At first, the sleeper is made of wood, the elasticity and insulation of the wood are good, the temperature change of the surrounding medium is small, the weight is light, the process and the on-line replacement are simple, and there is enough displacement resistance. After the anti-corrosion treatment of the sleepers, the service life is greatly extended, in 15 years or so. So, 90% of the world's railways use sleepers.
According to statistics, at the peak of sleepers use, around the world about more than 3 billion of the laying and mostly pine. Can you imagine how many forests this has to destroy?
With the decrease of forest resources and the enhancement of people's awareness of environmental protection, of course, because of the development of science and technology, some countries began to produce steel pillow and reinforced concrete sleeper to replace sleepers. However, because the steel pillow metal consumption is too large, expensive, bulky, not spread out, only a few countries such as Germany is still in use. Many countries have begun to produce reinforced concrete sleepers since the 50 's.