## 1 Introduction  
Organizations are facing considerable challenges dealing with performance, efficiency and economy. Dealing with that, they continuously improve their products and services to satisfy demands/customers, make a profit, use innovation, etc. Therefore, a collaboration becomes necessary to share activities, knowledge and services. Moreover, cities should improve their flows in urban areas due to the growth of traffic jams. These generate congestion, noise and pollution problems. Urban logistics is defined as the management of all movements in urban areas [1]. The transport of goods in urban areas has continued to increase due to the increasing number of residents and the emergence of new types of deliveries (e.g., e-commerce, home delivery, etc.). Improving urban logistics becomes necessary to improve the life quality of residents, as well as the attractiveness of cities. For this reason, urban logistics has received growing attention in recent years in order to guarantee sustainability with collaborative models in modern cities [2]. Many attempts have been made to improve logistics flows in urban areas, particularly the urban distribution center (UDC) classified as city terminals. UDC, also known as the urban consolidation center (UCC), is a specialized logistic platform, which concerns deliveries in urban areas. Here, deliveries are consolidated before being shipped for last mile distribution. The objective is to optimize delivery itineraries, to pool resources, to reduce pollution and congestion [3; 4; 5]. Consequently, the work of these UDCs depends on the functioning of their components such as vehicles, software systems, etc. However, a failure of one component may reduce the delivery rate of these platforms. UDC has been created in many European capitals and cities. The success and benefits of UDCs depend on the following factors and their features: customers (location, parking availability, etc. ), transportation (means of transportation, availability, number of drivers, number of deliveries, availability of depots, etc. ), UDC (location, size, capacity, type of vehicle, etc.) and urban areas (size, traffic, type of street, etc.) [6]. However, these UDCs present some of disadvantages such as high operational cost, difficulties in managing the wide range of goods being moved and the loss of a direct relationship between suppliers and customers [7]. We have used this solution in a research study conducted within a collaboration between Metz city through the Metz Metropole development agency and our research laboratory in France to make sure that Metz city will play a key role in sustainable development [8]. We ran a three years' project in order to minimize congestion in the city; to improve the quality of life for residents; and to minimize pollution generated by the transport of goods. At the first stage, we mainly focused on optimizing goods delivery by presenting a diagnosis of the current state and, then, proposing a solution for the creation of a new urban distribution center; this solution has been analyzed by our tool simulator [9]. However, the first results and the development are constrained by the scenario context where data and variables are predefined. A second iteration of this case study will focus on this dynamic aspect in order to foster UDCs' collaboration. Therefore, we investigate the variability of the capacity due to non-availability or the degradation of the system. This is due to a lack of staff during vacation, random failures, planned preventive maintenance actions, etc. In this paper, we believe that a good coordination between maintenance and distribution policies will deal with this issue by defining good planning for UDC to organize distributions and maintenance actions. Furthermore, a collaboration between different UDCs located near the allocated urban area can be more efficient to satisfy customers in urban areas in time. This collaboration is necessary due to the growing urban population.