交通运输是国民经济的动脉,它对社会经济发展和人民生活起着极为重要的作用.各种运输方式在日常运输营运管理工作中都要面对这样一个共同的问题:如何为其载运工具(汽车、列车、轮船和飞机,以下统称为车辆)确定行驶路线及其时刻表,才能有效地运送各站点间的旅客和货物.(Transportation is the artery of national economy, the social economic development and people's life plays a very important role. The various modes of transport have to face such a common problem in the daily transportation operation management: how to work for the vehicles (cars, trains, ships and airplanes, hereinafter referred to as the vehicle to determine) routes and schedules, in order to effectively deliver the site between passengers and cargo.)