国家公路设计规程反映的是主要公路要求,不反映一般郊区公路,因为郊区公路仅仅每天通行几百辆车。但在全国有三分之二的公路属于低交通量的郊区公路。这些公路不仅仅是一些数量大的单一等级的公路,而且它也将一些分散的村落联系起来,并使农场和森林产品到达消费者手中,也便于郊区 National highway design codes reflect major road requirements and do not reflect typical suburban highways, as suburban highways pass only a few hundred cars per day. However, two thirds of the country’s roads are suburban highways with low traffic. Not only are these highways a number of single-class highways, but they also link scattered villages and bring farms and forest products to consumers and suburbs