3. Biblioteca itinerante Parque al Barrio
3.2. Viviendo la itinerancia como praxis social
3.2.7. La Brújula: descubriendo el territorio desde los ojos que lo habitan
The frequency models described in the previous chapter calculates the frequencies of the considered scenarios. In the present chapter descriptions are given of the conse- quences if one of the considered accidents occurs.
There is distinguished between various types of ship collisions (front-front, front-side and front-back collisions) and of groundings. Consequences have been estimated for the three consequence types:
• Fatalities
• Property damage • Environmental damage
The consequence model determines the degree of damage according to the list above and transforms the degree of damage into a cost related to the considered consequence. The environmental damage is restricted to address only costs for clearing and clean-up. Thus, no evaluations of long-term economical effect are in- cluded.
Furthermore, it is noted that no considerations to the safety and rescue installations in Øresund are included in the analysis.
The following sections describe the consequence modelling and the subsequent cost evaluation.
9.1
Consequence models
The consequence models are coupled to the frequency models such that input to the consequence models are based on the condition, that a collision or grounding has occurred. Thus, the model inherits the configuration of ship characteristics most likely leading to a collision/grounding. Hence, the consequence model takes the fol- lowing input characteristics given a collision or grounding:
• Ship types
• Ship width, draught and length • Ship velocity
Furthermore, on basis of the above items, the following enters the model:
• Amount of fuel on board the ships (both bunker fuel and stored fuel on tank- ers)
• Bulb (is the ship with or without bulb – this has an influence on the conse- qunce of a collision since this will most likely lead to a damage below sea level end thus increased risk of spillage into the water)
• Hull type (single or double hull – it is assumed that 90% of all oil tankers are double hull type. This has an effect on the amount of spillage following an accident)
• Number of persons on board the ships (varying from 1 person in small ships to many thousands on the large cruise ships)
On basis of these inputs, a model is established to evaluate: • The number of fatalities
• The property damage • Clearing and clean-up costs
All consequence models are shown in Appendix 14 Bayesian network for conse- quence models. The model for collisions is shown in Figure 9-1.
It is seen from Figure 9-1 that the ship characteristics affect the degree of damage to the ship and ends up in three consequences:
• Total damage to persons • Total property damage • Total release size
Total damage to persons is given as the number fatalities in different intervals (0,0- 1,1-3,3-5,….) and a related probability that the number of fatalities occurs.
Total property damage is given as a number of states (none, very small, small, …) and a related probability that the state occurs.
Total release size is given as a number of states (none, very small, small, …) and a related probability that the state occurs.
The interpretation of the states in economical terms is described in the following.
9.2
Consequence cost evaluation
The present section outlines the economical consequence of the considered risk types:
• Fatalities
• Property damage • Environmental damage
9.2.1 Fatalities
The economical consequence of a fatality related to a ship accident is taken directly from Risk Evaluation Criteria, Safedor, ref. [6] where values between 1.5 and 6 mil- lion US$ are mentioned and the value of 3 million USD is proposed. The amount of money for one fatality is on this basis taken as 18 million DKK2.
No risk aversion is taken into account, i.e. the cost of 10 fatalities is ten times the cost of one fatality.
9.2.2 Property damage
The property damage is estimated based on anonymous information from a ship in- surance company regarding the insurance sums in case of ships being involved in accidents.
Distribution functions of the insurance costs for both grounding and collision show, that there is a wide range of costs ranging from many smaller cost to a few very large costs.
The distribution functions for the insurance costs of both collisions and groundings are shown in Figure 9-2.
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 200,000 400,000 600,000 800,000 1,000,000 100 USD Pr o b ab ilit y d is tr ib u ti o n Collisions Groundings
Groundings (incl. zero) Collisions (incl. zero)
Figure 9-2 Probability distributions for the insurance costs of collision and groundings.
It is noted that there is graphs denoted ‘incl. zero’. These graphs represent the acci- dent costs including also the accidents, where no costs are seen. These zero costs are most likely related to accidents where the insurance company havd no expenses, and may not be relevant for the accident.
The average costs for the cost distribution functions shown in Figure 9-2 amount to • Grounding: 276 million DKK
• Collision: 120 million DKK
Information from other sources, Appendix 15 Accident costs in Norwegian waters, indicates lower values than those shown above. Furthermore, it is noted that these costs relates to accidents for a wide range of areas and ship types. It is considered that Øresund differs from the average conditions – especially concerning groundings due to the fact that the bottom in Øresund is mainly sand bottom which makes the consequences of grounding significantly smaller.
In the consequence model, relations between ship type, speed etc. is established such that different damage states are obtained. On basis of the distribution functions in Figure 9-2 and the special conditions related to Øresund, the relations given in Table 9-1 are used in the analysis for property costs.
Damage state Collision cost [DKK] Grounding cost [DKK] Very small 120 000 0 Small 1 200 000 2 760 000 Medium 12 000 000 276 000 000 Large 120 000 000 22 080 000 000 Very large 4 800 000 000 0 Table 9-1 Cost distributions for property costs.
It is noted that each of the damage states in the model is obtained with a given probability depending on the input parameters. Thus, the damage state ‘medium’ does not necessarily reflect the mean value.
9.2.3 Environmental damage
The cost related to clearing and clean-up (environmental damage) is estimated based on information given in Safedor, ref. [6], where an economical cost of 12 700 US$ per spilled ton of oil due to an accident is proposed. Information from accidents shows economical costs ranging from 15 000 DKK pr. tonne to 55 000 DKK pr. tonne.
The value proposed in Safedor, ref. [6] of 12 700 US$ pr. tonne has been used in the present analysis.
The spillage volumes if accidents occur have a large variation. In ref. [14], an aver- age volume of 400 ton spilled oil per accident is used, and in various accident regis- trations in Øresund spillage volumes of between 1000 and 6000 ton are registered, i.e. the Fu Shang Hai and the Baltic Carrier accidents. On this basis, the relations given in Table 9-2 are applied.
Oil spill [tonne] Cost [DKK] Very small 500 19 050 000 Small 1000 38 100 000 Medium 5000 76 200 000 Large 10 000 762 000 000 Very large 25 000 1 905 000 000
Table 9-2 Spillage volumes and corresponding costs
The probability of being in different states is modelled in the Bayesian networks given in Appendix 13 Bayesian network for frequency models and 14 Bayesian net- work for consequence models.