Resumen: Nowadays, urban freight transport networks must be environmentally sustainable. As a consequence, collaboration strategies have been implemented as one alternative to enhance the efficiency of the supply chain and to reduce its environmental burden. However, there is a lack of knowledge about how to correctly quantify the environmental impact of collaborative urban freight transport networks. To fill this gap, we present an optimization approach for evaluating the environmental performance of collaborative systems by applying the Overall Greenness Performance (OGP) tool. We illustrate our approach using real data from the city of Bogotá, Colombia. Our results provide insights for shifting towards sustainable freight transportation networks. For example, we quantify savings up to 11% of CO2 emissions after applying collaboration in urban transportation contexts.