一条铁路在新建时就考虑远期预留较大的通过能力和输送能力,新建时对将来不易 改扩建的工程,以及施工时严重干扰运输的工程,同时施工,虽然在新建时增加了部分工程投 资，但将来改扩建就比较容易，能省下巨额的工程费用，对运输的干扰程度也将小得多。本文 介绍南昆线设计时,对远期扩能方案的研究,考虑到南昆线是沟通西南与华南沿海的重要通 道，西南地区资源丰富,而本线地处桂北山区,云贵高原,工程艰巨，受地形限制增建第二线的 条件十分困难，提出发展重载运输方案，体现了远近结合。

As constructing a new railway，the line capacity and the transport capacity should be preserved sufficiently beforehand for futural developments. The engineering projects, which are difficult to be reconstructed in future and seriously interfere transportation, should be constructed at the same time with the construction of new tracks. Although the partial initial engineering investment may be increased, but the reconstruction projects in future will be proceeded much easy, enabled to save a lot of engineering expenses and less disturbance with transportation. As the geological conditions along the Nanning-Kunming Railway are very complex，the reconstruction of a second railway line will be rather difficult，and thereby a long-term development scheme of heavy-haul transportation has been proposed by the au?thor.