Amidst increasing demands for port automation, there is growing attention towards automation strategies through retrofitting of aging rubber-tired gantry cranes (RTGC) in aging ports. RTGC, capable of moving between adjacent blocks rather than being fixed to specific container block, requires a generalized model and methodology regarding the number of blocks and cranes for optimal operational planning. This study presents a 2-block 3-crane scheduling methodology considering the flexible mobility of RTGC. By applying a rolling-horizon approach based on a mixed integer programming model for establishing optimal operational schedule, the study enables the rational resolution of problems within a reasonable time. Experimental results using CPLEX demonstrate that employing the rolling-horizon approach proposed in this study maintains or improves the objective function value compared to conventional mixed integer programming methods while significantly reducing problem-solving time.