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise Regulation
Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972,U.S. Noise Pollution and Abatement Act of 1972, P.L. 92-574, 86 Stat. 1234, - other local and state governments passed further regulations. A noise regulation restricts the amount of noise, the duration of noise and the source of noise. It usually places restrictions for certain times of the day. Although the United Kingdom and Japan enacted national laws in 1960 and 1967 respectively, these laws were not at all comprehensive or fully enforceable as to address generally rising ambient noise, enforceable numerical source limits on aircraft and motor vehicles or comprehensive directives to local government. Accordingly, Greece established in 1996 according to Police Order 3 the hours of common quiet 15:00 to 17:30 and from 23:00 to 07:00 in the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflection (physics)
Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The ''law of reflection'' says that for specular reflection (for example at a mirror) the angle at which the wave is incident on the surface equals the angle at which it is reflected. In acoustics, reflection causes echoes and is used in sonar. In geology, it is important in the study of seismic waves. Reflection is observed with surface waves in bodies of water. Reflection is observed with many types of electromagnetic wave, besides visible light. Reflection of VHF and higher frequencies is important for radio transmission and for radar. Even hard X-rays and gamma rays can be reflected at shallow angles with special "grazing" mirrors. Reflection of light Reflection of light is either '' specular'' (mirror-like) or '' diffuse'' (retai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffraction
Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture. The diffracting object or aperture effectively becomes a secondary source of the Wave propagation, propagating wave. Diffraction is the same physical effect as Wave interference, interference, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. Italian scientist Francesco Maria Grimaldi coined the word ''diffraction'' and was the first to record accurate observations of the phenomenon in 1660 in science, 1660. In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. The characteristic pattern is most pronounced when a wave from a Coherence (physics), coherent source (such as a laser) encounters a slit/aperture tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tire Label
The Tyre Label is a mark for motor vehicle tyres. Manufacturers of tyres for cars, light and heavy trucks must specify fuel consumption, wet grip and noise classification of every tyre sold in EU market starting in November 2012. For passenger car, light truck and truck tyres the information must be available in technical promotional literature (leaflets, brochures, etc.), including the manufacturer website. For passenger and light truck tyres, the manufacturers or importers have the choice of either putting a sticker on the tyre tread or a label accompanying each delivery of batch of tyres to the dealer and to the end consumer. The tyre label will use a classification from the best (green category "A") to the worst performance (red category "G"). This initiative results from a regulation by the EU Commission released in 2009. It is part of the Energy Efficiency Action Plan, designed to improve the energy performance of products, buildings and services to reduce energy consump ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubberized Asphalt
Rubberized asphalt concrete (RAC), also known as asphalt rubber or just rubberized asphalt, is noise reducing pavement material that consists of regular asphalt concrete mixed with crumb rubber made from recycled tires. Asphalt rubber is the largest single market for ground rubber in the United States, consuming an estimated , or approximately 12 million tires annually. Use of rubberized asphalt as a pavement material was pioneered by the city of Phoenix, Arizona in the 1960s because of its high durability. Since then it has garnered interest for its ability to reduce road noise. In 2003 the Arizona Department of Transportation began a three-year, $34-million Quiet Pavement Pilot Program, in cooperation with the Federal Highway Administration to determine if sound walls can be replaced by rubberized asphalt to reduce noise alongside highways. After about one year it was determined that asphalt rubber overlays resulted in up to 12 decibels of in road noise reduction, with a typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bitumen
Bitumen ( , ) is an immensely viscosity, viscous constituent of petroleum. Depending on its exact composition, it can be a sticky, black liquid or an apparently solid mass that behaves as a liquid over very large time scales. In American English, the material is commonly referred to as asphalt or tar. Whether found in natural deposits or refined from petroleum, the substance is classed as a pitch (resin), pitch. Prior to the 20th century, the term asphaltum was in general use. The word derives from the Ancient Greek word (), which referred to natural bitumen or pitch. The largest natural deposit of bitumen in the world is the Pitch Lake of southwest Trinidad, which is estimated to contain 10 million tons. About 70% of annual bitumen production is destined for road surface, road construction, its primary use. In this application, bitumen is used to bind construction aggregate, aggregate particles like gravel and forms a substance referred to as asphalt concrete, which is collo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concrete
Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactured material in the world. When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that can be poured and molded into shape. The cement reacts with the water through a process called hydration, which hardens it after several hours to form a solid matrix that binds the materials together into a durable stone-like material with various uses. This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed. The hydration process is exothermic, which means that ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans or superplasticizers) are included in the mixture to improve the physical prop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Groove Wander
Groove wander, similar to tramlining, is a lateral force acting on a vehicle's wheel resulting from the combination of rain grooves (grooves cut into roads to mitigate hydroplaning in light rain conditions) and contoured deformations in the road surface upon which the wheel runs. When the contact patch of the tire does not form to match the contours of the road surface the stiff tire edges tend to ride on and be guided (or tramlined) by the rain grooves within the surface contour. This force is greater than the contact patch can counter and the resultant force is delivered to the wheel hub and axle, pushing the car laterally. When all four wheels are acted upon in this way, the vehicle can experience rapid forces occurring from side to side and corner to corner (similar to encountering wind gusts, only from all four directions instead of just one). A mismatch between tire design and vehicle weight, or vehicle suspension design, or simply wheel alignment can all contribute to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chip Seal
Chipseal (also chip seal or chip and seal or spray seal) is a pavement surface treatment that combines one or more layers of asphalt with one or more layers of fine aggregate. In the United States, chipseals are typically used on rural roads carrying lower traffic volumes, and the process is often referred to as asphaltic surface treatment. This type of surface has a variety of other names including tar-seal or tarseal, tar and chip, sprayed seal surface dressing, or simply seal. In Australia as well as New Zealand, chipseal roads are common, including usage on major highways. Uses Chipsealing is cheaper than resurfacing an asphalt concrete or a Portland cement concrete pavement, but not as long-lasting. Installation Chipseals are constructed by evenly distributing a thin base of hot tar, bitumen or asphalt onto an existing pavement and then embedding finely graded aggregate into it. The aggregate is evenly distributed over the hot seal spray, then rolled into the bitumen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-weighting
A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighting is applied to instrument-measured sound levels in an effort to account for the relative loudness perceived by the human ear, as the ear is less sensitive to low audio frequencies. It is employed by arithmetically adding a table of values, listed by octave or third-octave bands, to the measured sound pressure levels in dB. The resulting octave band measurements are usually added (logarithmic method) to provide a single A-weighted value describing the sound; the units are written as dB(A). Other weighting sets of values – B, C, D and now Z – are discussed below. The curves were originally defined for use at different average sound levels, but A-weighting, though originally intended only for the measurement of low-level sounds (aro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
