Ship collisions

Statistics of ship collisions and their severity, groundings, etc. 

Typical events that are considered are fire, explosion, ship collision, and the failure of pressurized storage vessels for which historical data established the failure frequencies. Assessment of consequences was based partly on conservative treatment of past experience. For example ilic assessment of the number of casualties from the release of a toxic material was based on past histoiy conditioned by knowledge of the toxicology and the prevailing weather conditions. An altemati. e used fault trees to estimate probabilities and identify the consequences. Credit is taken in this process for preventative measures in design, operation, and maintenance procedures. Historical data provide reliability expected from plant components and humans. 

Ammonia, when released is a toxic gas with little flammability. It is imported by sea into the 14,(XX) tonnes capacity tank at Shell UK Oil where the refrigeration maintains the temperature below the boiling point of the gas (33° C). Three ways were identified whereby several hundred tonnes of liquid ammonia could be released into the river to vaporize and disperse. The worst accident would have an accompanying explosion or fire on an ammonia carrier berthed at the unloading jetty. Next in order of severity is a ship collision and spillage into the river near the unloading jetty. The consequences of a collision between ships occurring within the area but not near the jetty were also calculated. 

The team suggested mitigations. For example, the consequences of an ammonia release could be markedly reduced by a reliable and quick-acting water spray system. The probability of damage due to ship collisions could be reduced by a f tor of five by a speed limit of eight knots. Evacuation of the potentially affected is practicable and effective. 

An explosion in the engine room of an LNG carrying ship berthed at the jetty could release vapor cloud, whose explosion would have serious consequences. No amelioration was suggested by the team. Release of cargo, from ship collision was discounted because of the eight knots speed limit. 

Generally offshore facilities and major process plants onshore represent considerable capital investment and have a high number of severe hazards associated with them (blowouts, ship collisions, line and vessel ruptures, etc.). They normally cannot be easily evaluated with a simple safety checklist approach. Some level of "quantifiable evaluation" reviews are usually prepared to demonstrate that the risk of these facilities is within public, national, industry and corporate expectations. 

Specialized studies are investigations that attempt to verify the ability of a facility to perform effectively during an emergency, generally by mathematical estimates. They are used extensively to justify the necessity or deletion of a safety system. The most common studies are listed below however every facility is unique and may require it s own investigative requirements (e g., for an offshore facility - the potential for ship collisions). For example, for a simple unmanned wellhead... 

Offshore facilities are dramatically different from onshore facilities because instead of being spread out the equipment is segregated essentially into compartments or separated into a complex of platforms. Offshore facilities pose critical questions of personnel evacuation and the possibility of total asset destruction if prudent risk assessments are not performed. A through analysis of both life safety and asset protection measures must be undertaken. These analyses should be commensurate with the level of risk a particular facility represents, either in personnel exposed or financial loss. An unmanned wellhead platform might only require the review of wellhead shut-in, flowline protection and platform ship collisions to be effective, while manned drilling and production platforms may require the most extensive analysis. 

But it may be too late—the whale has been hunted down until only about 100 are left, and the species is now threatened by pollution, oil and gas exploration, and ship collisions. 

Lack of escape routes Persons on board Cyclones/hurricanes Downers and leaners Blowouts Hydrogen sulfide Dropped objects Helicopters Ship collision. 

The main elements of these conditions (21 cases reported out of the 23 treated) are summarized in Table 43.3. The difference between the two types of maritime transport, transport in packaged form (38% of incidents) and transport in bulk (62% of incidents), can be seen in the table. Bad weather conditions and the resulting consequences (13 cases out of 21, 62%) are the main causes of incidents including, in order of importance, ship collisions (5 cases), shipwrecks (3 cases), grounding (3 cases), and loss of cargo during navigation (2 cases). 

An estimate regarding the number of trips to be made by helicopters, work boats, and other forms of transportation is required. The consequence of accidents should be estimated. Assumptions having to do with ship collisions (including pleasure boats that may be present) should be made clear. Factors to consider include the speeds at which colUsions may occur and whether collisions occur while boats are maneuvering or drifting. 

There is a side collision protection consisting of reinforced plates in the hull and deck plating adjacent to the board and longitudinal stiffening plates of the board to protect against ship collision ... 

Pbh = ship collision impact force for head-on collision between ship bow and a rigid object (Section 4.6.1)... 

Ship collision forces are commonly applied as equivalent static loads. Procedures for evaluating dynamic effects when the vessel force indentation behavior is known are included in lABSE (1983), Modjeski and Masters (1984), Larsen (1998), Prucz and Conway (1987,1989), Grob and Hajdin (1996). The AASHTO provisions (AASHTO 2009, 2012) use the following formula for estimating the static head-on ship collision force, Ps, on a rigid pier ... 

Formulas for computing design ship collision loads on a bridge superstructure are given in the AASHTO provisions (AASHTO 2009,2012) as a function of the design ship impact force, Pj, as follows ... 

Larsen, A. and Esdahl, S., eds. 1998. Proceedings of International Symposium on Advances in Bridge Aerodynamics, Ship Collision Analysis, and Operation Maintenance, Copenhagen, Denmark, May 10-13,1998, Balkema Publishers, Rotterdam, Netherlands. 

Larsen, O. D. 1993. Ship Collision with Bridges The Interaction between Vessel Traffic and Bridge Structures, lABSE Structural Engineering Document 4, lABSE-AIPC-IVBH, Zurich, Switzerland. 

National Research Coimcil. 1983. Ship Collisions with Bridges - The Nature of the Accidents, their Prevention and Mitigation, National Academy Press, Washington, D.C. 

Prucz, Z. and Conway, W. B. 1987. Design of Bridge Piers Against Ship Collision , Bridges and Transmission Line Structures, (Edited by L. Tall), ASCE, New York, NY, pp. 209-223. 

In final situation the geocontainers will perform as a core material of various protective structures or as independent structure exposed to loading by currents and waves, and other loadings (ice, debris, ship collision, vandalism, etc.). In most cases the geocontainers will be filled by fine (loosely packed) soils. The question is how these structures will behave in practice under various types of external and internal loadings. 

A loss of off-site power should be assumed coincident with any extreme DBEE if a direct or indirect causal relationship cannot be excluded. Particularly, for DBEEs that are expected to affect the entire site and, therefore, to give rise to a potential for a common cause failure mode, a loss of off-site power should be combined with the DBEE. For other events, a loss of off-site power should be assumed if the location of the transmission lines or the switchyard is such that the direct effects on them of the DBEE could cause a loss of off-site power. For external events such as ship collisions and internal events such as fire or anticipated operational occurrences, a coincident loss of off-site power should be assumed if the event could be expected to result in an unplanned turbine trip or reactor trip that would increase the potential for grid instability. 

According to Refe [2, 3], water intakes and UHS structures can be damaged by ship collision, ice or floating debris. Associated phenomena in the... 

The design against ship collision should be capable of providing an adequate level of performance under various environmental conditions and for all the related potential consequences, such as oil spills or releases of corrosive fluids. 

Gucma, L. Przywarty, M. 2007. The Model of Oil Spills Due to Ships Collisions in Southern Baltic Area, Advances in Marine Navigation and safety of sea transportation. Edited by Adam Weintrit, The Nautical Institute, Gdynia. 

In second scenario, probabilities of ship collision alert, occurrence of high, low or negligible risk of collision are equal equivalently ... 

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