Effects Of Urban Light Rail Transportation Noise On Environment And Case Study

The transportation is a nation's economic life vein. With rapiddevelopment of modern economy, especially swift increase of mobilecars, traffic problem becomes more and more serious. Narrow roads,traffic jam, frequent traffic accidents and increasing air pollution,make people's living environment worse and worse. For the sake ofthe environmental protection and resolving people's problem"difficultly of going outside", people have generally realized that onlythe public transportation development is the best exit. With economy's super-speed development and population'scontinuous increase, our city public transportation development hasentered a brand-new stage. Because rail transportation has manyadvantages, such as large carrying capacity, quick speed, cozycircumstances, safety, stability and small land occupation, it comesfirst in the city transportation construction. The rail transportation includes subway, light rail, trolley car andcity railroad, all using electric power as driving force. Compared withtraditional bus, circulation of rail transportation can reduce dischargingof air contamination such as N2O and CO etc. and reduce air pollution.In rail transportation, subway and light rail get more of people's favor.Nevertheless, the period of subway construction is long andinvestment is large. Aiming at our nation's concrete situation, choosinglight rail transportation of medium passenger transport capacity, lowerprice than subway (1/3 price of subway) and short construction periodis more applicable. Furthermore, light rail transportation is moreflexible as it can run on the ground rail and also on elevated rail, evenin the underground rail. Light rail transportation is similar with railroad transportation,following train transportation form of certain orbit, socontaminative problem caused by light rail transportation can not beignored, especially noise pollution problem. The rail transportationshould follow the road of sustainable development. At the same timeof solving transportation problem, we should also maintain good livingenvironment. A. The characteristics of light rail transportation noise The noise of light rail transportation system is mainly the gratingbetween car wheel and steel rail, bump sound, screech of triggeringand vibration radiation sound; noise of the motive system includesoperating sound of motive machine, compressor, wheel gear box etc;in addition to wheel and rail noise, bodywork radiation noise anddraught electric machine noise, elevated light rail noise also includesbridge formation noise. Furthermore, compared with ground light rail,its noise has larger radiation cover and wider influence scope. B. Prevention of light rail transportation noise pollution Because light rail transportation is a close system and the orbit ofrail train is fixed, compared with " scattering noise" created by mobilecars, noise of light rail transportation is relatively concentrated andeasier to manage. Light rail noise prevention should begin with lowering noisesource, making railroad train motive system noise as low as possible. First, adopt measures from train's structure and design, andproceed vibration prevention and sound absorption. Use damp wheeland dish type brake, repair train stepping surface, and add noiseprevention skirt to the two sides of the train. Second, adopt vibrationdecreasing and noise lowering measures on rail and bridge structure,for example, use extra long seamless steel rail instead of standard steelrail to reduce vibration and noise caused by wheel's bump to steel rail,which can lower noise 3～5dB(A); install flexible polymer mortarlayer and whole roadbed with flexible fastener to absorb vibrationwave, which can lower noise 10dB; polish steel rail periodically andkeep smooth of rail to lower vibration noise created by wheel and steelrail's friction, impact and unequal abrasion, whi...