I. Introduction
More and more people choose the railway as their first choice because of the efficiency, convenience, and low price, which causes a dramatic increase in energy consumption. Train eco-driving optimization has attracted people's attention for a long time. The purpose is to complete the transportation tasks from the departure station to the arrival station with the least energy consumption without violating safety regulations. The regular eco-driving problem treats the journey between stations as a whole. The optimal speed trajectory can be generated by Driver Advice System and implemented by the driver or calculated and executed by the Automatic Train Operation system.