## 6 Conclusions  
In this paper, the HADES system is presented. HADES is the first version of a web-based multi-client coordination system to be used by terminal operators, shipping agents, and port authorities that optimizes berth occupancy. The strategy of HADES is to incentivize voluntary time coordination among vessel arrivals to multi-client terminals in order to reduce congestion delays. This is of special interest in liquid bulk terminals, which often do not have the flexibility to allocate arriving vessels into more than one position and quay, in contrast to container-based terminals. The paper describes the reasons for the creation of HADES, motivated by the needs of the Port of Cartagena (Spain) and, arguably, of other liquid bulk ports, and its main design guidelines. Then, the results of a feasibility study to assess the potential benefits of HADES and similar systems is presented when applied to a particular terminal (E010) in the Port of Cartagena. This study is based on an optimization model that is able to jointly optimize both quay allocation and vessel arrival time coordination. This is the main objective of HADES, but it is used in this study to assess the potential theoretical benefits that time coordination can bring by considering different realistic time flexibility windows (6, 12, and 24 h). The results show that time coordination under the flexibility margins quoted as feasible by port terminals can bring significant benefits by reducing congestion delays of between 50% and 90%. Alternatively, such coordination could be used to almost duplicate port occupation (from 30% to 55%), providing the same level of service. These results show the good performance of HADES and validate interest in using temporal stay coordination as a means of reducing anchoring times caused by congestion. Therefore, the direct consequences are an increase in port profitability as ports can increase revenues by hosting a greater number of calls, maintaining the same infrastructure and the same level of service. Both issues have an impact on the economic benefit of the port, its activity, client loyalty, and the attraction of new clients, which will have an indirect impact on society. The studies reported in this paper stimulate future research works based on the performance, user behavior, and feedback of the HADES proof-of-concept, which has been in place since July 2020, once enough data have been collected. For example, a complete system applied to the whole port will generate greater savings provided that more degrees of freedom are evaluated, such as interaction with more docks, dock flexibility with operations that can be performed on more than one dock, potential simultaneous occupation, and calls with several stays at different docks with possible flexibility in their order. The influence of changes in port loading/unloading rates due to pumping systems  
Figure 5: Estimated average congested delay at dock E010. improvements or systems failures could also be considered in temporal coordination. Additionally, HADES is able to naturally accommodate the existence of different service level agreements among terminal operators and shipping companies; these agreements and other constraints result in different flexibilities time windows announced, an input to HADES optimization. In future work, artificial intelligence and machine learning could be tools to implement in the HADES platform to expand the multi-agent platform to other terminals and improve decision making. Conceptualization, P.J., J.M.G.-F., and P.P.-M.; methodology, P.J., J.M.G.-F., and P.P.-M.; software, P.P.-M.; validation, P.J., J.M.G.-F., and P.P.-M.; formal analysis, J.M.G.-F. and P.P.-M.; investigation, P.J., J.M.G.-F., and P.P.-M.; resources, J.M.G.-F.; data curation, P.P.-M.; writing--original draft preparation, P.J. ; writing--review and editing, P.J., J.M.G.-F., and P.P.-M.; visualization, P.J., [PERSON], and [PERSON]; supervision, [PERSON]; project administration, P.J. ; funding acquisition, [PERSON].