铁路是国民经济的基础产业和主要交通运输工具。列车重量、密度、速度是提高铁路运输能力、质量和效益的三大要素,合理确定其发展水平,优化三者的组配是近期我国铁路发展政策的核心。科学技术在铁路提高能力、保证安全、增加效益等方面起到了重大作用。但是,我国铁路运输能力不 Railway is the basic industry of the national economy and the main means of transport. The weight, density and speed of trains are the three major factors that enhance the capacity, quality and efficiency of railway transportation. The reasonable determination of their level of development and the optimization of the three are the core of China’s railway development policies in the near future. Science and technology have played a significant role in enhancing the railway capacity, ensuring safety and increasing efficiency. However, China’s rail transport capacity is not