Predicting Grounding Frequencies - Revision history

Oferiks at 08:49, 13 May 2012

2012-05-13T08:49:12Z

← Older revision		Revision as of 08:49, 13 May 2012
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	Following Pedersen [25], the grounding scenarios may broadly be divided into four main categories:		Following Pedersen [25], the grounding scenarios may broadly be divided into four main categories:

	{\|~~border~~="~~o" cellpadding="5" cellspacing="0~~"		{\| class="wikitable"
	!Category		!Category
	!Grounding Scenarios		!Grounding Scenarios

Oferiks: /* Lateral Traffic Distribution */

2009-04-05T15:44:59Z

Lateral Traffic Distribution

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	== Lateral Traffic Distribution ==		== Lateral Traffic Distribution ==

	Ships in category I and II, following an ordinary route, are distributed over a transverse section of the waterway (Lateral Distribution) with some probability density function, fi(z) , where index i refers to a ship class and z is the transverse coordinate, see Figure 11:		Ships in category I and II, following an ordinary route, are distributed over a transverse section of the waterway ([[Lateral Traffic Distribution]]) with some probability density function, fi(z) , where index i refers to a ship class and z is the transverse coordinate, see Figure 11:

	[[Image:20090405 Fig11.jpg]]		[[Image:20090405 Fig11.jpg]]
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	Groundings that are caused by a meeting situations where ships may feel forced to give way, which then subsequent may result in grounding, has not been considered. Such a model requires much more advanced modelling than what is implemented at the present stage. Neither have groundings that are caused by a “rudder stuck” failure. In this case the rudder may either go the extreme starboard/port side or it will get stuck in a central position and cause the vessel either to turn in circles or to follow its path.		Groundings that are caused by a meeting situations where ships may feel forced to give way, which then subsequent may result in grounding, has not been considered. Such a model requires much more advanced modelling than what is implemented at the present stage. Neither have groundings that are caused by a “rudder stuck” failure. In this case the rudder may either go the extreme starboard/port side or it will get stuck in a central position and cause the vessel either to turn in circles or to follow its path.


	== Powered Grounding ==		== Powered Grounding ==

Oferiks: /* Drifting grounding */

2009-04-05T15:37:11Z

Drifting grounding

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	== Drifting ~~grounding~~ ==		== Drifting Grounding ==

	The probability of category III (evasive manoeuvres) and category IV (drifting ships) grounding events are today typically found by modification of the traffic distribution along the route. Combining a 98% Gaussian distribution and a 2% uniform distribution performs the modification of the traffic distribution; see e.g. Gluver and Olsen [12] or Karlson et al. [19].		The probability of category III (evasive manoeuvres) and category IV (drifting ships) grounding events are today typically found by modification of the traffic distribution along the route. Combining a 98% Gaussian distribution and a 2% uniform distribution performs the modification of the traffic distribution; see e.g. Gluver and Olsen [12] or Karlson et al. [19].
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	Depending on the area and the vessel drifting speed of the, the captain may decide to drop the anchor to avoid the vessel is drifting on ground. At present the probability of no anchoring is set to 1. In future when more information has been gathered this model will be revised.		Depending on the area and the vessel drifting speed of the, the captain may decide to drop the anchor to avoid the vessel is drifting on ground. At present the probability of no anchoring is set to 1. In future when more information has been gathered this model will be revised.


	== Calculating Total Number of Groundings ==		== Calculating Total Number of Groundings ==

Oferiks at 15:33, 5 April 2009

2009-04-05T15:33:55Z

Show changes

Oferiks at 14:13, 5 April 2009

2009-04-05T14:13:21Z

← Older revision		Revision as of 14:13, 5 April 2009
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	== Introduction ==		== Introduction ==

			Following Pedersen [25], the grounding scenarios may broadly be divided into four main categories, see Figure 10:

			{\|
			I.\|Ships following the ordinary direct route at normal speed. Accidents in this category are mainly due to human error, but may include ships subject to unexpected problems with the propulsion/steering system that occur in the vicinity of the fixed marine structure or the ground.

			\|-II.\|Ships that failed to change course at a given turning point near the obstacle.

			\|-III.\|Ships taking evasive actions near the obstacle and consequently run aground or collide with the object.

			\|-IV.\|All other track patterns than Cat. I, II and III, for example ships completely out of course due to loss of propulsion.
			\|}

			[[Image:20090405 Fig10.jpg\|200px]]

			Figure 10 shows observed grounding locations in a part of the Great Belt in Denmark over a 15-year-period.

			It is seen that most of the grounding events belong to category I and II, but there are also category III and IV groundings which seem to be randomly scattered over the area.

			In formulating a theoretical model for the grounding scenario it is expedient to divide the grounding scenario into powered groundings and drifting groundings. Such division eases not only the frequency assessment but also the pursuing consequence assessment.

Oferiks: New page: == Introduction == {{Theory_Source_PFH}} Category:Theory

2009-04-05T12:36:05Z

New page: == Introduction == {{Theory_Source_PFH}} Category:Theory

New page

== Introduction ==

{{Theory_Source_PFH}}
[[Category:Theory]]