Lu Ping'an and Miss Lina returned on a special train... To be precise, it was a temporary passenger carriage tacked onto a freight train.
Lu Ping'an has never liked the trains of this era; he's quite displeased with these so-called "express trains" that only travel at speeds between 30 to 80 kilometers per hour... But unless something unexpected happens, these trains are destined to be the mainstay of the era.
The other side of the two different world lines is the inevitable divergence in certain technologies, a subtle difference due to physical laws, but the main reason is the fundamentally different "needs".
In a peaceful world that pursues development, high-speed trains are unquestionably an important infrastructure that drives economic growth.