If you go to a company, you don't actually major. What this company needs is a generalist. You are a project management major, but you may not be able to manage the project well. This major is a bit of management, but such a company needs more skilled employees. Your specific position depends on what kind of talents are lacking in the branches of 17 bureau, so you are generally engaged in this field. In order to consider the labor cost, China Railway usually requires you to master all kinds of knowledge and know the skills of various positions.
It is very likely that you will go to the company to do engineering procurement, which is convenient. But not necessarily. I'll arrange it for you anyway. The first year is a probation period, which will largely integrate your performance this year, and arrange you to go to specific positions in combination with your strengths and the positions that the company lacks.
Life in China Railway is rather boring. Only by enduring loneliness can you become a mainstay in the big waves. I wish you success in China Railway.