随着公路运输在国民经济中地位和作用的提高,公路运输的发展趋势将是大车流量、大载重量、高速行驶,而且随着对外开放政策的实施、社会交往的增加、观念的转变,公路的功能已不只是满足通行的需求,人们还要求它提供快速、安全、舒适、优美的交通环境。为此,公路建设者们除根据国家财力适量地修建一些高等级公路外,一个极其重要的任务就是 With the improvement of the status and function of road transport in the national economy, the development trend of road transport will be traffic flow, heavy load and high speed. Along with the implementation of the policy of opening to the outside world, the increase of social interaction and the change of concept, The function of the highway has not only satisfied the need of traffic, but also demands that it provide a fast, safe, comfortable and beautiful traffic environment. To this end, road builders in addition to the appropriate amount of state financial resources to build some high-grade highway, one of the most important task is