A power outage occurs when there is an interruption to traction power system. In such emergency situations, trains are expected to achieve autonomy operation powered by onâboard energy storage systems (OESS). This paper presents optimization models and methods to find optimal driving strategies for train emergency operation. Specifically, a nonlinear and nonâconvex program is first formulated in spaceâdomain to minimize trip time under the limits of power and energy capacity of OESS. To improve computational efficiency, the time dynamics is removed from constraints and adjoined to the cost function. Furthermore, convex modelling steps are proposed to reformulate the problem as a convex program that can be solved efficiently. A biâlevel algorithm is designed to obtain optimal driving strategies that can arrive at destinations as soon as possible. Compared to energyâoptimal driving strategies, the proposed methods can effectively reduce the trip time.