As we all know, the main rail of the train track is composed of the top rail and sleepers, and there is a road paved with gravel as the foundation under this main rail. Just knowing the structure is not enough to get the answer we want. Let's analyze step by step, why do we need sleepers? Because our train tracks are made of steel, and high-speed trains will rub against the tracks. Generate huge heat, which will lead to the deformation of steel.
If there is no external force to fix our steel, it will slowly extend in other directions, and we rely on the extension direction of the rail to control the direction of the train. Sleeper is an important tool to fix the rail on the fixed track without deformation. In addition, the passenger capacity and self-weight of our train are very huge.
If we only rely on the contact area of the rail, the ground under the rail will bear great pressure, which will cause the ground to break and the rail will sink in. So in order to reduce the pressure on the ground, sleepers are added to increase the contact area. The foundation paved with gravel is to prevent the whole main line from sinking and increase the buffering effect. There is also the use of fragile stones to absorb the heat generated by the friction between rails and trains.
Railway rails are widely used in crown block tracks, which is different from our trains. They are very light, and the number of passengers is far from the level of trains. Plus they are running in the city, so the speed is not too fast. There will be no trains on the track. In order to use the roads with cars in the city, it is naturally impossible to build the track into a train. Therefore, most of them use tracks that are slightly buried in the road, which is the biggest difference between train tracks and tram tracks. Although the appearance of subgrade is different, other structures are basically the same. And the track of the tram is 60 kilograms per meter.