In this paper we propose an ACO approach, where two colonies of ants aim to optimize total costs in a transportation network. This main objective consists of two sub goals, namely fleet size minimization and minimization of the vehicle movement costs, which are conflicting for some regions of the solution space. Thus, our two ant colonies optimize one of these subgoals each and communicate information concerning solution quality. Our results show the potential of the proposed method. / Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"