First version: Because the first railway in the world was built in England, in the final analysis, it was a matter of habit. Many of the early railways in our country were built in Britain. According to the British form, the signal system was set up, the British railway was left, and our railway was of course left. In the early days of the founding of the people's Republic of China, there was limited financial resources, so the habit of leaving the train left behind. After that, the new lines were carried out in order to save energy and labor.
Second version: The first trains invented in England were steam locomotives, and drivers were not as relaxed as they are now. A lot of times, you have to stretch your head from side to side to observe the road condition. At this time, you can only operate by one hand. Which hand is convenient to operate? Most people are used to the right hand, so the driving position is naturally on the left, and the head is extended from the left to observe the road conditions when necessary, and the railway signal facilities are set on the left, and the driving is left. (of course, these are all on the Internet), but the main reason is habit.