I. Introduction
Over the last decades, there has been great attentions dedicated to the research of autonomous vehicles. The rapid development of artificial intelligence (AI) and communication technologies has made it possible for autonomous vehicles to enter into a wide range of transportation applications [1]–[3]. The decision making system, which is responsible for enhancing operational safety, improving traffic capacity and alleviating driver fatigue, is one of the most crucial technologies for autonomous vehicles. For the high-speed railways, the high level of safety, punctuality, riding comfort and complex environment puts a strict requirement on the development of the decision making system for the autonomous driving of high-speed trains.