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Consideration of Human Error in Risk Assessment
10

Consideration of Human Error in Risk Assessment

Consideration of Human Error in Risk Assessment

(OP)
German authorities require for the approval of risk assessments about offshore windparks the consideration of human error.  The authorities require the consideration of "normal" operator error (e.g. ship officer fails to read the radar information correctly) as well as negligence or gross negligence (operator sleeps during watch or is drunken). Who can inform me how this topic is handled in risk assessments for chemical or petrochemical plants.

RE: Consideration of Human Error in Risk Assessment

3
We handle this issue as part of a Process Hazard Analysis. The most common method is Hazard and Operability Analysis (HAZOP). We used a similar method (What If/Checklist Analysis) recently to identify the risk of ships in a canal system bumping into a lift bridge. Naturally human error on board and on shore, in control of the lift bridge, was a major part of the analysis.

A typical Cause would be "Bridge operator fails to initiate bridge opening on demand". Consequence would be "collision". Safeguards would include: 1) Ship sounds warning. 2) Ship can initiate sound alarm in bridge control room. 3) etc. Recommendations would be made if the safeguards were judged to be inadequate. The study is carried out by a team. Specialized software is available for such studies. See www.dyadem.com

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
owg
Thank you very much for your repley. But what about negligence or gross negligence?

RE: Consideration of Human Error in Risk Assessment

We don't think it is helpful to distiguish among error, negligence, or gross negligence. It just matters that we consider the case where the task is not completed.

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
owg

Do you quantify the frequency (e.g. with probabilistic figures) of human error independent of error, negligence or gross negligence?

RE: Consideration of Human Error in Risk Assessment

Yes, we apply frequency and severity numbers to consequences. The frequency is more a function of the task rather than of the individual. The frequency is also strongly based on the experience of the team. We would never ask, is this negligence or gross negligence. That would be a sure way to put the team on the defensive. There is a body of literature on the subject which tabulates failure frequencies against various classes of tasks. I could probably find a reference if you need it. I think the nuclear industry developed the methodology.

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
owg

all frequency figures about human error given in data base or literature consider only operator error and do not mention or address negligence or gross negligence.
Therefor we consider in our risk assessment only the frequency figures given for operator error. But up to now there are no data about negligence or gross negligence.
With the consideration of negligence or gross negligence in a risk assessment we have a completely different set of hazards for the offshore windpark (e.g. drunken shipper sails through the windpark) which cannot be quantified.

RE: Consideration of Human Error in Risk Assessment

I'm not sure how you can apply this to your figures.  But on some risk matrix I've seen - credit is NOT TAKEN FOR humans "doing the right thing".  Ie in procedures etc.

On the risk matrix I've used the horzontal grid is probability in bands ie once per year, once per 10 years ..
the vertical grid is severity.  minor injury upto multiple deaths.    On the grid itself is INTollerable, broadly acceptable, alarp measures.  The requirement is to get to broadly acceptable.  

So in general to reduce risk we put in protection measures such as automatic trips, independent systems, which move us down the probability etc.  But again for humands doing the right thing I'm not sure you can take any credit !

There are lots of books on risk assessment which should provide you with references.

Cheers

James


RE: Consideration of Human Error in Risk Assessment

Wolfram - We look upon the frequency data for operator error as covering the complete set of humanity with all its variations. Therefore we consider that the operator failure rates include all the ways and motivations for making the error in question. I suppose in your drunken sailor case, the idea is that the sailor ignores all warning, alarms, etc. because he or she is negligent. It sounds like you need to use a method like Layer of Protection Analysis (LOPA) or a Fault Tree Analysis for the specific scenarios which concern you. LOPA is fairly new. Check out the American Institute of Chemical Engineers, Centre for Chemical Process Safety for a new book on the subject. There are lots of references around for Fault Tree Analysis. I hope this is helpful.

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
LOPA, FTA and all the other tools and techniques are essential elements of our QRA's for offshore installations(see Publications in www.glo-offshore.com). But again if the authority requests to quantify the basic event "drunken sailor" in a fault tree I need credible figures from literature or data base for such a negligence. Do you know a data base or reference with frequency data about negligence or gross negligence? What is the position of Canadian authorities concerning neglegence or gross negligence in QRA?
I tend to share the opinion of james1030bruce to take no credit for undesired events like that.

RE: Consideration of Human Error in Risk Assessment

I think I am correct in saying that neither Canadian nor US authorities require QRA. The reason is that they believe that the quantitative data base is too unrelable for realistic regulation in the chemical industries. In the oil industry we are allowed to assume that an operator will do the right thing in an emergency, given good information on what is to be done, and given 10 to 20 minutes in which to do it.

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

Hi Wolfram,

I would be interested in the detail of the requirements that you say the Germans are placing on the risk assessments. The legal test for negligence is in two parts: firstly does a duty of care exist and secondly has the duty been breached (approximately!)

To link this to human error in a risk assessment is a big step and to my mind the wrong place. Negligence is a decision for the courts. The closest that you will get (I think) is to look at or search for publications on rule violations since, using your example, there would not doubt be a rule that the operators should not drink alcohol while on duty. The UK Health and Safety Executive has published a few publications on human error and human factors e.g.

www.hse.gov.uk/research/otopdf/2000/oto00096.pdf (quite a large file by the way)

N.B. Human error is about more than the man on the ground mis-reading a display there are organisational issues too e.g. training, shift patterns, management support. A good overall view is in "Reducing error and influencing behaviour" by HSE books (HSG48) if you can get hold of a copy.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish

excellent help the publication from HSE. By the way I agree in total with your remarks about human error in risk assessment.
Regards
Wolfram

RE: Consideration of Human Error in Risk Assessment

To the best of my knowledge, Human Error / negligence is never quantified as a risk factor because of the underlying assumption that this is an intolerable situation. However intentional sabotage can be quantified and mitigated.

RE: Consideration of Human Error in Risk Assessment

CEP has published an article on SAFETY, in May 1994, titled Include Human Errors in Process Hazard Analyses by Wm. Bridges et al., page 74+, that may be applicable to this discussion.

RE: Consideration of Human Error in Risk Assessment

(OP)
OlumideAdeoye,
how is possible to quantify (frequency of event or probability figure) intentional sabotage?

25362
is the given reference accessible in the internet? Or do you know how to get it in Germany. Please do not recommend to subscribe the magazin.

RE: Consideration of Human Error in Risk Assessment

to Wolfram, regretfully I was unable to raise the article through the Internet. However, you may, just may, get it free-of-charge from the company that sponsored the article, JBF Associates Inc, nowadays ABS Group Inc. by

http://www.jbfa.com/index.html

And may be they can supply you with more of their works on the subject.

Good luck.

RE: Consideration of Human Error in Risk Assessment

wolfram,

If youy do manage to get that article, could you ask them if they'd mind putting a copy on the net somehow? Sounds useful.

Cheers,
John.

RE: Consideration of Human Error in Risk Assessment

2
We use the following estimate for failure to implement procedure or activity correctly. Ultimately we assume that no risk reduction can be claimed for operator intervention for a complex task required in an emergency situation.

Note Pf = Probability of failure

 1. NO STRESS (EG NORMAL OPERATIONS)    
- SINGLE ACTIVITY  (Pf = 0.0001)
- ROUTINE ACTIVITY  (Pf = 0.001)
- WRITTEN PROCEDURE (Pf = 0.01)
- COMPLEX, NON ROUTINE, CONFILCTING DUTIES(Pf = 0.1)

 2.MODERATE STRESS (EG STARTUP)    
- SINGLE ACTIVITY  (Pf = 0.001)
- ROUTINE ACTIVTY  (Pf = 0.01)
- WRITTEN PROCEDURE (Pf = 0.05)
- COMPLEX, NON ROUTINE, CONFILCTING DUTIES(Pf = 0.3)    

3. HIGH STRESS (EG EMERGENCY RESPONSE)    
- SINGLE ACTIVITY  (Pf = 0.05)
- ROUTINE ACTIVTY  (Pf = 0.3)
- WRITTEN PROCEDURE (Pf = 0.5)
- COMPLEX, NON ROUTINE, CONFILCTING DUTIES(Pf = 1.0)    
        

RE: Consideration of Human Error in Risk Assessment

Wolfram,

OK I won't refer you to a magazine.
Risk Analyses depend a lot on historical data over a defined time window, and this is your best source of information. In rare cases you may project risks based on a scenario that doesn't yet exist. This will require frequent re-evaluation of the risk once historical data becomes available.
Hope this helps.

RE: Consideration of Human Error in Risk Assessment

(OP)
MarkkraM
your probability figures are very similar to the ones we already use in our QRA for offshore windparks. But they are only applicable for "normal" operator error. My problem still remains because German authorities require the quantification of human errors caused by negligence or gross negligence (e.g the drunken shipper). Nevertheless thanks for your figures. It is helpful to know that at least our probability figures for "normal" human error are correct.

RE: Consideration of Human Error in Risk Assessment

(OP)
25362
I asked JBF Associates about the article from Wm. Bridges. They will send me the article but they also informed me that the contents of this article will not be helpful for my problem.

RE: Consideration of Human Error in Risk Assessment

Since you appear to be stuck;I would suggest that you cmoe up with a notional statistic based on soemthing that's fairly well documented with lots of statistics of its own:

http://ai.volpe.dot.gov/CrashProfile/CrashProfileMainNe...

Truck operations are one of the most stressing and full-time operator dependent functions.  Given the available statistics, you should be able to synthesize a hypothetical number for operator related incidents, particularly since a substantial number of truck accidents are operator error or failure related.

TTFN

RE: Consideration of Human Error in Risk Assessment

(OP)
IRstuff
could be difficult to apply human error data of truckers to the management of ships or operators of vessel traffic control centres. But the figures given in the US crash profile are better than nothing and a first approach to get a feeling about the share of negligence  and gross negligence in human error statistics. Thank you I will present it at the expert panel and may be later at court.


25362, JOM
I received the article about "Human Error in PHA" from Mr. Farquharson of ABS Consulting. If you are interested to get this article please contact me (wbr@gl-group.com).

RE: Consideration of Human Error in Risk Assessment

wolfram,

I wonder if the IMO (International Maritime Authority) has anything to offer on this? They have been investigating maritime disasters for decades. How about the US National Transport Safety Board?

The Australina Transport Safety Bureau has a large collection of shipping accident reports. I can think of two off the top of my head that might be in the category you are after.

A ship ran aground while the captain was talking to his spouse - he failed to make a turn.

Another ship ran aground while the captain was asleep in his cabin with a blood alcohol level of 0.29 g/100ml.

How do you turn that into a statistic?

Cheers,
John.

RE: Consideration of Human Error in Risk Assessment

(OP)
John
ATSB has an excellent website about the investigation of shipping accidents and some of them reveal negligent or gross negligent actions of the ship management(as mentioned in your response). But I could not find statistics on their website in which they indicate the share of negligent or gross negligent actions causal for the accident. IMO has no statistics about this and I guess as long as black boxes are not mandatory for all ships we will never get reliable data about this issue.

RE: Consideration of Human Error in Risk Assessment

I just remembered the CCPS book, "Guidelines for Chemical Transportation Risk Analysis". They have some failure data on Barges and Ocean Going Vessels. An example is a Table on Primary Cause of Marine Incidents. They have an Incident Type "Fault of Personnel/other vessel" and show 69% of the incidents attributed to this cause. Poor weather shows only 3%. Let me know if this type of data is helpful.

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
owg
it is well known in marine industry that the primary cause for marine accidents is human error. International literature and data base allocate 60 - 80 % to this type of failure.
Still the question remains, how is human error handled in QRA within chemical and petrochemical industry and is negligence or gross negligence part of the qualitative or quantitative risk analysis?

RE: Consideration of Human Error in Risk Assessment

Techniques like HEART (Human Error Assessment and Reduction Techique) and THERP (Technique for Human Error Rate Prediction) will give you values for human error that you can feed into a fault tree analysis but I think that you still need to think about violations rather than negligence.

A violation may be defined as "a deliberate deviation from the rules, procedures, instructions and regulations drawn up for the safe operation and maintenance of plant or equipment" (from HFRG1995 'Improving Compliance with safety procedures - reducing industrial violations' by Human Factors Reliability Group, HSE Books)

This excludes acts of sabotage, mischief and vandalism. The current approach in UK safety cases (which include QRA/PSA sections) is to present a deterministic arguement that the prevailing safety culture is adequate to prevent such deliberate actions. The arguements would be based on demonstrations that arrangements for selection, training, supervision and discipline of personnel are adequate and that the work environment and operating procedures are such that violations are not encouraged.

Recent work for the UK Health and Safety Executive, on conventional hazardous industries, doesn't really add much on violations e.g. http://www.hse.gov.uk/research/rrpdf/rr081.pdf

Williams has modified HEART to include nominal violation probabilities which are then modified by application of violation producing conditions (VPC). I think that this work was done in a PhD thesis but whether you can get hold of a copy I do not know. Williams, J.C. (1996) Assessing the Likelihood of Violation Behaviour. University of Manchester. Department of Psychology.

Hope that this helps. Do you have a copy of the text of the requirements that the German authorities are placing on the risk assessments. I would be interested to read more.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

MarkkraM,

The figures you quoted - can you tell us their basis, please? Where do they come from? How widely are they accepted?

I'm not questioning them, just curious to know how they came about.

You say that the probability of error when following a written procedure under moderate stress if 0.05. Now, obviously you don't actually KNOW that, so is it a case of "until someone comes up with a better number, I'll use this one"?

I'm not being critical, just want to learn. That number says that when following a written procedure during an episode of moderate stress, personnel will make an error one times out of twenty episodes. That's pretty significant, don't you think?

Cheers,
John.

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish

O.K. let's talk about violations instead of negligence. Your statements how this issue is handled in a UK safety case are very helpful for me. Also I will try to get the briefing notes of IP and the thesis of Williams for further evaluation.
The requirements of the German authorities are stated in the minutes of meeting for a running offshore windpark project. There are no legal requirements about that in Germany.

RE: Consideration of Human Error in Risk Assessment

Sorry Wolfram, easy to get fixated on one aspect of a problem. I'll try to think top down for a bit!

Human factors according to HS(G)48 is a combination of

Job factors: what are people being asked to do and where (the task and its characteristics)
Individual Factors: who is doing it (the individual and their competency)
Organisational Factors: where are they working (the organisation and its attributes

In addition to these points human error could be classified as errors of

1)Omission: either omitting a step in a task or omitting the entire task

2)Commission: including selection errors, sequencing errors, timing errors or performing actions but to the wrong degree (too quickly or too slowly)

3)Violations: action (or lack of action) which is deliberate but non-malevolant


The type of task is significant too, is it purely skill based where there is little or no mental processing by the operator, rule based where the operator perceives something and acts according to external prompts or is it knowledge based  where the operator must perceive, interpret and act according to his experience and training.


The dictionary says negligence is "a failure to exercise the degree of care considered reasonable under the circumstances resulting in unintended injury to another party". I suppose that this could happen via a variety of paths so we should consider looking at how the different human errors could be included in charges of negligence.

a) Skill based errors can happen because of environmental factors like noise, poor lighting or poor interfaces affecting operator perception or poor labelling, interfaces, supervision or PPE affecting the operator response to the perception.

b) Rule based errors can occur where there is poor training, expectations, cultural factors or poor procedures.

c) Knowledge based errors can occure because of knowledge, personality, culture or time.

Violations are subject to similar structure:
d) routine violations tend to be at the skill based level and tend to be time saving, energy saving and there is usually a lack of enforcement typically endorsed by comments like 'we all do it this way', 'nobody said we shouldnt' etc

e)situational violations occur at rule based level and tend to occur because there are features that prevent or inhibit correct performance. e.g. 'the gauge cannot be read at the same time as turning the switch' 'we cannot hear radio messages with our ear defenders on'

f)exceptional violations occur when there is time or psychological pressure or a potential crisis and the only solution that can be thought of requires rules to be broken e.g. 'i cant stop the pressure rising so will have to manually vent' or 'we must reach targets so lets keep pumping while we can'

As you can see negligence could occur at a variety of levels (organisational or individual) and situations and the only way that it will truly be decided is hindsight after something bad has happened.

A fair approach to integrating human factors into a risk assessment is as follows:
1) Identify safety critical tasks e.g. tasks associated with critical equipment, system functions or hazardous materials. Ideally criteria for identifying these should be established to safety assessements to ensure consistency and that management is aware of risk levels. This is an important step because human factors and task analysis can be expensive.

2) Assess the quality of task support, is the task dependent on lots of human input or have numeric risk targets been set.

3) Identify and assess the consequences of specific human errors including failure to complete tasks on time.

4) Model human errors alongside equipment failures. This would need methods like HEART or THERP etc

5)Risk Assessment including screening quantifying and comparison with risk targets

6)Risk Reduction could be achieved by improving the task or by improving the supporting infrastructure


To avoid a charge of negligence the Company would have to demonstrate that the operators were trained, adequately supported by the design of the task and the equipment. To avoid a charge of negligence the operator would have to show that they did as they were trained, followed procedure or that they understood the plant sufficiently well to make knowledge based decisions about its operation and that the decisions they made were consistent with that understanding. Usually in an accident there are multiple causes some operator based and some organisational based.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish
your remarks are superb and I will follow your recommendations as much as possible. But how to apply HEART or THERP for all the ships (ships with individual bridge design, equipment standard, crew standard etc) passing the offshore windpark and how to get reliable data (probability or frequency figures) about routine, situational and exceptional violations?

RE: Consideration of Human Error in Risk Assessment

Hi Wolfram,

Oops again, nothing wrong with what I said but just finally realised what it is that you are after. Just to be clear could you confirm?

You are involved in the design of the offshore installation and are trying to assess the risk of impact from another vessel over which you have no control.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish
I assess the risk of an offshore windfarm (German Bight, area approx. 200 square kilometer, 214 wind turbines, each wind turbine is approx. 120 m high and the diameter of the pylon is approx. 10-15 m) which is more or less close to a lot of shipping lanes (approx 35000 passing ships per year). There is also a vessel traffic control or monitoring centre inside the windfarm. Now the question arises what happens if a skipper or operator of the control station makes a mistake (human error).
No problem for me to do this in a qualitative manner (FMECA and qualitative fault tree). Little bit tricky but manageable to do it quantitatively for "normal" operator error by using similar huma error rates mentioned in the statement of MarkkraM (see above). But how to do it (qualitatively and quantitatively as requested by German authorities) for the drunken skipper or sleepy operator and all the other acts of negligence or gross negligence?  

RE: Consideration of Human Error in Risk Assessment

Wolfram,

Just out of curiosity - are these turbined manned?

Does Germany apply the COMAH rules to its hazardous industries? Do COMAH rules refer to gross negligence (what shall we do with a drunken sailor?)?

What I'm getting at is you may find the answer in your own backyard. Does Germany have any offshore drilling rigs? If so, how do they deal with it? What about Netherlands, Denmark or the UK?

Your industry is windfarms. Is it fair for the authority to ask you to assess the occurrence of human error in an industry you are not part of - shipping?

With the very large volume of ship movements in your area, surely someone has figures for ships going where they are not supposed to - reefs, beaches, sand banks, oil rigs. Does the cause really matter? I think the others have said the same thing ("it's all violations") and you say the authority requires the "drunken skipper" figures.

I think we're all interested in how you solve this one!

All the best.


Cheers,
John.

RE: Consideration of Human Error in Risk Assessment

I agree with JOM the events that you  are trying to prevent are from external initiators, there is not much you can do in your design which will actually stop people colliding with your windfarm although the fact that it's 200km across would be a wake-up call. Surely it would be marked on shipping charts like oil-rigs or lighthouses etc.

The key thing to think about is what do the authorities want to achieve by carrying out the risk assessment: is it an estimate of the frequency of collision to use to assess whether they need to include a ship impact barrier to prevent power outages affecting downstream users? Are they concerned about loss of life? The design of the windfarm will no doubt have a certain impact resistance which may be higher than most of the traffic without radar (or it may not, you would need a graph of frequency of collision against vessel size to work that one out).

I started thinking of how the solution might be 'engineered out' with something similar to the Traffic Collision Avoidance Systems (TCAS) that are now fitted to aircraft and came across the following for assessment of ATC interfaces
http://citeseer.nj.nec.com/leadbetter00formal.html

and www.nilim.go.jp/english/report/annual/012.pdf for similar work going on in maritime industry.

Of course the problem with giving operators an engineered system is that they may tend to rely on it leading to disasters like the 1995 grounding of the Royal Majesty passenger vessel!

See also http://www.hse.gov.uk/research/otohtm/2001/oto01053.htm for issues surrounding human error dependency on engineered systems.

Still mulling this one over!

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

(OP)
JOM

it is planned that for each offshore windpark the owner has to provide a permanently manned vessel traffic control and monitoring centre which is equipped with radar, AIS and VHF/UHF radio. The control centre will also be able to control and monitor remotely each turbine of the windpark.

In Germany we have rules and guidelines which are the same as COMAH because in Europe we have the Seveso II directive for hazardous plants and installations and each EC member has to adhere.

My investigations in Norway, UK and the Netherlands revealed that negligence or gross negligence was never tackled in a safety case or risk assessment about offshore installations.
In Germany the same situation for onshore plants and offshore installations but now German authorities require the consideration of negligence + gross negligence. They do not ask how other nations handle this problem in a risk assessment and it is strongly recommendable not to mention the term "fairness". They argue it was forgotten or omitted in the past and now they want to do it better.

Hamish

It is common standard in marine risk assessments (offshore drilling platforms or offshore windparks) to assess the whole system including environment. That means if there is an offshore installation or windfarm you have to evaluate among others the risk of collision. Please have a look at www.glo-offshore.com. Under "News/Publicat." you may find an article about "Risk Assessments for Offshore Installations" which describes our approach.

The authorities and environmental pressure groups fear the risk of environmental pollution. If a tanker or any other ship collides with such a turbine there will be a leakage in the cargo oil or bunker oil tank. Because of the high number of turbines and passing ships they argue a catastrophic oil pollution is unavoidable within short time.

Well now after delivery of our risk assessment the authorities and environmental pressure groups accuse us to be too optimistic with our calculated collision frequency and collision risk. They argue -and it is correct- we have not considered sufficiently negligence or gross negligence of the people involved (e.g. the drunken skipper or sleeping operator of the control centre).
In our probabilistic model (fault tree and Monte Carlo Simulation) we have considered all technical failures (e.g. engine failure, radar failure) and of course human error. But the human error data we used are not applicable for negligence or gross negligence. They are only applicable for "normal" human error (e.g. misinterpretation of radar signals, wrong course, wrong radio channel). We could not find any reliable data about negligence or gross negligence.

So I am still looking for reliable data about negligence or gross negligence to satisfy our authorities and if necessary to correct our risk assessment. I am also very keen to find official statements (nevermind which nation)in which the exclusion of negligence or gross negligence in a risk assessment is clearly stated.

 

RE: Consideration of Human Error in Risk Assessment

One aspect of this discussion bothers me. A distinction has been made between "normal operator error" and negligence. Failure data has been presented for various tasks. I have used this data before and I do not remember any footnotes to the effect that negligent behaviour is excluded from the data. I therefore have assumed that the data applied to the full range of operators including the tired, the drunk, and the drugged. Why are we assuming that they are excluded from our data base?

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
owg

if you reed the first publications about human error reliability or human error analysis (e.g. NUREG handbook about Human Error Analysis or the publications from Hunns and Daniels) you may find the indication that all human error rates were collected and analysed by the participation of hundreds of test subjects and thousands of operator actions. In no publication you will find a remark that the test subjects were drunk or high. Instead you will find a lot of remarks about the composition of test groups and test subjects (e.g. age, sex, education and physical condition). Again nothing was mentioned about drunken test subjects.

I think you make a big mistake in your risk analysis if you include acts of negligence and gross negligence to the given or published human error rates.

RE: Consideration of Human Error in Risk Assessment

Wolfram.

I think we've now got a better appreciation of your situation. It's not so much a question of protecting the turbines, but protecting shipping and the environment.

Is there some contradiction in the argument against the windfarm because of the possibility of oil pollution? The windfarm produces clean, green power? There should be some positive arguments in favour of the farm.

Recently I heard of a scheme from a DVD manufacturer or perhaps a video store chain. They propose producing DVDs that self destruct when the hirer starts using the item.

This means that after a number of days the DVD becomes unplayable. So the hirer throws it away. At present they have to return their rented DVDs to the store.

This scheme would generate a new waste stream of plastic discs and containers. The company argues that because customers do not have to return the DVDs to the store, there is a reduction in vehicle journeys. Reduced fuel consuption. Reduced greenhouse gases. so overall, their would be a nett benefit to the environment.

Clever argument.

Will the windfarm generate power that would otherwise be produced by oil fired stations using imported oil? Would that result in lower oil imports and fewer tanker movements?

That would mean reduced numbers of tanker incidents and oil spillage. So the windfarm might generate a nett gain for the environment.

Cheers,
John.

RE: Consideration of Human Error in Risk Assessment

Hi Wolfram, found the enclosed which might give you either contacts or references of use.

http://www.cs.auc.dk/~pba/Preprints/HumError could be of use as a method to compile empirical data for probability of accidents caused by drugs/alcohol.

The contents of the thesis shown at
http://www.geocities.com/tsgreg2002/abstract.htm
lists chapter 4 as looking at the role of alcohol and drugs in shipping accidents. Couldn't see anything more than the contents but you could try mailing the author.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

Wolfram,

JOM said "Is it fair for the authority to ask you to assess the occurrence of human error in an industry you are not part of - shipping?

With the very large volume of ship movements in your area, surely someone has figures for ships going where they are not supposed to - reefs, beaches, sand banks, oil rigs. Does the cause really matter?"

Perhaps looking for the contribution from negligence is a red herring since 'other' human error will play a part too. You could take a look at historical data / accident reports and say x% of the accidents were judged to have a root cause of negligence (never that simple) and then put another or-gate into your fault tree. The problem is whether you could review enough data to build up a picture worth using.

I think that to substantiate that you could contact the operators of the types of ships capable of causing catasrophic or major environmental incidents and ask them how they encourage people NOT to drink etc, what kind of shift system they operate and what the manning levels are for ships of those types. That way you can get a feel for the safety culture of the shipping.

I think that the requirements to ASSESS the risk would have to be done but by the OPERATOR of the ships. Either yourselves or the German government need to request/contract them to do this for you. Surely there must be a requirement on the operator to have produced risk assessments for their work?

I read the paper on the link you provided and was wondering if there were any better criteria to use for harm to the environment than small, serious, big and severe. Has anyone used numerical criteria to assist you in targeting the types of operators to ask the above question? If it were categorised in say number of barrels of oil released or number of birds killed then you could start to think about whether that size of ship COULD be damaged by the impact.

Then you paint a picture of defence in depth: The wind farm is as far away from the shipping lane as we can make it, it will be marked on charts, there are engineered collission avoidance systems being developed, there are two operators on duty to support each other, the safety culture of the shipping operators typically supports the skippers to be alert etc and even if there is a collision the type of ships capable of causing environmental damage is not harmed by the (glancing?) impact with one of our wind turbines.

I think after that you have to start making ALARP arguements since the public at large will receive a benefit from the power the windfarm will provide. Surely that is in the national interest.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish

all the time fascinating how you get the references.
The publication from Mr. Koester (Danish Maritime Institute) is an excellent publication about categorization of human error in marine industry. Furthermore it describes quite plain the problems of understanding and analysing human errors. In fact it is one of the best publications about this topic within the last five years.

The second reference is nothing news. More or less it is the same as already published by Prof. Soares  (University of Lisboa) about human errors in marine industry.


JOM

your statements about net gain for the environment are correct but it does not solve the problem.


The problem :
 1.How is human error considered in qualitative and quantitative risk assessments?  
 2. How are acts of negligence or gross negligence (e.g. the drunken skipper or sleeping operator) considered in qualitative and quantitative risk assessment?

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish

if you are dealing with risk assessments for offshore installations it is worldwide common practice to consider the shipping traffic around the offshore installation (please look at www.standard.no/standard/NORSOK_standards/2169/Z-013.pd... which is one of the best standards for marine risk assessments).
You cannot shift the problem to shipping companies or national authorities. And if you read the excellent article of Mr. Koester you may see which difficulties occur if you try to analyse accidents reports about marine accidents. It is frustrating and currently not the method to derive human error data which gives you a flavour about negligence and gross negligence.

So who can show me an official statement how acts of negligence or gross negligence are handled in qualitative and quantitative risk risk assessment.

RE: Consideration of Human Error in Risk Assessment

Hi Wolfram,

I found the following link on the UK Maritime and Coastguard Agency site

http://www.mcga.gov.uk/c4mca/mcga-regs/windfarm

which is the steps taken to address navigational safety in teh consent regime for establishment of wind farms off the UK coast.

I am still reviewing the NORSOK standard.

I agree with you that you have to take account of the impact that YOUR structure will have on surrounding area and traffic, however you seem to be implying that it will be your responsibility to carry out human factors assessments of how likely it is that drunken skippers will crash into your structure i.e. activities that you have no control over. You might as well include the risks that the drunken skipper will crash anyway, but I do not see the point.

The assessment of tasks that you cannot control does not make sense; the whole point of risk assessment is that if you evaluate the risk and it is too high when compared against the relevant criteria then you take steps to reduce the risk. If you have no control over the risk then this last point is not possible.

You can assess the actions of the control room operators of your windfarm failing to interact properly with the surrounding shipping (and maybe even how likely it is that they will be drunk) but this would fall under the advice given previously by myself and others.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish

thank you for the given reference of UK MCGA but the requirements/recommendations of this authority are very similar to the one already published by the Dutch and German authorities.

I have never said that it is my responsibility or task to perform a HF assessment for all ships passing the offshore windfarm. But I have been asked by national authorities and environmental presuure groups to consider acts of negligence and gross negligence for the QRA.

If you are not able to perform an individual or ship specific HF assessment to solve this problem you are allowed to use generic human error rates (published by NUREG, Hunns and Daniels, Swain and Gutman and many others)like the ones listed by MarkraM (see above).

In the frault tree model and Monte-Carlo-Simulation we included several times the basic event human error (e.g. misinterpretation of radar signals, wrong course of the ship, switching wrong UHF channel etc.). For all the basic events we allocated generic human error rates and together with the technical basic events and failure rates we got a nice result about collision frequency and collision risk.

Now authorities and environmental pressure groups argue the risk assessment is wrong because acts of negligence or gross negligence are neither qualitatively nor quantitatively considerd.
Unfortunately the published generic human error rates are not applicable for acts of negligence and gross negligence. Furthermore the  qualitative part of the risk assessment the so called HAZAN was done without consideration of negligent & gross negligent acts like switching off the dead man alarm, switching off the collision avoidance alarm, looking TV during watch etc.. All these acts are reallity in marine industry and it is difficult to defend a QRA without it.
So the solution could be to include qualitatively all these acts of negligence and gross negligence into the risk assessment (by the way who has experience in doing this and is it reasonable to do it?)and to define technical and organisational measures of protection.
But how to do it quantitatively? I don't know. Now we put in the fault tree model the basic event "acts of negligence & gross negligence" directly below the top event "Collision" but without allocation of probabilities (only as qualitative event).

How do you handle this problem (negligence & gross negligence) in nuclear industry?

Regards
Wolfram

RE: Consideration of Human Error in Risk Assessment

Hello Wolfram.

I believe the 2005 World Wind Energy Conference is to be in Melbourne, Australia - my home town.

Your problem sounds like a good paper to present to the next conference.

Cheers,
John.

RE: Consideration of Human Error in Risk Assessment

(OP)
curryhydrocarbons

I am not sure whether your tip with a more or less vague statement about the list of reference is a help or a burden.

RE: Consideration of Human Error in Risk Assessment

Wolfram,

I think from the previous posts that you are unlikely to get a definitive answer to your question in one place, more than likely you will have to piece it together from various references. To rebuff someone who is offering a tip or pointer to where you may find the strategy seems a little rude.

I think that if you consider a deterministic arguement based on the numbers of actual accidents in the area that you plan to site the windfarm then that will give you the bounding case. If I were you I would give a ROBUST reply to your regulators / crtitics telling them that they are asking for too much detail from someone who is not the duty holder (i.e capable of reducing the risk) and ask them what criteria they would like you to use. In the nuclear industry the usual way of treating external events is to generate statistics from historical records.

From my previous posts it should be clear that some negligence could be from 'normal' human error and some from violations BUT that the charge of negligence would be made by the courts, after the considering all the evidence to establish whether the operator or the organisation (or both) were negligent.

Regards, HM.

No more things should be presumed to exist than are absolutely necessary - William of Occam

RE: Consideration of Human Error in Risk Assessment

HamisMcTavish - Thanks, I needed that.

HAZOP at www.curryhydrocarbons.ca

RE: Consideration of Human Error in Risk Assessment

(OP)
Hamish

Hamish you are right my remark about owg's pointer was uncalled and I am sorry about that.

I agree with you that it is time now to come to an end.
Looking back to all the tips I have received during the last days I say thank you very much to all the one's who tried to help me. Nearly all tips were helpful and it is my task for the next days to put the bits and peaces together.

I will try the ROBUST reply and also use your arguments. We will see how this matter will end. Everybody who is interested about the progress of this issue may contact me under wbr@gl-group.com at January next year.

Cheerio
Wolfram

RE: Consideration of Human Error in Risk Assessment

wolfram ,
I started to read the long thread just out of curiosity , but spent a lot of time to read it all , because your problem isn't easily solved.

I can't give you any concrete help on this matter , not being into this specific sector , nor doing Hazop's.

However , I think you also could look into another direction to collect further intelligence : my country (belgium) decided some time ago to implant 65 x 2.5MW windturbines in an offshore park just on the outlet of the English Channel , turbines supplied by a renowned danish windpower manufacturer , that also posted intel on this on his website (a competitor of your company ?).  Given the location of this 65 turbines implantation amid one of the biggest marine traffic locations in the world ( ships going to Antwerp , Rotterdam , Hamburg and Bremen ) , they surely would have to also complete some analysis similar to your problem.  The turbine park will be implanted om an offshore sand bank , that surely already is put on marine maps , but I suppose this information will help you find another channel of information to try to solve your problem.

Interested to see how this will pan out . . .

RE: Consideration of Human Error in Risk Assessment

(OP)
azertyuiop

we already delivered a QRA for a Belgium offshore windpark project. The Belgium authorities are very pragmatic and professional. There is no problem with the consideration of human errors in risk assessment.

Regards
Wolfram

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