In order to identify the possible factors influencing the collec- tion and transportation costs of recyclable glass-waste, an analysis considering the established goal and the defined boundaries of the system under study, and the discussions with Amarsul, yielded the cost function expressed by Eq. (6). The cost function comprises the labor cost and vehicle operation cost, including maintenance. One should stress that the capital cost is of importance but it was not taken into consideration since the goal established for the studied case was to optimize an already existing system (with the invest- ments already done in the past) rather than to design a new one.