I just wonder about when it becomes actually used. If an elevator can move in either vertical and horizontal, it means that their paths of movements will be a grid instead of parallel vertical lines. If different people want to get the same elevator from different origin points to different destination points, how the computer system manage the most effective ways of carrying these people? If there are more than one cabs on this grid, it might be more likely that two cabs might get into the same part of grid and collide. How will they design their controlling system to prevent said collision? These just pop in my mind.