世界性的难题及其出路行路难是全世界大城市的通病。究其原因主要是人口膨胀,交通量猛增。19世纪初全世界人口只有10亿,1930年增加到20亿,1975年翻番达到40亿,今年已达50亿。增加的人口都往城里跑,过去40年世界人口增加1倍,而城市人口却增加2倍。1950年全世界只有7个超过500万人口的 The world’s problems and their difficulties are the common problems in big cities around the world. The main reason is that the population is expanding and traffic is soaring. At the beginning of the 19th century, the population of the world was only 1 billion. In 1930, it increased to 2 billion, and in 1975 it doubled to 4 billion, and this year it has reached 5 billion. The increased population has run into the city. The world population has doubled in the past 40 years, while the population of the city has doubled. In 1950, there were only 7 people in the world with a population of more than 5 million.