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Chemical tanker traffic constitutes a hazard for the environment; large chemical spills caused by, for example, ship–tanker collisions can have catastrophic effects in similar manner to oil spills. For this reason, it is important to have a generalized spill model for chemical tankers, so that the spill size for a given geographical area can be assessed. The spill volume can be used as an indicator of risk in the given area. Furthermore, such a model can be used to analyze the possible effects of potential risk-mitigating measures such as requiring wider double hulls for chemical tankers. In this article, a spill model is proposed, which for a given collision scenario can model the penetration, spill probability, and size caused by a ship striking a chemical tanker. This is done using finite element method, MATLAB, and statistical metamodels with ship particulars extracted mainly from automatic identification system data from the Gulf of Finland. [ABSTRACT FROM PUBLISHER]

Abstract: Maritime traffic poses various risks in terms of human, environmental and economic loss. In a risk analysis of ship collisions, it is important to get a reasonable estimate for the probability of such accidents and the consequences they lead to. In this paper, a method is proposed to assess the probability of vessels colliding with each other. The method is capable of determining the expected number of accidents, the locations where and the time when they are most likely to occur, while providing input for models concerned with the expected consequences. At the basis of the collision detection algorithm lays an extensive time domain micro-simulation of vessel traffic in the given area. The Monte Carlo simulation technique is applied to obtain a meaningful prediction of the relevant factors of the collision events. Data obtained through the Automatic Identification System is analyzed in detail to obtain realistic input data for the traffic simulation: traffic routes, the number of vessels on each route, the ship departure times, main dimensions and sailing speed. The results obtained by the proposed method for the studied case of the Gulf of Finland are presented, showing reasonable agreement with registered accident and near-miss data. [Copyright &y& Elsevier]

Ship collision is the most common type of accident in the Northern Baltic Sea, posing a risk to the safety of maritime transportation. Near miss detection from automatic identification system (AIS) data provides insight into maritime transportation safety. Collision risk always triggers a ship to maneuver for safe passing. Some frenetic rudder actions occur at the last moment before ship collision. However, the relationship between ship behavior and collision risk is not fully clarified. Therefore, this work proposes a novel method to improve near miss detection by analyzing ship behavior characteristic during the encounter process. The impact from the ship attributes (including ship size, type, and maneuverability), perceived risk of a navigator, traffic complexity, and traffic rule are considered to obtain insights into the ship behavior. The risk severity of the detected near miss is further quantified into four levels. This proposed method is then applied to traffic data from the Northern Baltic Sea. The promising results of near miss detection and the model validity test suggest that this work contributes to the development of preventive measures in maritime management to enhance to navigational safety, such as setting a precautionary area in the hotspot areas. Several advantages and limitations of the presented method for near miss detection are discussed. [ABSTRACT FROM AUTHOR]

Abstract In northern sea areas such as the Baltic Sea and the Arctic, especially in winter conditions, the presence of sea ice frequently necessitates icebreaker assistance operations for vessels navigating in these areas. Icebreaker escort operations are important for ensuring the safety of navigation in these harsh environments. While these operations reduce the overall system risk, studies have shown that specific navigational risks are associated also with escort operations, necessitating appropriate training and operational support for ship crew engaged in these. In this paper, the icebreaker escort operations are investigated, and a ship-following model is proposed, drawing on similarities with the car following phenomenon. This ship-following model accounts for the necessity of keeping an appropriate safety distance to avoid collision, as well as for the effects of sea ice on the operation. Its main intended use is for implementation in maritime simulators, providing a realistic environment of operational conditions for training ship crews. As a first approximation, the model accounts for the ice condition by the average ice thickness, while the safety speed constraint is relative to the vessel's ability of navigating in ice. The model parameters are calibrated using empirical data of icebreaker escort operations. Case studies are executed, showing good agreement between the simulation model and real-world operational conditions. Highlights • A ship-following model for icebreaker escort operations is proposed. • Safety distance and the effects of sea ice on the operation are accounted for. • Main intended use of the proposed model is for implementation in maritime simulators. • The model parameters are calibrated using empirical data of icebreaker escort operations. • Case studies show good agreement between the simulation model and real-world operations. [ABSTRACT FROM AUTHOR]

Maritime accidents have the potential to cause significant financial loss, injury, and damage to the environment. One approach to investigating maritime safety is to focus on near misses, that is, situations which did not lead to an accident but where an accident was narrowly avoided. Based on the principles of the traffic conflict technique, which ranks traffic encounters through a conflict severity hierarchy, this paper proposes a novel model for screening maritime traffic data for near miss ship-ship encounters, particularly for open sea and coastal restricted sea areas. Compared to previous methods, the proposed method has a greater specificity, leaving fewer possible near miss cases to be assessed by navigational experts in a contextualised traffic setting. This is achieved by including the effect of ship size through a ship domain, and by better accounting for the criticality of the encounter direction through the Minimum Distance To Collision concept compared to earlier proposed models. The factors included in the model and their relation are based on expert judgments and using knowledge from previous studies. Model parameters are derived from AIS data points from a reference encounter situation dataset. The developed model has been applied to traffic data from the Northern Baltic Sea. The model is subjected to a number of validity tests, the results of which suggest that the model is adequate for ranking and prioritizing encounters for further assessment in an expert judgment phase to identify near misses. Thus, it establishes a method to enable subsequent research into the validity of near miss information to make statements of maritime safety in relation to collision accidents. [ABSTRACT FROM AUTHOR]

• Review of 20-year maritime fleet risks and accident trends. • Survey of systems driven intelligent decision support methods. • Current static methods are costly and overlook real conditions. • Emerging methods enhance collision and grounding prevention. • Future of maritime safety: AI, big data, and rapid prediction. Despite advancements in science and technology, ship collisions and groundings remain the most prevalent types of maritime accidents. Recent developments in accident prevention and mitigation methods have been bolstered by the rise of autonomous shipping, digital technologies, and Artificial Intelligence (AI). This paper provides an exhaustive review of the characteristics of fleets at risk over the past two decades, emphasizing the societal impacts of preventing collisions and groundings. It also delves into the key components of decision support systems from a ship's perspective and undertakes a systematic literature review on the foundations and applications of systems-driven decision support methods for ship collision and grounding prevention. The study covers risk analysis, damage evaluation, and ship motion prediction methods from 2002 to 2023. The conclusions indicate that modern ship science methods are increasingly valuable in ship design and maritime operations. Emerging multi-physics systems and AI-enabled predictive analytics show potential for future integration into intelligent decision support systems. The strategic research challenges include (1) underestimating the impacts of real operational conditions on ship safety, (2) the inherent limitations of static risk analysis and finite numerical methods, and (3) the need for rapid, probabilistic assessments of damage extents. The demands and trends suggest that leveraging big data analytics and rapid prediction methods, underpinned by digitalization and AI technologies, represents the most feasible way forward. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a study leading towards a new definition of a ship–ship collision criterion, allowing further estimation of the probability of maritime accidents is conducted. The criterion is called the minimum distance to collision (MDTC) and reflects the shortest distance between two ships at which they must take evasive actions to avoid a collision. The new criterion is evaluated by means of a series of simulations using a ship motion model for a range of ship types, courses and speeds and thus its dynamic nature is recognised. It addresses the crossing type of ship–ship encounter. Additionally, this study defines a causation factor, which quantifies the proportions of cases in which two ships meeting each other end up having a collision. The causation factor is obtained in the course of maritime traffic analysis and accidents statistics. A comparative method is applied and the causation factors are determined for three different meeting types (head-on, crossing and overtaking). The causation factors obtained are valid for the MDTC model, chosen location and prevailing traffic conditions. The major factors affecting the MDTC criterion and relevant steps in the evaluation of the causation factors are described and discussed in the paper. [Copyright &y& Elsevier]

The dynamic response of ships following grounding and collision accidents may be influenced by structural topology as well as operational and environmental conditions. Traditionally, the consequences of such events may be assessed by crude empirical methods or laborious experiments. Computational methods offer a useful alternative in terms of accurately capturing crushing mechanisms also accounting the influence of surrounding water. This paper presents a benchmark study that compares the structural dynamic response by explicit nonlinear FEA approaches and the semi-numerical super-element method. Simulations for typical accident scenarios involving passenger ships confirm that implementing the influence of hydrodynamic restoring forces in way of contact may be useful for either collision or grounding. Yet, for grounding scenarios, the damaged area resulting from analytical simulations appears to be sensitive to the failure strain values adopted to model the rupture of the ship bottom floors. • Explicit nonlinear FSI methods utilising FEA and super element methods are benchmarked for various scenarios. • Structural topology, operational scenarios and environmental conditions influence accidental wave loads uncertainties. • Hydrodynamic restoring forces affect both collision or grounding loads. • In grounding breach sizes are sensitive to failure strain values. • Comparisons demonstrate that the super element method may be used for regulatory development. [ABSTRACT FROM AUTHOR]

• The technique using non-accident critical events as surrogate indicators to assess waterway risk has attracted much attention. • A critical review of the academic literature on non-accident critical events detected from AIS data is presented. • The analysis focuses on the definition, accident theory, measurement, model use, and validation of non-accident critical events. • Results indicate variations in conceptual basis and implementation, and a lack of extensive validation. The safe navigation of ships is of high societal concern. A promising approach for analyzing waterway risks is using non-accident critical events as surrogate indicators of collision accidents. These are typically detected in data from the Automatic Identification System (AIS). Recognizing the significant interest in this approach, this article provides a review and analysis of methods based on the detection of non-accident critical events from AIS data, which aim to provide insight into maritime waterway risk. Considering also recent calls for increased focus on foundational issues in risk research and safety science, each method in the literature is critically reviewed based on five questions: How are non-accident critical events defined? What is the accident-theoretical basis of the method? How are non-accident critical events ranked? How is the method used? To what extent has the method been validated? Based on the results, it is concluded that focus is needed to build evidence of the validity of the models' results, if these are to be effectively used for waterway risk analysis. As a prerequisite, more focus is needed on how exactly non-accident critical events are defined, and what factors are involved in the relation between their occurrence and accident involvement. [ABSTRACT FROM AUTHOR]

The capability of an icegoing ship to break out from an ice channel is a main index of its manoeuvrability in ice. Breakout is necessary if a ship needs to change its course when sailing in an ice channel. Breakout can also be used as an evasive action to avoid collision with the leading ship in emergencies during escort and convoy. Although the ice channel breakout test is documented in ITTC guidelines as a standard manoeuvring test, little data is available on the performance of icegoing ships in this context. This paper presents model-scale tests carried out at Aalto Ice Tank with a double-acting vessel with podded propulsion. Parameters including ice thickness and strength, ice channel width, initial speed and propulsive settings are varied between the tests to examine their influence on the capability and distance to break out from ice channels. In addition, stopping tests by reversing propeller revolution were conducted in ice channels to benchmark the breakout operation as an option to avoid collision. The test results reveal the influence of multiple factors on the ship's channel-breakout capability, including channel width, shaft power, initial speed, as well as thickness and strength of ice. With additional complementary numerical simulations at high speeds, it is found that for collision avoidance braking is more efficient at low speed and breakout at high speed. Recommendations on breakout test in model scale are given based on the lessons and experience learnt from the experiments. • Ice channel breakout model-scale tests were carried out at Aalto Ice Tank. • Numerical simulations were simulated to compare with and supplement model tests. • Parameters are varied to study their influences on the ice channel breakout capability. • Ice channel braking is more efficient at low speeds and breakout at high speeds for collision avoidance. • Recommendations on ice channel model-scale tests are given. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Collision accidents between icebreaker and assisted ship in ice-covered waters are investigated. • The collision risk factors are identified and classified according to HFACS-SIBCI model. • The fault tree model is proposed to analyze collision risk factors under icebreaker assistance. • Risk Control Options (RCOs) are formulated to prevent collision accident occurrence in ice-covered waters. Abstract With the global warming and a large amount of sea ice melting, the available Arctic Sea Route has greatly enhanced the value of Arctic shipping. Ship operations under icebreaker assistance have become an essential way to facilitate the safe navigation of merchant vessels sailing through the Arctic Sea Route in ice-covered waters, but they can also put the crew and the ship in danger caused by a possible collision between the assisted ship and the icebreaker. In this paper, a dedicated Human and Organizational Factors (HoFs) model of ship collision accidents between an assisted ship and an icebreaker is developed and analyzed with the aim to identify and classify collision risk factors. First, a modified model of the Human Factors Analysis and Classification System (HFACS) for collision accidents between a ship and an icebreaker in ice-covered waters is proposed, which helps to analyze ship collision reports. Then, a Fault Tree Analysis (FTA) model is utilized to analyze the fundamental collision risk factors according to the statistical analysis of accident reports and expert judgments based on the HFACS-SIBCI model. Finally, qualitative analysis is carried out to analyze collision risk factors under icebreaker assistance, where Risk Control Options (RCOs) are formulated. An important guidance for the risk control of ship collisions during icebreaker assistance in ice-covered waters is provided for lawmakers and shipping companies. [ABSTRACT FROM AUTHOR]

Abstract: Maritime accidents involving ships carrying passengers may pose a high risk with respect to human casualties. For effective risk mitigation, an insight into the process of risk escalation is needed. This requires a proactive approach when it comes to risk modelling for maritime transportation systems. Most of the existing models are based on historical data on maritime accidents, and thus they can be considered reactive instead of proactive. This paper introduces a systematic, transferable and proactive framework estimating the risk for maritime transportation systems, meeting the requirements stemming from the adopted formal definition of risk. The framework focuses on ship–ship collisions in the open sea, with a RoRo/Passenger ship (RoPax) being considered as the struck ship. First, it covers an identification of the events that follow a collision between two ships in the open sea, and, second, it evaluates the probabilities of these events, concluding by determining the severity of a collision. The risk framework is developed with the use of Bayesian Belief Networks and utilizes a set of analytical methods for the estimation of the risk model parameters. Finally, a case study is presented, in which the risk framework developed here is applied to a maritime transportation system operating in the Gulf of Finland (GoF). The results obtained are compared to the historical data and available models, in which a RoPax was involved in a collision, and good agreement with the available records is found. [Copyright &y& Elsevier]

Collision accidents may lead to significant asset damage and human casualties. This paper introduces a direct analysis methodology that makes use of Automatic Identification System (AIS) data to estimate collision probability and generate scenarios for use in ship damage stability assessment. Potential collision scenarios are detected from AIS data by an avoidance behaviour-based collision detection model (ABCD-M) and the probability of collision is estimated in various routes pertaining to a specific area of operation. Damage extents are idealised by the Super – Element (SE) method accounting for the influence of surrounding water in way of contact. Results are presented for a Ro - Pax ship operating from 2018 to 2019 in the Gulf of Finland. It is confirmed that collision probability is extremely diverse among voyages and the damages obtained correlate well with those adopted by the UN IMO Regulatory Instrument SOLAS (2020). It is concluded that the method is by nature sensitive to traffic features in the selected case study area. Yet, it is useful for the evaluation of flooding risk for ships operating in real hydro-meteorological conditions. • We present a direct method for damage stability assessment in real conditions. • Collision probability is estimated in various routes. • Probabilistic damage extends are evaluated by the Super – Element (SE) method. • Damages correlate to those adopted by IMO SOLAS. • The method could apply within the context of the safety case approach. [ABSTRACT FROM AUTHOR]

• A risk perception-based ship domain is proposed. • This domain accounts for the timing of ship taking evasive maneuvering. • The size of this domain is empirically determined over ship encounters in AIS data. • Available maneuvering margin is employed as a proxy for risk perception. • The size of the domain varies with ship size, ship length and COLREGs identity. This paper introduced a new ship domain concept and an analytical framework. The ship domain takes the point of the ship's first evasive maneuver as a basis and correlates it with the navigator-perceived collision risk level. The first evasive maneuver of a ship is detected based on the ship turning point identification and ship intention estimation. The available maneuvering margin (AMM) is utilized as a proxy to measure the perceived collision risk by the navigator. Interpreting the first evasive maneuver in terms of this AMM over a large sample of vessel encounters taken from automatic identification system (AIS) data finally enables an empirical estimation of the size of this ship domain. The method is applied to AIS data in the Northern Baltic Sea, and separate ship domains are constructed for the give-way and stand-on vessels with different maneuverability characteristics. Compared to the existing proximity-based ship domain, this ship domain explicitly incorporates the dynamic nature of the encounter process and the navigator's evasive maneuvers. Several advantages of this proposed ship domain concept and limitations of the presented modeling approach are discussed. Finally, possible future applications are explained, including waterway safety assessment and navigational decision support systems to reduce ship-ship collision risk. [ABSTRACT FROM AUTHOR]

• We propose a Machine Learning method for the evaluation of collision risk • The method makes use of AIS and hydrometeorological big data records • Ship trajectories are clustered in various routes in the Gulf of Finland • A Collision Detection Model is applied to identify potential collision scenarios • The method can be useful for operational decision making This paper presents a big data analytics method for the evaluation of ship-ship collision risk in real operational conditions. The approach makes use of big data from Automatic Identification System (AIS) and nowcast data corresponding to time-dependent traffic situations and hydro-meteorological conditions respectively. An Avoidance Behavior-based Collision Detection Model (ABCD-M) is introduced to identify potential collision scenarios and Collision Risk Indices (CRIs) are quantified when evasive actions are taken for each detected collision scenario in various voyages. The method is applied on Ro-Pax ships operating over 13 months of the ice-free period in the Gulf of Finland. Results indicate that collision risk estimates may be extremely diverse among voyages, and in 97.5% of potential collision scenarios the evasive actions are triggered only when risk is at 45% or more of its maximum value. The overall CRI for ships operating over the given area tends to be lower for adverse hydro-meteorological conditions. It is therefore concluded that the proposed method may assist with the (1) identification of critical scenarios in various voyages not currently accounted for by existing accident databases, (2) definition of commonly agreed risk criteria to set off alarms, (3) the estimation of risk profile over the life cycle of fleet operations. [ABSTRACT FROM AUTHOR]

Analysis of the dynamic response of ships in accident scenarios requires a realistic idealisation of environmental and operational conditions by multi-physics models. This paper presents a procedure that simulates the influence of strongly coupled FSI effects on the dynamic response of ships involved in typical collision and grounding events. Our method couples an explicit 6-DoF structural dynamic finite element scheme with a hydrodynamic method accounting for (a) 6-DoF potential flow hydrodynamic actions; (b) the influence of evasive ship speed in the way of contact and (c) the effects of hydrodynamic resistance based on a RANS CFD model. Multi-physics simulations for typical accident scenarios involving passenger ships confirm that suitable FSI modelling may be critical for either collision or grounding events primarily because of the influence of hydrodynamic restoring forces. • We present an FSI model for assessing ship crashworthiness. • Our model simulates ship evasiveness, seakeeping and hydrodynamic resistance. • An explicit FEA scheme is used to couple structural dynamics and hydrodynamics. • FSI simulations confirm the influence of hydrodynamic restoring forces on dynamic response. [ABSTRACT FROM AUTHOR]

Bridge alarms are a plausible way to reduce the ship collision probability by timely alerting the officer on watch of a conflict. However, there currently are no dedicated methods for alerting a stand-on ship to compensate the unawareness of or inactive response of a give-way ship to dangerous encounter situations. Therefore, this article proposes a collision alert system from the stand-on ship perspective to trigger the stand-on ship's involvement in the conflict elimination. The developed method quantifies the terms of the COLREGs regarding the stand-on ship's responsibility for conflict elimination. The conflict severity is divided into 9 classes based on the ship intention estimation, conflict evolution analysis and COLREGs scrutiny. These are linked with the 4 stages of the encounter process to helps stand-on ship clarify her action responsibilities as per the rules and classify the alert into four levels. The available maneuvering margin of the stand-on ship is considered to improve the accuracy of severity ranking. The results of several case studies in open water with good visibility indicate that the proposed method can support the stand-on ship to correctly understand the rules and to fulfil her duties. • A COLREG-compliant ship collision alert system for the stand-on ship is proposed. • The terms of the COLREGs regarding the stand-on ship's responsibility for conflict elimination are quantified. • Available maneuvering margins of the stand-on ship is considered to improve the severity ranking accuracy. • Conflict severity is divided into 9 classes based on the ship intention estimation and conflict evolution analysis. [ABSTRACT FROM AUTHOR]

The lack of situational awareness is a major cause of ship collisions. Thus, enhancing the situational awareness of the stand-on ship is a key for navigational safety, where the intention estimation of the give-way ship is crucial. According to COLREGs, the stand-on ship is not allowed to take evasive actions until the give-way ship does not take proper actions timely. The stage that needs the stand-on ship to take actions plays as the second protective layer for the ship, which is named as 'Stand-on Ship as Second Line of Defense' (SLoD). A method to estimate the intention of the give-way ship and to trigger SLoD is proposed in this article. Four modules of the proposed method include: "data pre-processing" collects all traffic information and determines the ships' obligations; "action identification" pinpoints the turning points; "action uncertainty" generates a bounded reachable velocity considering the give-way ship's maneuverability; "conflict assessment" judges potential collision by using non-linear velocity obstacle algorithm. Several typical encounter scenarios are simulated to demonstrate the feasibility of the proposed method. The results show that intention estimation of the give-way ship improves the situational awareness of the stand-on ship, which can support the stand-on ship to make collision avoidance decisions. • Improving the situational awareness of the stand-on ship by intention estimation of the give-way ship. • Intention estimation considering dynamics of the give-way ship, action uncertainty and conflict. • A method identifying turning points of the give-way ship based on its trajectory. • Using reachable velocity set to bound the uncertainty of the ship action. [ABSTRACT FROM AUTHOR]