Combustion requires three elements: fuel, oxygen and temperature. When methanol leaks and comes into contact with oxygen, the circuit on the car will be damaged and an electric spark will be generated to ignite methanol after rear-end collision. In addition to the above three elements, the explosion also needs to reach the explosion limit. Methanol itself is a liquid, which can naturally flow around after leaking from the tank, and the fire naturally spreads rapidly. In addition, the liquid that shakes up and down in the tank car because of the uneven road surface will also generate and accumulate static electricity, which is why all tank cars will drag an iron chain behind them.