- Explain the concepts of risk as a social construct, risk perception, risk communication, risk acceptability and risk
- Apply a variety of risk treatment techniques including: mitigation, avoiding, transferring, sharing and
- Apply risk tolerability in the context of
- Apply the concept of the hierarchy of risk
- Quantify risks using a variety of risk assessment
- Work professionally, collaboratively and productively in a team
1. Identify and describe in detail four engineering failures chosen from following categories (maximum one failure per category):
- Large and localised (e.g. Granville train accident 1977).
- Medium and localised (e.g. Thredbo landslide 1997, deaths during the construction of the Sydney Harbour bridge 1922-1932, Childers backpackers hostel fire 2000, Sydney Bowlers Club fire 1994, Dreamworld accident 2016).
- Small and localised (e.g. Hoyts theatre retractable seat accident 1997, Soccer goal post collapse 2003, Lend Lease/UTS crane fire 2012).
- Large and widespread (e.g. Esso Longford gas explosion 1998, CSR-James Hardie asbestos contamination of both commercial and domestic premises Australia 1948-2013).
- Medium and widespread (e.g. magnets in children’s toys 2010, blinds, curtains and window fitting childhood strangulations 2010, Orica soil contamination 1990-2013, Mt Isa lead levels in children 2007-2013, Queensland CSG contamination 2013).
- Small and widespread (e.g. Sydney water cryptosporidium and giardia contamination 1998; bunk beds childhood falls 2005; Backyard trampoline non-compliance 2003-2013).
2. Whatever failure you choose, it must be an engineering failure for which you can readily obtain information. You are required to provide a brief background to the failure and why you believe your example qualifies as an engineering failure (as distinct from a non-engineering failure). You may choose each individual failure from different engineering disciplines.
3. Place yourself in the seat of an engineer who was causally involved in each failure and answer the following questions for each failure:
- How would you have done things differently?
- What should have been the barriers that prevented the failure occurring?
- What lessons were learnt from this failure?
- What were changes and/or improvements to Law, Codes, Standards, work practices and technology that flowed from this failure?
4. For each failure:
- Define the Inherent
- Describe in detail the causal chain (i.e. show causality from the root cause(s) to the failure event) and provide a causal diagram for each failure .
- Conduct a risk assessment to quantitatively verify the magnitude of the risk exposure in terms of deaths/injuries/damages/costs using a recognised
- Would the pre-failure mitigation have passed the HSE Tolerability of Risk (ToR) test (i.e. you need to demonstrate the consequences of the failure in terms of deaths/injuries/damages/costs to confirm whether they were/weren’t 10x or greater than the sacrifice/investment entailed with the implementation of any pre-accident countermeasures).
5. The report must include a variety of material that supports the discussion and all content must be fully referenced.
6. Marks will be awarded for reports that demonstrate a high level of professionalism and well thought- out technical content
7. Marks will also be awarded for reports that show logical and robust methodological argument that supports the discussion
8. Marks will be deducted for reports that are unfocused and do not effectively address the allocated topic or provide added value discussion
9. You should use the IEEE template provided on UTSOnline
Engineers have an important role in society. They are responsible for designing, building or creating something based on a specification or guideline to meet a particular need. What they develop must function without failure, for its intended lifetime. Engineers are responsible for ensuring that the product of their work meets its intended purpose and level of performance, and avoiding failure, especially a catastrophic failure that can result in damage to property, environment, and even loss of life. Engineering is about managing risks. It is technically impossible to remove risk altogether and lowering risk commonly involves a substantial cost. Engineering as a profession progresses through both its successes and its failures. As a profession we need to learn from failures. Many of the examples used in this subject were disasters. One might be led to conclude that this subject is all about avoidance of large-scale failures. This is not the case: whenever a well-known failure was used as an example, its use is a matter of convenience. The assumption is that the failure doesn’t need to be described in detail for you to understand the principles involved. By analysing failures engineers can learn what not to do, and how to reduce the chance of failure. This may seem paradoxical but is widely accepted. Failure often can spur on innovation. In engineering it is important to review failures, and mistakes. It is harder to learn from success, but you should always learn from failure. This is not the best practice in some engineering projects where failure results in human and property damage, however when a failure does occur it is very important to analyze it and learn from it.
Failures have elements in common. The lessons that we learn from them can help engineers predict and avoid failures. A skill that all professional engineers need is the ability to predict and avoid failures no matter what their scale or magnitude from small or localised to large or widespread. Factors such as human error, decisions to reduce project duration or cost and failure to comply with existing Laws, Regulations, Codes and Standards have historically led to failures. Engineering Failures are typically the result of:
- Human factors – both ethical and accidental failure;
- Design flaws – typically a result of unprofessional or unethical behaviour;
- Materials failure; and
The report will consider any unethical practices that may have led to engineering failure. Engineering failures can be categorised based on the size of the impacted region, and the level of impact on the region. Size of impact:
- Localised: This type of failure will only have an impact on the immediate area where the incident occurs; and
- Widespread: Although the causing incident was localised it has effects distributed over a large geographical
Level of impact:
- Small: Minor Injuries and property damage, may not result in loss of life;
- Medium: Some loss of life, multiple serious injuries, or serious property damage; and
- Large: Catastrophic failure, with extensive loss of life, and severe irreparable property damage.
The United Kingdom Health and Safety Executive (HSE) espoused a framework otherwise known as tolerability of risk (TOR). TOR is used for worst-case considerations, utility-based conditions that entail the societal unacceptability of risky situations, and technology-based cases that tend to ignore the tradeoffs between benefits and costs. The HSE includes principles that require risks to be reduced to as low as reasonably practical (ALARP). This allows the cost of reducing risks to be considered when determining whether to invest in a risk reducing activity. In general, project owners are required to invest proportionately higher levels of funds towards reducing higher risks, particularly for a risk with severe consequences.
It is expected that each of the six failures should be analysed to determine the costs that should have been invested in the project to prevent the failure, and the cost of the consequences of the failure with regards to death, injuries, damages and cost. For each of these failures, the costs that were incurred after the project failure shall be calculated. What it would have cost to put measures in place to avoid the failure shall also be calculated. The multiplier or ratio is used as a measure to confirm whether society should have invested more funds to prevent this failure1. The results should be consolidated into a summary table.
By analysing past failures, engineers can prevent future failures, both minor and catastrophic. It is often the catastrophic failure that receives professional and public attention, but as you will discover, catastrophic failures are comprised of multiple smaller errors in design, communication and/or judgement. Engineering is a constantly evolving discipline due to both advances in technology and the integration of lessons learnt through failures into laws, standards, work practices and technology.
Despite the wide variety in the size and impact of the failures in this Assessment Task, many of the lessons applicable to improving risk management are the same. First, all projects should include a risk management process and a thorough assessment of the risks. In each of the case studies, risks that contributed to the catastrophic failure could have been identified and mitigated through a risk management process. Second, independent reviews of design drawings and specifications greatly increase the chance of detecting human errors and failures to comply with existing codes, laws and regulation.
Human error will never be abolished, but safeguards can help mitigate the impact. Third, time, cost, quality and scope constraints can have significant negative impacts on the outcome of the project or product. While all projects operate within these constraints, the impacts of these constraints need to be part of the risk assessment.
Engineering failures are very subjective due to the perception and amplification of risks by society. Engineering failures are thought of more critically as there usually is no control over the incident from the people involved. One example is airplane travel: more people die on the roads annually, than by flying. However as there is no control over the plane by the passengers it is regarded as a much more serious failure.
Engineering failures typically involve a sequence of events that lead to the failure. There are documented failures that contained complex and/or multiple causal events such that if even a single causal event were prevented or removed the incident would not have occurred. The sequence of events is typically preventable by removing a single element from the sequence.
The cost of these fixes is often very small compared to the overall cost after the failure has occurred. Some risks are out of the control of engineers, and these must be managed in other ways. Although they all involve physical component failure or malfunction the cause of failures is commonly due to human interaction, either by cutting costs, pushing availability or having improper communication channels.
In the tear 1998, approximately 85% of water in Sydney was processed through the Prospect water filtration plant. It is among the largest of its kind, with the capacity to process 3000 megalitres of water in a day, located on a Greenfields site in Sydney’s west and has the ability to supply water to over three million people (Stein, 2008, pg 426). The prospect plan draws its water through a long pipeline from the Warragamba catchment located near the Blue Mountains. Water in the prospect is the filtered, disinfected and fluoridated to remove any harmful contaminants. There are different processes involved such as chlorine was used to kill viruses and bacteria while filtration was used to remove chlorine-resistant parasites and other matter presents. The treated water is then passed through sand filters to remove 99% of particles in the cryptosporidium and giardia size-range. The water treatment procedures mainly targeted the parasites. The treated water is then supplied to many different households for use.
On 15 July 1998, Sydney water conducted a routine water sampling and the test results indicated that there was a trace of both Cryptosporidium and Giardia parasites in the water that was taken from the outlet at the Potts hill reservoir and the prospect distribution chamber. At this time the level of these parasites in the water was very little. The level of the parasites in the water increased in July to September 1998 in Sydney, Australia (Clancy, 2000 pg 55). The water in the distribution channel was highly contaminated with cryptosporidium and, giardia. Three boil-water notices were issued to the people in Sydney and an investigation was set to be carried out by the Sydney water inquiry that was formed. After the research, the results obtained confirmed that water was contaminated. The limnological evidence that was obtained from the supply system shows the same information as the results obtained from the cryptosporidium and giardia microbiological analyses. The results imply that the water supplied was contaminated during high rainfall season and the parasites penetrated from the storage reservoir into the treatment plant in a series of pulses which reacted with water.
Engineering, failure qualification
The main problem occurred in the distribution of contaminated water. The water was contaminated during the high rainfall season in which the parasites in the storage reservoir penetrated into which lead to the contamination of the water. The engineers failed to provide proper barriers that should avoid the risk during the rainy season. They presumed that the barriers issued by the storage reservoir and use of modern filtration plant will help to avoid contamination risk. They were supposed to manage and ensure that treated water is not contaminated under any circumstances.
Regular cleaning of the water pipes and proper barriers or safety measures should be established to ensure that treated water is not contaminated. The treated water in the plant should be well placed and covered to avoid contamination from water containing the parasites during the rainy season.
- Barriers that should have been in place
The Sydney water crisis could have been avoided if there was proper maintenance of the water treatment plant and regular testing of the water.
According to Cox et al (2008 p.156) water management is a crucial aspect and should be treated with a lot of care. The lesson learned is that is very important to test all the water before it is distributed to the people for use. It is also important to clean the pipe used to distribute the water and important measures should be taken so as to avoid the contaminated to enter into the treated water in the plant.
- Changes or improvements implemented
According to Davies and Wright (2014 p.456) due to the water crisis, the Sydney catchment authority was formed to take full responsibility on the management of Sydney’s catchments and dams while the responsibility of treating and distributing water was assigned to the Sydney water. Also they had the responsibility of collecting, treating and disposing sewage.
The risk was the exposure of the population to the drinking water crisis which was contaminated with Cryptosporidium and Giardia. The consumption of the contaminated water could lead to diseases and also the loss of lives.
The causal chain for the Sydney water crisis is in appendix 1
A risk assessment was conducted to verify the magnitude of the risk of the exposure to contaminated water.
The Sydney water crisis was not tragic as there were no casualties reported. The contamination of water with the cryptosporidium and giardia would have led to diseases and even loss of life if the people consumed the water. The risk occurred due to poor management of the plant. The engineers failed to consider the possible risk that could have been encountered during the rainy season. The cost of management could have increased to improve the water quality, treatment and distribution of the water. A regular water test should be put in consideration and pipes used in distribution should be cleaned to avoid the contamination of the water.
Large and localized: The Bhopal Gas Tragedy
The Bhopal gas tragedy is among the extreme industrial mishaps in the world. The poisonous gas that leaked from the factory led to thousands loss of lives and left other people with serious injuries (Sriramachari, 2004 p.914). The tragedy happened on 2nd December during the night at the pesticide industry in Bhopal Madhya Pradesh, India, and the industry is known as Union Carbide India Limited. More than five hundred thousand individual were exposed to the poisonous gas. The state verified a total of 3787 deaths correlated to the poisonous gas release and 558125 injuries; this includes 38900 severe and permanently disabling injuries and 38478 temporary partial injuries.
Engineering failure qualifications
In the early days in December the safety measures related to the methyl isocyanate plant, were not functioning accordingly. It implies that the management of the valves and lines was poor such that they were in a bad condition. The steam boilers and vent gas scrubbers which are supposed to clean the pipes had been out of service for some time. The release of the poisonous gas was the result of water that entered the pipe into the tank that caused an exothermic reaction. Engineers fail to ensure that the safety system is well managed and in good condition.
According to Mittal (2016 p. 1081) the Bhopal gas tragedy could have been avoided if the system in the plant was well managed and the employees are well educated on how to handle the pipes to prevent water from penetrating into the MIC tanks. Also, the incident could have been avoided if only the plant had places sensors which would cause an alarm when there is a gas leakage to allow engineers to take immediate action to avoid further tragedy.
- Barriers that should have been in place
The Bhopal gas tragedy could have been avoided if a maintenance plan was in places, consisting of a regular inspection of the safety systems of the plant, appropriate maintenance on the plant and proper education to the employees on how to take safety measures when cleaning the out pipes with water to avoid the water from entering into the MIC tank.
The Bhopal gas incident is among the extreme tragedy in the world. Many people lost their lives and others suffered serious injuries that led to permanent disability. Any plant that has the risk of producing toxic gas should have safety measures on how to prevent and deal with the exposure of the poisonous gas before affects the people (Gupta, 2002 p.3). The main lesson learned from the tragedy is the need of proper maintenance of the plan and proper education to the employees on how to prevent the water from entering the MIC tank when cleaning the pipes. Also, proper methods of cleaning the pipes should be implemented to avoid such human factors that can lead to disaster.
- Changes or improvements implemented
The plant was closed completely after the incident.
The risk involved is the exposure of a poisonous gas from the union carbide plant to the population around leading to thousands loss of lives and other people sustained severe injuries.
The causal chain for the Bhopal gas tragedy is in the appendix
A risk assessment was conducted to verify the magnitude of the risk caused by the exposure of the poisonous gas to the people.
Bhopal gas disaster is among the worst tragedy in the world. Over three thousand people lost their lives while more than five thousand people suffered severe permanent injuries and temporary injuries. Poor management of the plant and employee lack of knowledge on how to work under such a plant led to the tragedy (Palazzi et al, 2015 p.41). The plant could have avoided the tragedy if only they increased the cost of maintenance of the plant and employed skilled personnel to work in the plant. The plant should have implemented the modern technology by using computers in monitoring the plant and raise an alarm when there is a leakage of any harmful gas. The employee should be educated on how to work in the plant to avoid water from entering the tank so as to avoid such a tragedy. Cost should be planned on ensuring the plant has proper safety measures on cleaning the pipes to avoid human error.
Clancy, J.L., 2000. Sydney's 1998 water quality crisis. American Water Works Association. Journal, 92(3), p.55.
Cox, P., Fisher, I., Kastl, G., Jegatheesan, V., Warnecke, M., Angles, M., Bustamante, H., Chiffings, T. and Hawkins, P.R., 2003. Sydney 1998—lessons from a drinking water crisis. Journal?American Water Works Association, 95(5), pp.147-161.
Davies, P.J. and Wright, I.A., 2014. A review of policy, legal, land use and social change in the management of urban water resources in Sydney, Australia: A brief reflection of challenges and lessons from the last 200 years. Land Use Policy, 36, pp.450-460.
Gupta, J.P., 2002. The Bhopal gas tragedy: could it have happened in a developed country?. Journal of Loss Prevention in the process Industries, 15(1), pp.1-4.
Mittal, A., 2016. Retrospection of Bhopal gas tragedy. Toxicological & Environmental Chemistry, 98(9), pp.1079-1083.
Palazzi, E., Currò, F. and Fabiano, B., 2015. A critical approach to safety equipment and emergency time evaluation based on actual information from the Bhopal gas tragedy. Process safety and environmental protection, 97, pp.37-48.
Sriramachari, S., 2004. The Bhopal gas tragedy: An environmental disaster. Current Science, 86(7), pp.905-920.
Stein, P.L., 2008. The great Sydney water crisis of 1998. Water, air, and soil pollution, 123(1-4), pp.419-436.
Webb, A.A. and Martin, P.V., 2016. Potential of payments for ecosystem services scheme to improve the quality of water entering the Sydney catchments. Water Policy, 18(1), pp.91-110.