This thesis deals with automated storage/retrieval carousel systems. Expected travel times of the storage/retrieval machines are studied for two types of the systems, one for single carousel and the other for double carousel. For single carousel, it is assumed that the information on the next command is available at the beginning of the execution of the previous one. Based on randomized assignment rule, the expected single and dual command times are determined analytically for most of the cases. For the case with single command in double carousel, the continuous rack simulation is adopted to estimate the travel time.