Sleepers [1] were originally made of wood, which has good elasticity and insulation, is less affected by temperature changes in the surrounding medium, is lightweight, easy to process and replace on the line, and has sufficient displacement resistance. After anti-corrosion treatment of wooden sleepers, the service life is also greatly extended, about 15 years. Therefore, 90% of the world's railways use wooden sleepers.
According to statistics, at the peak of the use of wooden pillows, more than 3 billion sticks were laid around the world, and most of them were pine. As you can imagine, how much forest would have to be destroyed?
With the decline of forest resources and the enhancement of people's awareness of environmental protection, of course, because of the development of science and technology, at the beginning of the last century, some countries began to produce steel sleepers and reinforced concrete sleepers to replace sleepers. However, because the metal consumption of steel pillows is too large, the cost is expensive, and the volume is also bulky, it has not been promoted, and only a few countries such as Germany are still using it. And many countries have begun to produce reinforced concrete sleepers generally since the 50s of the last century.