一、前言就世界范围来说,铁路路网密度在近半个世纪里无明显变化,在绝大多数国家,铁路货运量在交通运输业中仍占第一位.二次世界大战后的三十年里,随着科学技术的发展,铁路运输技术现代化有明显的进步.从当前情况来看,有如下几个主要特点:1.二次世界大战后独立的发展中国家正在开发资源,考虑本国的工业布局,实施自己的筑路计划和铁路技术改进计划. I. INTRODUCTION As far as the world is concerned, the density of railway networks has not changed significantly in the past half century. In most countries, the volume of railway freight traffic still ranks first in the transportation industry. After the Second World War, In the past ten years, with the development of science and technology, there has been a marked improvement in the modernization of railway transport technology. From the current situation, there are several main features as follows: 1. Independent developing countries after the Second World War are developing resources to consider The country’s industrial layout, implementation of their own road construction plan and railway technology improvement plan.