Maintenance dredging in ports and waterways is essential to ensure safe navigation. With increasing regulatory pressure on the maritime sector to reduce exhaust emissions, both dredging contractors and port authorities are seeking effective mitigation strategies. However, accurate emission estimates for maintenance dredging activities are still limited in the literature and often rely on experiential knowledge rather than scientific methodologies. This study suggests a method for estimating emissions and comparing alternative maintenance dredging strategies by quantifying trade-offs between project duration, energy consumption, and emissions. The method integrates vessel characteristics, project specifications, and sediment properties to allow for situation-specific, realistic assessments. A discrete-event simulation is used to evaluate two alternative scenarios, offering insights into the impact of key parameters on vessel selection and overall operational efficiency. The method is demonstrated using a case study of the Port of Ramsgate (UK), where estimated results are compared with real-world data for validation. Finally, the study outlines theoretical and managerial implications and suggests directions for future research.

Navigation locks enable vessel transit between separated water bodies but also induce water exchange, leading to saltwater intrusion. During droughts, operational strategies that limit this intrusion cause vessel delays. Consequently, accurate estimation of the salt intrusion is essential for optimising these strategies. Current analytical lock exchange models, such as the Sea Lock Formulation, are a suitable and computationally efficient option for this purpose. However, the performance of these models relies on scarce gate-status data of the lock operation. To overcome this challenge, we present a novel method integrating the Sea Lock Formulation with the nautical traffic model OpenTNSim to derive time-varying lock operation parameters from accessible vessel data. This approach uniquely enables simultaneous evaluation of mitigation strategies on both saltwater intrusion and traffic performance. Applied to the world’s largest lock at IJmuiden, the model is validated against measured salt concentration and operation records. When forecasting, our method significantly improves the accuracy of the analytical models, reducing long-term salt intrusion errors from (Formula presented) % to (Formula presented) %. This marks a critical advancement toward a systematic exploration of tradeoffs between hydraulic and nautical objectives, enabling, for the first time, integrated lock management strategies that balance hydraulic protection with nautical efficiency in closed waterway systems.

To support a modal shift toward sustainable freight solutions, such as inland waterway transport (IWT), researchers and practitioners require long-term historical data on IWT freight flows. However, such comprehensive time series have been unavailable until now. This study addresses this gap by presenting a harmonized dataset encompassing 50 years (1970–2023) of IWT freight data across Europe, with a focus on the Rhine-Alpine Corridor. The dataset includes transport volumes (in tonnes) and transport performance (in ton-kilometers), classified according to NST-R, NST2007, and CCR nomenclatures. To ensure data continuity and completeness, processing techniques—including imputation and optical character recognition—were applied. The dataset offers valuable insights for researchers, policymakers, and transport planners aiming to comprehend and enhance the role of IWT in Europe’s freight transport landscape.

The increasing amount of activities at sea, including the development of offshore wind parks, result in a more confined space for shipping, requiring the assessment of risk changes regarding nautical safety and the design of potential mitigation measures. The main contribution of this paper is the transparent evaluation of allision probabilities, based on an event-based approach. This enables a structural consideration of conditional probabilities, and supports uniting quantitative and qualitative analyses. The event-based approach allows evaluating the outcomes from various perspectives: scales, conditions, behaviour and dependencies. The analysis outcomes are represented in a concept called “event table”, from which these perspectives can be extracted. Consequently, from this single data structure, insights can be gained ranging from spatial variations of the risk (highly detailed or global patterns), to detailed distinction between the most important influencing factors (varying from vessel type to environmental condition). It is furthermore possible to switch between wind-park specific risks and assessment of operational and strategic risk-mitigating measures for the entire area. The core feature of incorporating multiple perspectives not only allows various views on the safety risks, providing a better understanding of the most important contributing factors, as well as effectiveness of intervention measures. Our analysis shows the added value of additional distance between shipping lanes and wind parks in the spatial design, and we demonstrate how our multi-perspective approach supports the strategic and operational decisions around the availability and deployment of emergency response vessels.

The inland waterway transport sector is facing increasingly stringent legislation to reduce emissions and improve energy efficiency. Speed planning has the potential to provide logistically compliant, energy-efficient, and emission-reducing voyages for inland vessels. However, current speed planning methods do not consider PM and NO_x emissions, nor do they consider alternative power systems to internal combustion engines (ICE) and full electric systems. These omissions have led to a lack of clarity on the impact of speed planning on the emission profile of inland vessels and the impact of alternative power systems on energy consumption. In this paper we propose a validated speed planning method that considers the emission profile (CO₂, PM₁₀, and NO_x) and different engine types for inland vessels in an leg-based speed planning approach while taking into account varying fairway water depth and speed. Through a use case we show that the vessel can achieve a 7.26% energy, 5.37% CO₂ and fuel, 3.85% NO_x, and 6.77% PM₁₀ reduction while maintaining the same arrival time; showing a distinct difference of this method compared to slow steaming. We also find that CO₂, NO_x, PM₁₀, and energy are not directly proportional when making speed adjustments. Finally, we analyze the adverse effects of emission control areas and emission limits on the energy consumption and arrival times of vessels with non-zero emissions propulsion.

Climate change and socioeconomic developments have led to highly stressed estuarine systems in which dissimilar and conflicting stakeholder interests can no longer be satisfied simultaneously, inevitably resulting in trade-offs. Since translating these stakeholder interests into quantifiable performance indicators is challenging, policy and decision-makers are often bound to qualitative trade-off assessments, potentially resulting in suboptimal system interventions. In this paper, we assess the well-known socioeconomic trade-off in estuaries worldwide: port accessibility versus freshwater availability. We consider the severely dry year of 2022 in the Rhine-Meuse Delta, for which we assess the effects of bed level change. To quantify the trade-off, we apply a general framework of performance indicators determined based on models that use the output of a validated hydrodynamic model, including salt transport. Port accessibility was quantified based on vessel waiting times, using a data-driven nautical traffic model. For the performance indicator of freshwater availability, we developed a metric that includes storage capacity. The method resulted in a trade-off curve showing improved freshwater availability and deteriorated port accessibility for decreasing bed level. This trade-off curve provides valuable insights into system interventions in a multidisciplinary setting, being an intuitive visualisation showcasing the (non-monetary) benefits and costs for different stakeholders with dissimilar interests. As the method could be expanded and applied further, this study aids quantitative policy and decision-making.

The native European flat oyster (Ostrea edulis) is an ecosystem engineer providing important ecosystem services, but became nearly extinct from the North Sea due to diseases and overfishing. There's a growing interest to restore these oyster reefs for their valuable contribution in re-establishing a rich ecosystem in the North Sea. In order to reintroduce the flat oyster population, the availability of hard substrate is crucial for initial settlement and reef development. Such substrate is offered by the infrastructure in offshore wind farms, by means of quarried rock placed at the base of the wind turbine foundations and on top of cable crossings to prevent scouring of the seabed. Further anthropogenic disturbances of the seabed are largely restricted, making wind farm areas promising sites for oyster reef restoration. For successful oyster reef initiation, offering a suitable type of substrate for larvae settlement is important. Here, we assess the settlement preference of flat oysters on 9 different types of substrate, by comparing total settlement, spat densities and spat survival. Oyster larvae settlement preference based on the total number of spat per surface area of the substrate was the highest for granite, a rock type conventionally used as scour protection in offshore wind farms. The lowest settlement preference was observed for steel and the biodegradable polymer BESE. The experiments were performed in a spatting pond and in a natural bay to be able to compare spat collection under controlled and natural conditions. Settlement rates in the spatting pond were much higher than in the natural environment, though survival rates were lower. Our results provide insight in the settlement preference of the European flat oyster for different types of substrate under controlled and natural conditions. Knowing these favorable substrates and conditions for oyster larvae settlement allows for the selection of pro-active measures that contribute to flat oyster reef restoration in the North Sea.

Purpose: Maintenance dredging can often hinder port operations resulting in waiting times for seagoing vessels. The purpose of this paper is to investigate the dynamics between maintenance dredging activities and seagoing vessels, specifically focusing on how waiting times can be reduced. Then, the role of selecting different maintenance dredging strategies in reducing these waiting times is outlined. Methods: The study analyzes historical automatic identification system (AIS) data to identify the interaction between maintenance dredging and seagoing vessels and quantify the hindrance periods for the Mississippihaven case study in the Port of Rotterdam, the Netherlands. The trajectories of the vessels are analyzed in a simple case to show how the vessels interact and how the waiting times are quantified. The interactions are checked with the Port of Rotterdam for different port calls to ensure that maintenance dredging was the reason for these delays. Results: By analyzing the AIS data analysis of vessels in a given time window, the dredgers for maintenance work can be identified and their activities within or near the terminal can be determined. In addition, the waiting time of the seagoing vessel caused by the maintenance dredging is quantified at the terminal entrance. Conclusion: The study discusses how the maintenance dredging operations could be improved by adjusting the loading and sailing phases of maintenance dredging and provides some theoretical and managerial insights. Alternative port maintenance strategies to minimize the waiting time caused by the hindrance are also discussed.