进入21世纪,由于国内外汽车生产行业的迅猛发展,汽车生产量及保有量增加幅度急剧上升,大吨货运车辆及家庭轿车进入生活当中,人们才意识到一个突出的问题,就是车辆的增长与道路发展极不协调,交通拥挤,道路破坏严重。目前,全世界拥有汽车几亿辆,我国汽车拥有量仅北京市就有200多? In the 21st century, due to the rapid development of automobile manufacturing industry both at home and abroad, the increase of automobile production and possession has risen sharply. When large tonnage of goods vehicles and family cars enter into life, people realize that the prominent problem is the growth of vehicles Road development is extremely uncoordinated, traffic congestion, serious road damage. At present, there are hundreds of millions of cars in the world, and there are more than 200 cars in Beijing alone in our country.