# The Environmental Impact of Inland Empty Container Movements Within Two-Depot Systems
## 1 Introduction  
The container shipping business is an important aspect of the worldwide supply chain's flow of commodities. It is the most efficient and cost-effective method of long-distance transportation of large goods. According to UNCTAD [1], 90% of the world's goods are transported in ocean freight shipping containers. Due to trade imbalances, a substantial proportion of global container transportation consists of empty container movements [2], representing a highly inefficient use of assets. It occurs after a container has been off-loaded and emptied at the end location. Fortunately, a diversity of publications discusses the main reasons behind this problem and how this problem can be managed by using different approaches; see [3, 4, 5]. While much attention has been given to emissions from empty container repositioning in maritime operations, a less visible yet critical issue lies in inland transportation. Furthermore, inland transport systems are heavily engaged in relocating empty containers between depots, terminals, and customers. This process is not only economically inefficient but also environmentally harmful, as these empty movementscontribute substantially to releasing millions of metric tons of CO2 into the atmosphere without generating direct economic value. The International Maritime Organization (IMO, London, UK) aims to bring carbon emissions from the shipping industry down by 40% compared to 2008 levels by 2030 and decarbonize the shipping sector completely by the end of the century [6]. Hence, most shipping companies are under pressure to be committed to the 2030 vision of decarbonization, and all of them are working on green fuels and other ideas for their operations to reduce the environmental burdens. However, achieving these goals requires more than just decarbonizing vessels; it also necessitates addressing inefficiencies in inland container logistics, especially the repositioning of empty containers within two-depot systems. To better analyze this issue, prior studies have categorized empty container repositioning into two main operational domains: maritime and inland. The first one focuses on the movement of containers within the sea freight industry, utilizing available vessel capacity to optimize maritime network operations [7; 8; 9]. The second sub-problem focuses on empty container movements in inland transport systems. It entails optimizing truck routes that originate and terminate at ports, ensuring customer needs are met while complying with operational constraints such as vehicle capacity limits and designated time slots at customer locations [10; 11; 12; 13]. This paper focuses on the inland aspect, emphasizing container repositioning in two-depot systems where truck-based transport dominates [14; 15]. According to [PERSON] et al. [16], empty containers account for roughly 40-50% of all land-based container movements, compared to about 20% observed in maritime container transport. Furthermore, managing the movement of empty containers within inland areas poses a major logistical challenge for shipping companies offering door-to-door transport services. A vast number of empty containers must be relocated between inland storage facilities and terminals to ensure they are reused efficiently and to maintain a stable supply chain [17]. Containers are typically moved from import customers to inland depots and subsequently delivered from these depots to export customers, causing a wide array of operating costs and higher CO2 emissions. As a result, efficient inland repositioning should balance container availability to meet customer demands while also considering environmental sustainability [18; 19; 20]. To address this problem, the paper proposes ABM using NetLogo to describe and optimize the movement of empty containers between two-depot service systems and reduce associated CO2 emissions. The model incorporates key variables such as transportation mode, terminal locations, and emissions output.