When the trains on the Qinghai-Tibet Railway pass through Golmud, it is necessary to replace the locomotives with those imported from the United States. Obviously, our trains have led the world. Why should we do this? As we all know, the Qinghai-Tibet Plateau is very high above sea level, which is very different from other areas. Many people will have some altitude sickness when they come here. This is not only for ordinary people, but also for trains passing here. The whole line of Qinghai-Tibet Railway is divided into two sections, which are separated by Golmud on the way. The topography and environment of the two places are completely different. The topography of the former section is relatively flat, and this section of the line is from Xining to Golmud. The total length of this section is 814 kilometers, which is the key to get through the passage into Tibet. The railway with only 800 kilometers took 26 years to build, and it was not completed until 1984. The overall terrain of this section is still relatively flat, and the altitude increase is not very large, so the train in this section adopts a relatively wide range of electric drive, but the speed can not exceed 160 kilometers per hour. The second section of the Qinghai-Tibet Railway is from Golmud to Lhasa. Compared with the first half, the second half is built on the Qinghai-Tibet Plateau with very high altitude and very different topography. The higher the altitude, the thinner the air, the special geographical environment and the completely different environment from the original one, thus increasing the difficulty of construction. It is actually very difficult to build a railway in Tibet, Qinghai Province, not only to overcome the altitude, but also to face a series of problems such as frozen soil.The upper layer is seasonal frozen soil, which will melt with the increase of temperature, and it will be frozen again in winter. The lower layer is permafrost, which will not melt all year round. The construction process of Qinghai-Tibet Railway is extremely difficult and tortuous. It is worth noting that in the first phase of the railway construction, the locomotive adopted by the train is a domestic locomotive. Once it passes through Golmud, the locomotive will be replaced once, so the original locomotive will no longer be used, but a special locomotive made in the United States will be replaced. The name of this locomotive is called the locomotive head of internal combustion engine. Diesel locomotives face the problems of plateau, which is stronger than the electrified railway at present. In order to successfully complete railway transportation, the slope of plateau becomes larger and the train has been climbing. Trains need to overcome plateau frozen soil and ecological sensitivity. In this case, only the coal-fired power system produced in the United States can maintain the traction of the train. In our country, trains are usually powered by electricity, and this kind of power system is more suitable for trains traveling between cities, that is, those relatively flat and low-altitude road conditions. In such a bad situation, if we continue to use the locomotive in China, then we need to build cables on both sides of the road, so we need to invest a lot of manpower, material resources and financial resources. Originally, the cost of building the Qinghai-Tibet Railway was many times higher than that of other railways. If we build another set of cables needed for electric drive, and this cable is only provided for locomotives. Under such harsh conditions, the requirements for locomotives are also strict.Domestic locomotives, in addition to the driver’s super-high driving skills, should also arrange the corresponding substation, so as to ensure that the train runs forward with sufficient electricity.