The separated traffic of green belt has safety function. Green belts can beautify cities and eliminate drivers' visual fatigue. Planting arbor green belts can also change the spatial scale of roads and make the road space have a good width-height ratio. In addition, it also has the function of purifying the environment, which can retain dust, reduce noise, absorb harmful gases and release oxygen.
Greening along the expressway adds organic natural color to inorganic roads and is the main factor of environmental landscape. The landscape design of greening along the expressway should first consider the landscaping function, and at the same time, through effective greening design, strengthen the driver's sight guidance and reduce the tension caused by high-speed driving. The landscape design of greening along the expressway should not only be designed as the isolation belt and shelter belt of the roadway, but also meet the landscape needs along the expressway and the whole expressway. Good greening design can not only reduce the impact of expressway on the environment, but also maintain the ecological balance of flora and fauna, making the whole expressway space full of vitality. Automobile exhaust will bring Pb pollution to the soil and green trees on both sides of the expressway to a certain extent, and the green belts on both sides can protect Pb pollution.