Probability modelling of vessel collisions

The safe navigation of ships, especially in narrow shipping waterways, is of the utmost concern to researchers as well as maritime authorities. Many researchers and practitioners have conducted studies on risk assessment for maritime transportation and have proposed risk reduction/control measures accordingly. This article provides a detailed review and assessment of various quantitative risk assessment models for maritime waterways. Eighty-seven academic papers and/or project reports are summarized and discussed. The review then proceeds to analyze the frequency and consequence estimation models separately. It should be pointed out that we further summarize the advantages and disadvantages of frequency estimation models and provide recommendations for their application. From the overview, we find that the quantification of the impact of human error is of great importance and should be considered in future studies. Possible solutions are also proposed in the discussions.

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An overview of maritime waterway quantitative risk assessment models.

A great diversity of organisms modify the physical structure of estuarine and coastal environments. These physical ecosystem engineers – particularly, dune and marsh plants, mangroves, seagrasses, kelps, reef-forming corals and bivalves, burrowing crustaceans, and infauna – often have substantive functional impacts over large areas and across distinct geographic regions. Here, we use a general framework for physical ecosystem engineering to illustrate how these organisms can exert control on sedimentary processes, coastal protection, and habitat availability to other organisms. We then discuss the management implications of coastal and estuarine engineering, concluding with a brief prospectus on research and management challenges.

Physical Ecosystem Engineers and the Functioning of Estuaries and Coasts

This paper aims to estimate Vessel Collision Frequency in the Singapore Strait This frequency is obtained as the product of the number of Vessel Conflicts and the causation probability using the real-time vessel movement data from the Lloyd’s Marine Intelligence Unit (Lloyd’s MIU) database The results show that the container carriers have the highest Vessel Collision Frequency while Roll-On Roll-Off (RORO) and passenger ships have the lowest frequency Tankers cause the highest head-on collision frequency In the Singapore Strait, the most risky overtaking area is between longitudes 103°48′E and 104°12′E The most risky head-on area is between longitudes 103°50′E and 104°00′E while the majority of crossing collisions occur between longitudes 103°50′E and 104°12′E The Vessel Collision Frequency is found to be 1·75 per year in the traffic lanes Currently, westbound traffic in the Strait is more risky than eastbound traffic (the number of westbound collisions in July was 0·0991 while the number of eastbound collisions was 0·0470) Furthermore, the estimated Vessel Collision Frequency during the day is less than that at night The results of this paper could be beneficial for the Maritime and Port Authority of Singapore to further enhance the navigational safety strategies implemented in the Singapore Strait 1 INTRODUCTION The Singapore Strait is a 105 kilometre long strait between the Strait of Malacca in the west and the South China Sea in the east It links one of the largest ports to the rest of the world and has a high density of vessel traffic More than 200 vessels pass through the Strait on a daily basis and this gives an annual throughput of approximately 70,000 vessels, carrying 80% of the oil transported to Northeast Asia, as well as one third of the world’s traded goods including Chinese manufactures, Indonesian coffee etc Although the Singapore Strait is of great importance to the global economy (Wang and Meng, 2011; Qu and Meng, 2012), it is not deep enough for some of the largest vessels (mostly oil tankers) The Strait also has substantial sections of narrower and shallower shipping lanes At Philips Channel, it narrows to 2·8 kilometres wide, with 2·1 kilometres in the shipping lanes, creating one of the world’s chokepoints Therefore, the navigational safety of vessels through the

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Vessel Collision Frequency Estimation in the Singapore Strait

Nourishing the shoreface: observations and hindcasting of the Egmond case, The Netherlands

Optimal selection of energy efficiency measures for energy sustainability of existing buildings

The Strait of Istanbul is one of the most congested and risky waterways in the world. Navigation patterns have been investigated using Automatic Indentification System (AIS) data collected over a long period. 1·5 billion AIS messages, gathered over a year from 309,000 moving vessels in the Strait were stored in a Structured Query Language (SQL) database. Grid-based analysis is used to track the time, number, position, type, dimension, heading, speed and course over ground of ships. Local traffic, whose effect on maritime risk has often been neglected, is found to dominate transit traffic by a ratio of eight to one. Vessel distributions indicate that the most common lengths of vessels are 100 m and 170 m. Draught analysis shows a net transfer of goods from north to south. Southbound vessels are more likely to exceed the enforced speed limit due to predominant currents. Courses indicate that the local traffic strongly affects navigation patterns, especially at sectors with sharp turns. All these results help to understand the navigation patterns of ships and give the necessary input to assist in predicting maritime risk.

Maritime Traffic Analysis of the Strait of Istanbul based on AIS data

The influence of a large (3.0x106 m3) nearshore berm on a large (4.1xl06 m3) beach nourishment project at Perdido Key, FL, is addressed via a monochromatic, numerical wave transformation model. Two years of post-placement survey data indicate that the nearshore berm, placed at a depth of 6 m with a relief of 1-1/2 m, did not migrate during this time period. Wave model results suggest that the berm influences the beach nourishment project via refraction, but breaking and diffraction effects are not significant. The berm causes wave transformation and leads to zones of wave energy focusing (and corresponding de-focusing) that affect longshore sediment transport rates in the lee of the berm. For a typical wave condition, predicted high-energy regions correlate well with observed erosional areas. The findings indicate the relative importance of project-induced wave transformation that should be considered during the design process for nearshore berm projects.

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Influence of nearshore berm on beach nourishment

This paper presents a stochastic model to examine ship casualties resulting from tanker traffic through narrow waterways. A state-space model is developed to represent the waterway and the location of vessels at a given time. The distribution of surface current at a given location of the waterway, depending on channel geometry, bottom topography, boundary conditions, and wind distribution, is determined. This is followed by determination of the distribution of the angular drift for a vessel traveling at a given location of a waterway. Lastly, the drift probabilities and random arrival of vessels are incorporated into a Markov chain model. Risk measures are obtained by analyzing the time-dependent and steady-state probabilities of the Markov chain. Results show that the expected number of casualties is proportional to the square of the tanker arrival rate. The methodology is presented on an experimental model of a hypothetical narrow waterway.

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Emre N. Otay

Papers

Optimal selection of energy efficiency measures for energy sustainability of existing buildings

Maritime Traffic Analysis of the Strait of Istanbul based on AIS data

Influence of nearshore berm on beach nourishment

Modeling and analysis of vessel casualties resulting from tanker traffic through narrow waterways

Spatial mapping of encounter probability in congested waterways using AIS