04-08-2009, 04:26 PM
Mark
Hoping to make a helpful contribution rather to leave you feeling that I am jsut being picky I have lksited your hazrds below with comemtns that may illumninte the points that PJW has made.
Most importnatly it is absolutley key to define "the system" as the hazards will lie on the boundary of that system - whatever it is - I have taken your definition of work as the basis.
Head on/ rear collision during single line working - this is an accident i.e one example of the possible harm that can arise from the hazards inherent in the system / process we are studying. It is probably the most harmful outcome but not I woudl suggest the most likely. We use the concept of risk to help us "measure" its importance.
Fire in Tunnel after collision with derailed train - another outcome (though fire is an awkward customer that doesnt fit the EN / YB model very well). Certainly it is outsdie the control of your process so it is not a hazard - it may be best to deal with it in the casualty modelling.
Difficulty of egress in an emergency - this is going to effect the severity of the outcome (the amount of harm) and probably cannot be influenced by your process so it is not a hazard.
Lack of access for emergency services - as the previous one, though you shoudl be taking this into account b the mitigation measures you design into your process/system. The harder it is the more reasonable it will be to spend some moeny and effort in makign it easier.
Emergency exit route blocked in both directions by train wreckage - this again influences the outcoem, in this case for worse.
Confusion who is in-charge of single line working - this now soudns liek a cause (or causal factor) as it is within your control to get this right. if it is wriong then you amy be lucky and get away with it otherwise there will be some degree of escaltation.
Rest assured that this is not easy adn EVERYONE gets it wrong and there are often endles debates about waht is a cause/hazard/consequence. however it is achievign this clarity early on which is at the root of designing a safe enough system or process. This avoids the courtroom debate about I thought you meant...or I didnt realsie that was included...etc. This kind of thigns is called fault and event free modellign in YB - the faults or causes (because you can have hazards even when everything is working proprerly) lead to hazards the consequences of whcih can be modelled in an event tree. This is not the only way to model - outside the UK people and in other industires peopel use Bowtie diagrams with a rather more visual and very good at modeling the barriers pr mitigations.
As to what really are the hazards in your process / project I would suggest things like:
- erroneous but valid movement authority given to train
- deliberate disreagrd of movement authority
- distraction (may be a cause....)
- train fails or separates in section without notification
These are rather general and woudl need a bit more flesh on them for the exam. Your consequnece column looks OK but remember there is always the nothing happened today outcome (usually the most frequent). Hope this helps
Hoping to make a helpful contribution rather to leave you feeling that I am jsut being picky I have lksited your hazrds below with comemtns that may illumninte the points that PJW has made.
Most importnatly it is absolutley key to define "the system" as the hazards will lie on the boundary of that system - whatever it is - I have taken your definition of work as the basis.
Head on/ rear collision during single line working - this is an accident i.e one example of the possible harm that can arise from the hazards inherent in the system / process we are studying. It is probably the most harmful outcome but not I woudl suggest the most likely. We use the concept of risk to help us "measure" its importance.
Fire in Tunnel after collision with derailed train - another outcome (though fire is an awkward customer that doesnt fit the EN / YB model very well). Certainly it is outsdie the control of your process so it is not a hazard - it may be best to deal with it in the casualty modelling.
Difficulty of egress in an emergency - this is going to effect the severity of the outcome (the amount of harm) and probably cannot be influenced by your process so it is not a hazard.
Lack of access for emergency services - as the previous one, though you shoudl be taking this into account b the mitigation measures you design into your process/system. The harder it is the more reasonable it will be to spend some moeny and effort in makign it easier.
Emergency exit route blocked in both directions by train wreckage - this again influences the outcoem, in this case for worse.
Confusion who is in-charge of single line working - this now soudns liek a cause (or causal factor) as it is within your control to get this right. if it is wriong then you amy be lucky and get away with it otherwise there will be some degree of escaltation.
Rest assured that this is not easy adn EVERYONE gets it wrong and there are often endles debates about waht is a cause/hazard/consequence. however it is achievign this clarity early on which is at the root of designing a safe enough system or process. This avoids the courtroom debate about I thought you meant...or I didnt realsie that was included...etc. This kind of thigns is called fault and event free modellign in YB - the faults or causes (because you can have hazards even when everything is working proprerly) lead to hazards the consequences of whcih can be modelled in an event tree. This is not the only way to model - outside the UK people and in other industires peopel use Bowtie diagrams with a rather more visual and very good at modeling the barriers pr mitigations.
As to what really are the hazards in your process / project I would suggest things like:
- erroneous but valid movement authority given to train
- deliberate disreagrd of movement authority
- distraction (may be a cause....)
- train fails or separates in section without notification
These are rather general and woudl need a bit more flesh on them for the exam. Your consequnece column looks OK but remember there is always the nothing happened today outcome (usually the most frequent). Hope this helps