Precautionary Area Research Articles

Collision risk assessment for ships’ routeing waters: An information entropy approach with Automatic Identification System (AIS) data

The ship's routing was adopted to organise marine traffic flow and reduce the risk of collision between ships in crowded waters. With the expansion of the world's fleet, ship traffic in shipping bottleneck and chokepoint areas became more and more busy and complex creating serious challenges for navigational safety. Therefore, quantitative collision risk assessment is significantly important for the ships' routeing waters. In this paper, the information entropy method which integrates the K-means clustering based on Automatic Identification System (AIS) data is introduced to quantitatively evaluate the collision risks in the ships' routeing waters. As a case study, the information entropy of Courses Over Ground (COG) for Ningbo-Zhoushan Port (the largest port in the world since 2009) is calculated by using historical AIS data. Then the K-means clustering is used to group the bytes of information entropy of the different legs in the shipping route. We find that in Ningbo-Zhoushan port Precautionary Area (PA) 2, 4 and 7 are the highest risk legs; PA 1, 5 and 6, Traffic Separation Scheme (TSS) 16, and 17 are medium-high risk areas. Therefore, ship collision risk prevention measures should be prioritised in those legs. Our contributions provide a novel approach to quantitatively assess ship collision risks in busy waters.

PROBABILITY ASSESSMENT OF CROSSING SITUATION IN SUNDA STRAIT

The new routeing measures in Sunda Strait, that consists of traffic separation scheme (TSS), precautionary area (PA), and inshore traffic zones (ITZ), have been implemented since July 2020. The Automatic Identification System (AIS) data is utilized to understand the traffic pattern in this area. One dataset before and one dataset after the implementation of TSS is then converted into a vessel trip database. Eight vessel courses, two positions, and seven crossing zones are determined from the density plot to categorise the vessel trips. This study introduced a different perspective to assess the crossing situation by using three point-of-views to calculate the probability, namely crossing zone basis, course basis, and vessel type basis. The analysis result shows that the crossing situation is mostly occurred in the precautionary area of the new routeing measure.

Improving Near Miss Detection in Maritime Traffic in the Northern Baltic Sea from AIS Data

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.

Synergetic System for Water Body Detection in Coal Mine: A Case Study

Detection of water yield property is one of the most important tasks for mine water control. Because of low reliability of a single water detection method, it is necessary to find an effective water detection system. In this study, we established a circulatory system for water detection (CSWD) and analyzed working principles of each module of the system. The system was then tested in a China coal mine, and the detailed arrangement of the system was discussed. The geophysical detecting results show that there were three abnormal areas with abundant water body (i.e. safe area I, dangerous area II and potentially dangerous area III). The possibility of those areas initiating water hazards varied a lot. The precautionary and danger areas were verified by field drilling. The drilling results indicate that the amounts of water in most holes of areas II and III were large and the largest water amount reached approximately 63 m3/h. Sites occurring of water inrush accorded well with the detection results using the CSWD, indicating that the CSWD is effective and reliable in detecting areas with potential water hazards.

Automatic Identification System-Based Approach for Assessing the Near-Miss Collision Risk Dynamics of Ships in Ports

Vessel risk analysis is critical for safe ship navigation and maritime safety management. Near-miss collisions by ships comprise an significant risk, which may be complicated by factors, such as the ship conditions, waterway environment, and driving behavior of any ships encountered. Previous studies have rarely considered how to automatically and adaptively estimate the risk of near-miss collisions for different situations, particularly in port areas. In this paper, we propose an automatic identification system-based approach for adaptively calibrating near-miss collision risk model and assessing a ship's near-miss collision risk by using the vessel's speed and course patterns to obtain a robust estimate of the collision risk. Six measures are employed to determine the hierarchical geographical distribution of the near-miss collision risk for ships in port areas and to identify the high-risk areas. Some predicted high-risk areas were validated as official precautionary areas in the Xiamen Port area. All predicted areas may help the port administration to plan monitoring areas to ensure safe traffic flow in the port.

Multi-object-based Vessel Traffic Scheduling Optimisation in a Compound Waterway of a Large Harbour

In order to investigate the benefits of compound waterways more fully, this study reveals vessel navigational mode and traffic conflicts in a compound waterway through a case analysis, following which a type of simplified prototype of a compound waterway is proposed and three key conflict areas are specified. Based on the three key sub-models of slot allocation for vessels in a waterway entrance, traffic flow conversion of a main and auxiliary waterway in a precautionary area, and traffic flow coordination of division and confluence in a Y crossing area, a vessel traffic scheduling optimisation model is presented, with the minimum waterway occupancy time and minimum total waiting time of vessels as the objective. Furthermore, a multi-objective genetic algorithm is proposed to solve the model and a simulation experiment is carried out. By analysing the optimised solution and comparing it with other scheduling schemes in common use, the results indicate that this method can effectively improve navigation safety and efficiency in a compound waterway.

Ship Domain as a Safety Criterion in a Precautionary Area of Traffic Separation Scheme

Ship Domain as a Safety Criterion in a Precautionary Area of Traffic Separation Scheme

Research of Vessel Traffic Safety in Ship Routeing Precautionary Areas Based on Navigational Traffic Conflict Technique

Recently, a basic pattern of coast seaway system networking has been established in China. As a result, a large number of precautionary areas will be gradually established. Because of the high frequency of ships' encounters and accidents, these precautionary areas have been a weak but important facet of ships' routeing. Navigational Traffic Conflict Technique (NTCT) was introduced to quantitatively evaluate the safety of precautionary areas. Focusing on traffic conflict, the calculation method of navigational traffic conflict points is discussed, and a comparison analysis of the two editions (2002 and 2008) of Yangtze estuary ships’ routeing is performed. Then the automatic acquisition system of navigational traffic conflict data that can be used in the quantitative analysis of the influence degree of a single traffic flow on the whole precautionary area safety is developed, and the left-turning traffic flows of Yangtze estuary ships’ routeing precautionary areas B are taken as an example. This article establishes a foundation for the precautionary area safety analysis system, and provides the decision basis for policy making in optimisation of geometric design and traffic organisation of precautionary areas.

Passage Planning System in Ports: An overview

A conceptual model is proposed to monitor marine traffic through precautionary areas, which can provide us with a systematic control of passage planning in ports. On one hand, vessel traffic control has its special features and is fundamentally different from highway, air and pedestrian traffic control. The existing traffic control systems cannot be simply extended to vessel traffic control without addressing marine traffic features. On the other hand, existing vessel traffic control focuses on one ship or two ships but does not address the flows of marine traffic.

The Establishment of Intelligent Detection Method and Monitoring System for Underwater Target Based on Imaging Sonar

For the practical requirement of underwater safety protection, the conception of target precautionary area is put forward combined with the technical characteristic of imaging sonar and the analysis of small underwater target imaging feature. And a detection method for underwater moving target based on image processing is build up, so that the intelligent detection and recognition of the underwater specific target is realized. Meanwhile, the intelligent detection and monitoring system of underwater target based on imaging sonar is designed and developed with the use of multi-level component-based architecture according to the practical application requirements. The system has obtained remarkable economic benefit in practical use and has good prospects for application.

Cellular Automata Ship Traffic Flow Model Considering Integrated Bridge System

For the purpose of efficiency and safety in marine traffic, and considering that ships have to change lane to move on in case of waterway partial closure caused by a marine work zone or an accidence, a new NaSch ship traffic model considering Integrated Bridge System (IBS) is presented, and then a cellular automata model considering IBS for partial reduction waterway is proposed. By numerical simulation, fundamental diagram and time-space spot diagrams of ship traffic flow and that when accidence happens and recovers are given. At last, a numerical example is forwarded to analyze the effect to waterway transit capacity by precautionary area length and ship arrival rate. The model may be applied in decision-making simulation and increase the transit capacity of waterway.

월미도와 영종도 수로간 아쿠아버스 통항안전관리에 관한 연구

국내 최초로 운항예정인 수륙양용 아쿠아버스의 운항 리스크를 낮추고 안전을 확보하기 위하여 운항예정 해역인 월미도와 영종도간 수로에 대한 자연적환경과 해상교통량을 조사하고, 그들의 위험요소를 분석하였다. 그리고 아쿠아버스의 통항 안전 확보를 위하여 경계수역 지성, 잔용선착장 설치, 운항관리 방안 등을 제안하였다. In order to reduce the management risks of and secure traffic safety of Aqua-bus which will be operated at the channel of Wolmi do and Yungjong-do for the first time in Korea, we investigate maritime traffic and natural environment around the channel, and analyze the factors of risk involved in her operation. We also propose the countermeasure to secure the safety of navigation in her service including precautionary area, exclusive terminal, operation management, and etc.

Assessment of Water Quality After 10 Years of Reclaimed Water Injection: The Nardò Fractured Aquifer (Southern Italy)

AbstractExperimental studies have been carried out in a fractured coastal aquifer of the Salento region (Nardò, Italy), which has been subjected to 12,000 m3/day of treated municipal waste water injected into a natural sinkhole since 1991. The analytical parameters of ground water sampled in 30 monitoring wells in the area down gradient from the sinkhole, taking into account the direction of ground water flow, have been compared before and after injection. The water table mound (1.5 m), the reduction of sea water extent (2 km), and the spreading of injected pollutants were evaluated by means of a mathematical model. The predicted values in the monitoring wells were adjusted to inorganic nitrogen biodegradation using transformation rates developed in laboratory tests. After 10 years, the injection has increased the volume of the available resource for agricultural and drinking water use, without any notable decrease in the preexisting ground water quality. Moreover, to preserve water resources from pollution, the mathematical model allowed the maximum constituent concentrations (standards) in waste water reclamation for recharge to be identified. A precautionary area around the sinkhole was also defined so that withdrawal prohibition could be implemented to avoid risks to human health.