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. Worldwide perspective Even without regulation, there are strong individual economic pressures for quieter vehicles, because owners and employers see quieter vehicles as more luxurious and less stressful. The tighter regulatory requirements of the EU and Japan encourage quieter design even in unregulated countries, because most car manufacturers aspire to international sales. On the other hand, individual owners of motorbikes, 'boom-box' cars (with very loud music systems), and 'muscle-cars' may prefer their vehicle to be louder (at least at idling or low speeds), and such noise (often from modified exhaust systems) can only be controlled by on-going inspection and sanctions. Several studies have concluded that reducing traffic noise pollution is low-cost or cost-effective. Such studies include consideration of the reduced value of noise-affected real-estate, the costs of supporting a dispersed population 'trying to get away from all the noise', and the increased healthcare costs statistically attributable to a noisier environment. European technology began to emulate the United States treatment of roadway noise by the 1980s, although the national requirements of noise studies generally remain less stringent than the U.S. In developing countries, noise pollution from motor vehicles represents a significant impact, but technologies are not as advanced as in Western nations. For example, a recent paper from Iran illustrates a level of technology that the United States encountered in the 1960s. The European Union has recently proposed a set of vehicle tire requirements, similar to those introduced in the U.S. in the 1970s. In Mumbai, India, excessive honking and road noise is seen as a significant nuisance. The local police launched an experimental program in 2020 to link the time-length of red lights to an ambient noise sensor, increasing red light times if ambient noise from traffic exceeds limits. This acts as a deterrent to use of the horn. See also Noise barrier for a deeper insight to roadway noise mitigation using physical barriers Noise cancellation for a discussion of methods to actively reduce unwanted sound General: 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 References External links FHWA Traffic Noise Model Norway noise profile showing roadway