In most of large and secondary cities, the number of vehicles is increasing rapidly with the stepwise enhancement of social economy and the continuous development of automotive industry. 在大多数大中型城市,随着社会经济水平的逐步提高和汽车工业的迅速发展,机动车的数量急剧增多,越来越多的城市出现道路交通拥挤的现象。