Why is the common railroad roadbed is wood and sleepers, while the high-speed rail is all concrete?

Traditional railroad track usually consists of two parallel rails, the rails are fixed on the sleeper, under the ballast made of small gravel. Both ballast and sleeper play the role of increasing the force surface, dispersing the train pressure, and helping the rail to bear the weight, so as to prevent the rail from sinking due to too much pressure. In addition, ballast (small gravel) has several other effects: reducing noise, absorbing heat, damping vibration, increasing water permeability, and so on. This is ballasted track. Traditional ballasted track is characterized by easy laying and low comprehensive cost, but it is easy to be deformed, frequent maintenance, and large maintenance cost. At the same time, the train speed is limited.

The concrete you are talking about is actually ballasted track, consisting of rails, fasteners and unit plates, which play a role in shock absorption and pressure reduction. Ballastless track rails itself is poured concrete, and the roadbed does not use gravel, rails, rails directly on the concrete road. Ballastless track is the world's advanced track technology, can reduce maintenance, reduce dust, beautify the environment, and train speed can reach more than 300 kilometers per hour.