| It is considered that noise is one of " four major environmental public hazards" in the city, having very great danger to people's psychology, physiology. Particularly, traffic noise is a kind of noise that affects urban environment widely and interferes people the most Since 1970s, academic circle and government departments have paid close attention to noise. Lanzhou is the main big city of the Northwest and hub of communications; the urban subject lies in the narrow and long river valley basin. The traffic noise is seriously polluted. It covers an area of 1.31 X 104km2, with an urban area of 163 km2 and a population of 3.14 X104. There are five national roads crossing Lanzhou City, which are Road 312, Road 310, Road 109, Road 212, Road 213, and six provincial roads. The total length of the roads is 1600 km. The range the thesis covers is four administrative districts ( Anning District, Chengguan District, Qilihe District and Xigu District), including 52 roads( 29 major roads with a total length of 76.74km and 23 secondary roads of 48.61 km), a total length of 125.35 km and a total area of 2449km2. The monitored places are 142.The increase amount of the volume of traffic is large in the past 14 years in the main road of Lanzhou, and the annual change law is obvious. The volume of traffic obeys the expression formula of the relation with the change of time (1). The volumes of traffic annual change and quantity of bus, taxi of Lanzhou have very remarkable relevant relations, and its line shape function is an expression formula (2). The road of Lanzhou going the composition of the vehicle relies mainly on compact car in 2002, and its proportion accounts for 72.3%. Law of space distribution of the volume of traffic of the road in Lanzhou is that Anning District>Chengguan District >Qilihe District >Xigu District according to administrative area, and west east roads>north-south roads according to direction of roads.Q = 447.737-22.351h + 23.412h2-1.155h3(R2 = 0.95;Sig = 0.000).........(1)In the type, Q is the volume of traffic, h is yearY = 151.757 + 151.757N1 + 0.0695N2(R = 0.981)..........................(2)In the type, Y is the average annual volume of traffic of the road (vehicle/one per hour); Nl is the quantity of bus( one); N2 taxi's quantity ( one)Traffic noise makes serious pollution in Lanzhou City during last 14years, and the undulating characteristic of noise is obvious, Strong enough to the public interference. The annual change law of the traffic noise is remarkable; roughly divide three stages, for the period of rising of noise pollution of traffic in 1989-1993 years, Dropped period by a wide margin for the noise pollution of traffic in 1993-1998, the noise annual change of the traffic tended towards gentle in 1998-2002. Traffic noise makes a distinction between major roads and secondary roads. Main roads and secondary roads traffic noise have obvious difference, main roads traffic noise exceed standard seriously. But secondary roads traffic noise undulating characteristic is obvious, having better interference to the public. According to the evaluation parameter Leq, the pollution can be ranked as : Chengguan District> Qilihe District > Anning Dstrict > Xigu District, Anning District > Qilihe District > Chengguan District > Xigu District according to the evaluation parameter L10. and Xigu District>Chengguan District> Anning District>Qilihe District according to the evaluation parameter Lnp.Through investigating and analyzing, the traffic noise current situation of Lanzhou: polluted seriously; the exceeding standard rate is high; the law of space distribution of noise of the traffic is remarkable. Chengguan District is the most serious pollution area and Anning District is the area with thelest pollution. The traffic noise on the major roads is more serious than that on the secondary roads, but the traffic noise on the secondary roads has obvious undulating, the pollution of the traffic noise on the west-east roads and double function roads is worse than that on the north-sout... |
