Study And Practice On The Planting Disposition Of Expressway Greening

The planting disposition in median divider belt and side slopes belt of Chinese expressways were analyzed with typical cases, moreover studies two main problems of the planting disposition were studied: (l)According to the standards on The Design and Construction Technical Specification for Expressway Safety Facility, at the vertical-curved section of The Chengdu-Nanchon Expressway and The Chengdu-Ya'an Epressway, the dizziness-preventing height of planting in middle departing belt, not to be considered by the effects made by the angle of the beam of head lamps, can be calculated. We will compare and regress the different inspected results to give a regression equation between the radius of cylinder and the height of the dizziness-preventing plants. (2)Choose the vegetation coverage, roots, survival rate of plants, soil density, soil antier-odibility, the contents of soil organic matter, the height and the width of Cinnamomum septentrionale Hand Mazz and Cryptomeria fortunei as the principals of greening effects on different planting disposition .(1)Study the differences greening effects on "plant grasses alone" disposition, Cinnamomum septentrionale Hand Mazz -grass disposition and Cryptomeria fortunei -grass disposition in the section of Chengdu-Ya'an expressway , the results are:(1) The effects of Cinnamomum septentrionale Hand Mazz -grass disposition and Cryptomeria fortunei -grass disposition are better than " plant grasses alone" disposition at the study section of Chengdu-Ya'an expressway.(2) Cinnamomum septentrionale Hand Mazz -grass disposition is more suitable for greening than Cryptomeria fortunei -grass disposition at the section of Chengdu-YaAn expressway(2)The height of dizziness-preventing planting in median divider belt, under mountain area expressway is:(1)Not to consider the headlamp' angle of beam, the dizziness- preventing height according to the formula is smaller than it really to be. The height in face is higher than the demanded height when cars are regarded as two points.(2)In mainline segment, the dizziness-preventing height will not change fundamentally, but in concave-verse segment ,we need to heighten the dizziness-preventing height. And a regressing equation Y=l 92.4-0.005X was established on the basis of data from the studying between the vertical-curved radius of cylinder and the dizziness-preventing height, which indicates that on the effect of all factors of expressway, the highest dizziness-preventing height of the central reserve is 1.92m and the lowest is 1.09m.The height will decrease with increase of radius of the cylinders.Integrating theory with practice, the paper gives a planting disposition practice of The Nanchong -around-city Expressway...