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EN
The transition from conventionally manned to autonomous ships is accompanied by the development of enhanced Decision Support Systems (DSS) for navigators. Such systems need to consider interactions among hardware, software, and humans and their potential effects on system performance, which require rigorous testing to verify the system's safe decision-making ability and operational limits. Testing requirements for verification are aimed at 1) assessing the system's reliability and failure handling performance, and 2) integration testing. This work uses the System-Theoretic Process Analysis (STPA) to develop integration tests for a novel DSS. STPA is a structured methodology to identify hazards from multiple sources, including hardware or software failures, system interactions, and human errors. The objectives of the study are to develop and assess the feasibility of integration test procedures based on STPA. The stability monitoring subsystem from the DSS is analyzed as a case study. The results are used to suggest functional and performance integration test procedures.
EN
While a system-theoretic approach to the safety analysis of innovative socio-technical systems gains a growing acceptance among academia, safety issues of Maritime Autonomous Surface Ships (MASS) remain largely unexplored. Therefore, we applied a System-Theoretic Process Analysis to develop and analyze a preliminary model of the unmanned shipping system in order to elaborate safety recommendations for future developers of the actual system. Results indicate that certain advancements shall be undertaken in relation to MASS’ software solutions in particular.
EN
An unmanned merchant vessel seems to be escaping from the stage of idea exploration. Once the concept proofs its safety, it may become a part of maritime reality. Although the safety aspect of such a ship has been addressed by a handful of scholars, the problem remains open. This is mainly due to lack of knowledge regarding actual operational circumstances and design of unmanned ships, which are yet to be developed. In the attempt of bridging this gap, the risk analysis associated with unmanned ships needs to be carried out, where all relevant hazards and consequences are assessed and quantified in systematic manner. In this paper we present the results of a first step of such analysis, namely the hazard analysis associated with the unmanned ships. The list of hazards covers various aspects of unmanned shipping originating from both design and operational phases of vessel’s life. Subsequently the hazards and related consequences are organized in a casual manner, resulting in the development of a structure of a risk model.
EN
The rules of road, called COLREGS provide guidelines for navigators onboard ships involved in collision encounter at navigable waters. Specific roles for stand-on and give-a-way vessels are assigned, depending on the phase of the encounter. In this paper we extend further our earlier work on the definition of the boundaries for the third phase of the encounter. The latter is referred to as critical area for an escape maneuver of a stand-on ship, in the situation where the give-way vessel does not take an action. This area is determined with the use of a state-of-the-art, six degree-of-freedom hydrodynamic model of ship motion. Series of simulations are conducted for a specific type of encountering ships applying various rudder angles to perform collision evasive maneuvers. Varying rudder angles reflect the fact, that hard-to-side command cannot always be executed, due to stability conditions of a ship. As a result we obtained a set of areas of various size, depending on the rudder angle used to perform evasive action for the predefined ship loading conditions related to her transverse stability characteristics. These demarcate the boundaries of the third phase of encounter for the standon ship, where other ships on collision courses must not enter. Otherwise a collision cannot be avoided by an action of one ship alone or the ship would have to turn too vigorously causing actual stability related threat.
PL
Prawidła prawa drogi dla statków nawigujących na morzu wynikające z konwencji COLREGS określają wzajemne obowiązki statków. W szczególności w sytuacji przecinania się kursów statków idącychn na zderzenie przypisywane są im obowiązki związane z ustąpieniem drogi oraz z utrzymaniem kursu i prędkości. Obowiązki te są jednak uzależnione od fazy spotkania. W artykule rozwinięte zostały wcześniejsze prace dotyczące określania krytycznego obszaru związanego z trzecią fazą spotkania, gdy statek uprzednio zobowiązany do utrzymania kursu i prędkości jest już zobligowany do podjęcia własnego manewru z powodu nie wykonania swego obowiązku przez statek zobowiązany do ustąpienia drogi. Kształt obszaru krytycznego wynika zarówno z rozmiarów statków, ich właściwości manewrowych, ale także z parametrów statecznościowych, co stanowi nowość w stosunku do dotychczasowego ujęcia zagadnienia. Wykorzystano zaawansowany hybrydowy model hydrodynamiczny określający w toku licznych symulacji ruch statku w sześciu stopniach swobody dla manewru antykolizyjnego wykonanego przy różnych wychyleniach steru. Nie zawsze bowiem wyłożenie steru na burtę jest dopuszczalne z punktu widzenia stateczności i wywoływanego przechyłu. W rezultacie wyznaczono granice obszaru krytycznego dla pełnego zakresu wychyleń steru. Niedopuszczalne jest zbliżenie powodujące wejście statku w obszar krytycznych, gdyż niemożliwe stanie się wówczas uniknięcie zderzenia własnym manewrem bądź przekroczona zostanie krytyczna wartość kąta przechyłu, co jest niebezpieczne dla statku, pasażerów i przewożonego ładunku.
EN
Evasive action in ship-ship encounter has to be carried out on time and in line with the international convention on collision regulation – COLREG. The convention not only includes a set of rules defining types of relations between encountering ships but also indicates appropriate action to be taken in a given encounter. One of such encounters is crossing, where, in case of a collision situation, a give-way ship has to take an appropriate action in due time. However, a stand-on vessel is also given an opportunity to manoeuver, if it is made clear to her that the other ship is not fulfilling her obligations. However, it is difficult to specify, at which point in time in the course of an encounter, the stand-on ship has to take an action in order to avoid collision. It is understandable, as this parameter depends on numerous factors, both endogenous (e.g. ship characteristics, her maneuverability), and exogenous (e.g. type of encounter, weather conditions). Therefore in this paper we make an attempt towards the definition of the critical area for a maneuver of a stand-on ship, in the situation where the give-way vessel does not take an action. This is determined with the use of a hydrodynamic model of ship motion, and series of simulations conducted for several types of encountering ships under various conditions. Once determined, the critical area demarcates the no-go area around the own ship, where any other ships on collision courses must not enter. Otherwise a collision cannot be avoided by an action of one ship alone.
EN
Ship traffic is one of the factors that is presented in almost all of the existing grounding models, and is considered as one of the affecting factors on the likelihood of grounding accident. This effect in grounding accident is mostly accepted by the experts as a common sense or simply by just generalizing the ship‐ship collision cases to grounding accidents. There is no available research on the actual causal link between the ship traffic and grounding accident in the literature. In this paper, authors have utilized the statistical analysis on historical grounding accident data in the Gulf of Finland between the years 1989 and 2010 and the AIS data of the same area in year 2010, as the source of ship traffic data, to investigate the possible existence of any correlation between the ship traffic and the grounding accident. The results show that for the studied area (Gulf of Finland) there is no correlation between the traffic density and the grounding accident. However, the possibility of the existence of minor relation between the traffic distribution and grounding accident is shown by the result. This finding, however, needs further investigation for more clarification.
EN
Although ice navigation has received substantial attention over recent decades, there is still no known modelling technique to predict ship’s speed in a dynamic ice field. This paper introduces probabilistic, data-driven models that predict a ship’s speed and the situations where a ship is probable to get stuck in ice based on the joint effect of ice features, such as the thickness and concentration of level ice, ice ridges, rafted ice, and ice compression. To develop the models, the data from the Automatic Identification System about the performance of a selected ship was used, an ice forecast model was utilized to deliver information about the ice field and the links between the ice conditions and ship movements were established using Bayesian learning algorithms. The case study presented in this paper considers a single and unassisted trip of an ice-strengthened bulk carrier between two Finnish ports in the presence of challenging ice conditions, which varied in time and space. The obtained results show good prediction power of the models, which is on average 80% for predicting the ship’s speed and above 90% for predicting cases where a ship may get stuck in ice. We expect this new approach to facilitate the safe and effective route selection problem for iceinfested waters where the ship performance is reflected in the objective function.
PL
Pomimo, iż żegluga w lodach pozostaje tematem wielu opracowań naukowych, tematyka modelowania zachowania statku w dynamicznym polu lodowym, zwłaszcza w obecności zjawiska kompresji pokrywy lodowej, pozostaje wciąż kwestią otwartą. W artykule przedstawiono dwa probabilistyczne modele, pierwszy szacujący prędkość statku w polu lodowym oraz drugi określający warunki lodowe w których statek może spodziewać się całkowitej utraty prędkości (może utknąć w lodzie). Modele stworzono w oparciu o informacje uzyskane z systemu AIS dostarczającego dane o pozycji oraz położeniu statku w odstępie kilkunastu sekund, wykorzystano także szczegółowe informacje o pokrywie lodowej (stopień koncentracji oraz grubość pokrywy lodowej, zwałów lodowych, nawarstwionego lodu oraz poziom kompresji pokrywy lodowej), pochodzące z numerycznego modelu pogody HELMI, opracowanego w Finskim Instytucie Meteorologicznym. W celu określenia zależności pomiędzy zachowaniem statku a warunkami lodowymi wykorzystano Sieci Bayesa oraz dwa typy algorytmów uczenia maszynowego z danych. Uzyskane modele charakteryzuja się wysokim poziomem prognozowania, 80% dla modelu prognozującego prędkość statku oraz 90% dla modelu prognozującego sytuacje utknięcia w lodzie. Przedstawiona analiza dotyczy pojedynczego przejścia statku masowego posiadającego wysoką klasę lodową, pomiędzy dwoma portami w Finlandii. Przedstawione podejście może być wykorzystane przy rozwiązywaniu problemu wyboru trasy optymalnej w dynamicznym polu lodowym.
EN
For safe and efficient exploitation of ice-covered waters the knowledge about ship performance in ice is crucial. Although ice navigation has received substantial attention over recent decades, there is still no known modelling technique to predict ship’s speed in a dynamic ice field. In order to gain an insight into this process, we need to transform the available data into information first. Only then information can be used to develop new knowledge. This paper demonstrates how to transform still data into dynamic information about operation of maritime transportation system in ice-covered waters. For this purpose, the data from the Automatic Identification System about the performance of a selected ship is used along with a numerical ice forecast model describing the ice field in the analysed sea area.
PL
W celu bezpiecznej oraz wydajnej eksploatacji akwenów pokrytych lodem, wiedza o zachowaniu statku w tych warunkach jest niezbędna. Pomimo, iż żegluga w lodach pozostaje tematem wielu opracowań naukowych, tematyka modelowania zachowania statku w dynamicznym polu lodowym, zwłaszcza w obecności zjawiska kompresji pokrywy lodowej, pozostaje wciąż kwestią otwartą. W artykule omówiono dostępne źródła danych, które po odpowiednim przetworzeniu dostarczą informacji, umożliwiającej lepsze zrozumienie procesu nawigacji statku w dynamicznym polu lodowym co pozwoli na modelowanie tego procesu. W artykule podkreślono zasadność przeprowadzenia procesu przekształcenia danych w informację które następnie można wykorzystać w celu uzyskania nowej wiedzy. Na przykładzie pokazano, iż nawet najdokładniejsze dane, nie dostarczą pełnej informacji, jeżeli nie zostaną odpowiednio przetworzone oraz zinterpretowane, co może prowadzić do błędnych lub niepełnych wniosków.
9
Content available On a risk perspective for maritime domain
EN
In the maritime domain, the risk is evaluated within the framework of Formal Safety Assessment (FSA), introduced by International Maritime Organization in 2002. Although the FSA has become internationally recognized and recommended method, the definition, which is adopted there, to describe the risk, seems to be too narrow to reflect properly the actual content of the FSA. Therefore this article discusses methodological requirements for the risk perspective, which is appropriate for risk management in the maritime domain with the special attention to maritime transportation systems (MTS). This perspective considers risk as a set encompassing the following: the set of plausible scenarios leading to an accident, the likelihoods of the unwanted events within the scenarios and the consequences of the events. These elements are conditional upon the available knowledge about the analyzed system, and understanding of the system behaviour, therefore these two are inherent parts of risk analysis, and need to be included in the risk description.
EN
The collision dynamics model is a vital part in maritime risk analysis. Different models have been introduced since Minorsky first presented collision dynamics model. Lately, increased computing capac-ity has led to development of more sophisticated models. Although the dynamics of ship collisions have been studied and understanding on the affecting factors is increased, there are many assumptions required to com-plete the analysis. The uncertainty in the dynamic parameters due to assumptions is not often considered. In this paper a case study is conducted to show how input models for dynamic parameters affect the results of collision energy calculations and thus probability of an oil spill. The released deformation energy in collision is estimated by the means of the analytical collision dynamics model Zhang presented in his PhD thesis. The case study concerns the sea area between Helsinki and Tallinn where a crossing of two densely trafficked wa-terways is located. Actual traffic data is utilized to obtain realistic encounter scenarios by means of Monte Carlo simulation. Applicability of the compared assumptions is discussed based on the findings of the case study.
11
Content available remote Simplified Risk Analysis of Tanker Collisions in the Gulf of Finland
EN
Maritime traffic poses various risks in terms of human casualties, environmental pollution or loss of property. In particular, tankers pose a high environmental risk as they carry very large amounts of oil or more modest amounts of possibly highly toxic chemicals. In this paper, a simplified risk assessment meth-odology for spills from tankers is proposed for the Gulf of Finland, for tankers involved in a ship-ship collision. The method is placed in a wider risk assessment methodology, inspired by the Formal Safety Assess-ment (FSA) and determines the risk as a combination of probability of occurrence and severity of the consequences. The collision probability model is based on a time-domain micro simulation of maritime traf-fic, for which the input is obtained through a detailed analysis of data from the Automatic Identification System (AIS). In addition, an accident causation model, coupled to the output of the traffic simulation model is proposed to evaluate the risk reduction effect of the risk control options. Further development of the model is needed, but the modular nature of the model allows for continuous improvement of the modules and the ex-tension of the model to include more hazards or consequences, such that the effect of risk control options can be studied and recommendations made. This paper shows some preliminary results of some risk analysis blocks for tanker collisions in the Gulf of Finland.
EN
AIS (Automatic Identification System) data analysis is used to define ship domain for grounding scenarios. The domain has been divided into two areas as inner and outer domains. Inner domain has clear border, which is based on ship dynamic characteristics. Violation of inner domain makes the grounding accident unavoidable. Outer domain area is defined with AIS data analyzing. Outer domain shows the situation of own ship in compare with other similar ships that previously were in the same situation. The domain can be used as a decision support tool in VTS (Vessel Traffic Service) centers to detect grounding candidate vessels. In the case study presented in this paper, one type of ship, which is tanker, in a waterway to Sköldvik in the Gulf of Finland is taken into account.
13
Content available remote A Decision Support Tool for VTS Centers to Detect Grounding Candidates
EN
AIS (Automatic Identification System) data analysis is used to define ship domain for ground-ing scenarios. The domain has been divided into two areas as inner and outer domains. Inner domain has clear border, which is based on ship dynamic characteristics. Violation of inner domain makes the grounding acci-dent unavoidable. Outer domain area is defined with AIS data analyzing. Outer domain shows the situation of own ship in compare with other similar ships that previously were in the same situation. The domain can be used as a decision support tool in VTS (Vessel Traffic Service) centers to detect grounding candidate vessels. In the case study presented in this paper, one type of ship, which is tanker, in a waterway to Sköldvik in the Gulf of Finland is taken into account.
EN
Large-scale distributed transportation systems can pose various risks in terms of fatalities, environmental pollution, or loss of property. In particular, accident where a vehicle carrying large number of passengers is involved may pose a high risk with respect to human casualties, moreover it will immediately raise a public and political concern. This is an issue in case of maritime transportation systems (MTS), as the biggest ships nowadays can carry up to 8500 people at once (m/s Oasis of the Seas). Thereby lot of effort has been put to increase safety of ships carrying passengers; however the holistic approach to model and manage the risk existing in the MTS is still missing. This paper makes an attempt to fill this gap, by presenting a data-driven model evaluating risk level in the existing MTS and by introducing a systematic methodology for mitigating the risk. Moreover the MTS operating in the Gulf of Finland under non-ice conditions is addressed, where heavy passenger traffic is observed.
EN
The probability of an accident in transportation systems can serve as a measure of these systems safety or risk, depending on the objective. Therefore numerous methods and models for risk evaluation, with respect to maritime, have been developed. However, these models are either too simplified, allowing relatively fast analysis but very often missing the substantial links among the model variables, or they are too slow for effective analysis, due to computational complexity, not necessarily being backed-up with the complexity of the model itself. Thereby, this paper introduces a novel method evaluating the probability of ship-ship collision in the maritime transportation system focusing on the open sea collisions, applying the queuing theory in the simulation model. The model allows relatively fast prediction as it focuses on the specific events (e.g. accidents), instead of simulating the whole traffic. To support this hypothesis a case study is presented focusing on a selected element of transportation system in operation.
EN
In this paper, a study on a newly developed geometrical model for ship-ship collisions probability estimation is conducted. Most of the models that are used for ship-ship collision consider a collision be-tween two ships a physical contact between them. The model discussed in this paper defines the collision cri-terion in a novel way. A critical distance between two meeting ships at which such meeting situation can be considered a collision is calculated with the use of a ship motion model. This critical distance is named the minimum distance to collision (MDTC). Numerous factors affect the MDTC value: a ship type, an angle of intersection of ships’ courses, a relative bearing between encountering ships and a maneuvering pattern. They are discussed in the paper.
EN
In this paper a comparative method for assessing a causation factor for a geometrical model for ship-ship collision probability estimation is introduced. The results obtained from the model are compared with the results of an analysis of near-collisions based on recorded AIS data and then with the historical data on maritime accidents in the Gulf of Finland. The causation factor is obtained for three different meeting types, for a chosen location and prevailing traffic conditions there.
EN
The paper addresses selected problems of marine traffic risk modelling, in respect to collision and grounding probability modelling. Two original models are presented, and a case study regarding ships navigating in selected areas of Gulf of Finland in ice free conditions is putting forward. Probability of vessel colliding is assessed by means of Minimum Distance To Collision (MDTC) based model. The model defines in a novel way the collision zone, using mathematical ship motion model, and recognizes traffic flow as non homogeneous process, unlike other existing models. Calculations presented address waterways crossing between Helsinki and Tallinn, where dense cross traffic during certain hours is observed. Risk profile for a certain period of a day is presented. For probability of grounding a new approach is proposed, which utilizes the gravity model, where spatial interactions between objects in different locations are proportional to their respective importance divided by their distance. A ship at a seaway and navigational obstructions may be perceived as interacting objects and their repulsion may be modelled by a sort of gravity formulation.
PL
W artykule przedstawiono wybrane problemy z zakresu modelowania ryzyka w transporcie morskim, w aspekcie kolizji statków oraz wejść na mieliznę. W pracy przedstawiono dwa nowatorskie podejścia do modelowania prawdopodobieństwa wystapienia powyższych wypadków. Model do oceny prawdopodobieństwa kolizji statków definiuje w nowy sposób strefę kolizji, w oparciu o właściwości manewrowe statku oraz jego hydrodynamikę. Intensywność ruchu morskiego na analizowanym akwenie modelowana jest w oparciu o proces niestacjonarny, w przeciwieństwie do istniejących modeli. Model oceny prawdopodobieństwa wejścia na mieliznę wykorzystuje model grawitacyjny, gdzie statek i otaczające go płycizny traktowane są jako masy, wzajemnie na siebie oddziaływujące. Model określa bezpieczny obszar manewrowy dla danego statku i danego akwenu. Analiza ryzyka przeprowadzona została dla dwóch wybranych akwenów w Zatoce Fińskiej. Jako konsekwencje wypadku przyjęto model kosztów, konstruowany w oparciu o dane statystyczne z międzynarodowego fundusz IOPCF, który pokrywa koszty w związku z rozlewem olejowym na morzu.
19
Content available A model for risk analysis of oil tankers
EN
The paper presents a model for risk analysis regarding marine traffic, with the emphasis on two types of the most common marine accidents which are: collision and grounding. The focus is on oil tankers as these pose the highest environmental risk. A case study in selected areas of Gulf of Finland in ice free conditions is presented. The model utilizes a well-founded formula for risk calculation, which combines the probability of an unwanted event with its consequences. Thus the model is regarded a block type model, consisting of blocks for the probability of collision and grounding estimation respectively as well as blocks for consequences of an accident modelling. Probability of vessbl colliding is assessed by means of a Minimum Distance To Collision (MDTC) based model. The model defines in anovel way the collision zone, using mathematical ship motion model and recognizes traffic flow as a non homogeneous process. The presented calculations address waterways crossing between Helsinki and Tallinn, where dense cross traffic during certain hours is observed. For assessment of, a grounding probability, a new approach is proposed, which utilizes a newly developed model, where spatial interactions between objects in different locations are recognized. A, ship at a seaway and navigational obstructions may be perceived as interacting objects and their repulsion may be modelled by a sort of deterministic formulation. Risk due to tankers running aground addresses an approach fairway to an oil terminal in Skoldvik, near Helsinki. [...]
PL
W artykule przedstawiono model oceny ryzyka w transporcie morskim, w aspekcie kolizji statków oraz wejść na mieliznę. W modelu przyjęto jeden typ statków, tankowce do przewozu ropy naftowej, z uwagi na fakt, iż w przypadku wystąpienia kolizji lub kontaktu z dnem statek ten może stanowić bardzo poważne zagrożenie dla środowiska. W pracy przedstawiono dwa nowatorskie podejścia do modelowania prawdopodobieństwa wystąpienia powyższych wypadków. Model do oceny prawdopodobieństwa kolizji statków definiuje w nowy sposób strefę kolizji, w oparciu o właściwości manewrowe statku oraz jego hydrodynamikę. Intensywność ruchu morskiego na analizowanym akwenie modelowana jest w oparciu o proces niestacjonarny, w przeciwieństwie do istniejących modeli. Model oceny prawdopodobieństwa wejścia na mieliznę wykorzystuje model grawitacyjny, który wyznacza bezpieczny obszar manewrowy dla danego statku i danego akwenu. W modelu tym statek i otaczające go płycizny traktowane są jako masy, wzajemnie na siebie oddziaływujące. Obydwa modele wykorzystują dane o ruchu statków zarejestrowane w systemie automatycznej identyfikacji statków (AIS). Analiza ryzyka przeprowadzona została dla dwóch wybranych akwenów w Zatoce Fińskiej. Jako konsekwencje wypadku przyjęto model kosztów, skonstruowany w oparciu o dane statystyczne z międzynarodowego funduszu IOPCF, który pokrywa koszty w związku z rozlewem olejowym na morzu.
EN
Navigational risk assessment is a complex process, which aims to determine the level of safety over the analyzed area. Usually two approaches are used: qualitative and quantitative. Engineers tend to view risk in an objective way in relation to safety, and as such use the concept of risk as an objective safety criteria. Among engineers risk is defined as a product of probability of occurrence of an undesired event and the expected consequences in terms of human, economic and environmental loss. These two components are equally important; therefore appropriate estimation of these values is a matter of great significance. This paper deals with one of these two components: the probability of vessels. collision assessment. A new approach for probability estimation of collision between vessels is presented, rooted in aviation experiences. The presented model for collision frequency estimation takes into account historical traffic data from AIS, generalized vessel dynamics and uses advanced statistical and optimization methods (Monte-Carlo, Genetic Algorithms).
PL
Szacowanie ryzyka nawigacyjnego jest złożonym procesem, którego celem jest określenie poziomu bezpieczeństwa na analizowanym akwenie. Zazwyczaj stosowane są dwa podejścia: jakościowe i ilościowe. Inżynierowie definiują ryzyko jako prawdopodobieństwo wystąpienia niepożądanego zdarzenia oraz wynikających z niego konsekwencji tj. utraty życia ludzkiego, aspektów ekonomicznych oraz zanieczyszczenia środowiska. Te dwa komponenty są w równym stopniu ważne; dlatego odpowiednie oszacowanie wartości ma bardzo duże znaczenie. W artykule zaprezentowano jeden z dwóch czynników: prawdopodobieństwo szacowania kolizji statków. Przedstawiono nowe podejście dotyczące szacowania prawdopodobieństwa kolizji pomiędzy dwoma statkami, które zostało zaczerpnięte z doświadczeń lotnictwa. Opisany model szacowania częstotliwości kolizji bierze pod uwagę dane otrzymane z systemu AIS, uogólnioną charakterystykę dynamiki statku przy użyciu zaawansowanych metod statystycznych i optymalizacyjnych (Monte-Carlo, algorytmy genetyczne).
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