The Analysis Of Traffic Noise Characteristic And The Effect Of Afforested Belt Noise Reduction

With the rapid development of our country economic and the rapid inflation of the population, the highway construction has been the fast development orbit continually. It makes the great contribution for the national economy and the social development. While the highway traffic noise, which is one of main environmental damages, is restricting gradually the raise of residents' life quality. It has been the utmost of important matter to prevent and control the road noise pollution for the road department, the transportation department and the environmental protection department.This article has detailed analysis of the highway traffic noise production reason, its characteristics, the harm to the person, and current main government measure. By comparisons of several kind of commonly used advantage and disadvantage noise reducing measures, from protected the whole world eco-environment and the long-term sustainable development angle, some points had been to decrease traffic noise by adopting greenbelt. Based on the domestic and foreign afforested belt noise reduction research foundation, a series of new viewpoints have been proposed which has certain reference value for the urban afforestation and highway environmental construction.This experiment had been from two aspects on research afforestation belt noise reduction effect: on the one hand had mainly studied the noise reduction rule of the afforested lawn, by comparisons of reducing the traffic noise in the two big kind of commonly used afforestation lawns of Guanzhong Area (high sheep bushes and so on four kind of gramineae lawns and leguminosae's trifolium repens). The results indicate that: the sole grass plants the lawn has good effect on reducing the traffic noise, continuously equivalent acoustic level (Leq) along with the traversing lawn distance increase, the noise reduction gradient along with the increase, when is apart from acoustic source 4~8m, the gradient starts to increase, when 8~12m, the gradient maximizing, along with the distance further increase, the noise reduction gradient starts to reduce, but the noise reduction total quantity is also increasing, when the lawn width achieved when 12m, the noise reduction effect is remarkable. Namely the main achievement noise reduction use lawn, the display noise reduction function effective width most is small is 12m. Gramineae high sheep fescue lawn noise reduction effect obvious good in leguminosae's trifolium repens level ground is suitable for in the city high chirp road section planter. When identical measuring point different highly, the lawn near ground high frequency traffic noise weakens the effect to be obvious.On the other hand mainly studies the afforested forest belt the noise reduction rule, insults two places and the peripheral locality 13 afforestation forest belts to Shuangyashan and Yangling carries on monitors on the spot, through the massive measured data, to afforested the forest belt the noise reduction effect to carry on the analysis, the proof, obtained the forest belt noise reduction lowest establishment effective width to be supposed to be 16m, the use afforestation forest belt noise reduction, its effect was decided by the tree seed, the visibility, the planter width, the crown, factors and so on forest belt structure as well as seasonal variation, in which visibility and the width is highly the most important two factors.The noise attenuation and the penetrability are in reverse proportion, is proportional with the width; When different structure forest belt noise reduction effect contrast, after arbor fills the interlacing mix planter > front to fill arbor to mix the planter > the scrub forest > the tree forest; The crown belongs to the main body noise reduction spot, through the spectral analysis discovery, the forest belt surpasses low frequency to the high frequency noise reduction effect, has the better weaken effect to the high frequency noise; Has when the afforested belt plants, in on the vertical highly traffic noise weakens obviously good in non-afforests the belt the situation. Between the noise source and the building, must reasonably dispose the afforested belt which (or abscission period short) the tree and the bush is composed by Chang Lv, also the nearness noise source tree-planting is friends with compared to the nearness protection object tree-planting effect. The forest belt should better be broad-leaf, the dense tree seed, the winding point is low, the branches and leaves cover, the vertical distribution, achieves arbor and bush matching and the close planting; According to the experimental result, proposed plants trees first, a kind of grass afforests, latter builds roads the construction viewpoint.