By Li Qian

Beijing published its first map of traffic noise that enables viewers to see how the different urban districts are affected by noise pollution from the city's boulevards and streets.

The sample map, covering an area of 12.7 square kilometers in Haidian district, shows, in different colors, noise in decibels for each residential or commercial building – the farther it stands from the traffic, the quieter it is.

The Beijing Municipal Institute of Labor Protection under the Beijing Academy of Science and Technology worked out the map through simulations modeled on computer.

Researchers collected samples from the sounds made by motor vehicles and calculated the decibels emitted from the road by multiplying the traffic volume on different kinds of roads, said Hu Wencheng, engineer at the institute.

As Beijing expands quickly and more roads are constructed, the city has become more boisterous from surging traffic volume, which is a major source of noise pollution in large cities.

However, it is a challenging task to silence Beijing, as the city has a great deal of ring roads and highways that go through downtown areas. "These roads, which are fairly wide, make it largely ineffective to install sound-proof barriers on main roads, especially for high-rises," Hu said.

Traffic noise has become a common source of complaint. There is frequent news about residents living in apartment buildings alongside highways suing the property developer for selling homes that are open to excessive noise.

National law requirements state that noise should be no higher than 55 dB during the daytime and lower than 45 dB at night in residential areas.

"The map could serve as a reference for urban planning," Hu said, "so that the government can reduce the density of people in some noisy residential areas." Also, residents are empowered to choose a tranquil place to live by consulting the noise map.

After the samples have been collected, the institute will continue to draw up a "noise map" of the entire city, which takes into consideration not only road traffic but also planes, railways and non-traffic noise.

But Hu said the program is yet to be approved and funded by the environmental protection bureau.