All posts by Kim Smiley

Mechanical engineer, consultant and blogger for ThinkReliability, obsessive reader and big believer in lifelong learning
Root Cause Analysis - Incident Investigation

Sinkhole Forms Under Orlando Resort

By Kim Smiley

On Sunday August 11, 2013, guests at a resort near Orlando, Florida woke to creaking sounds and breaking windows.  About 10 minutes after the disturbances began a portion of the luxury resort villa was swallowed up by a sinkhole that had formed with little warning.  Luckily, there was enough time to evacuate the resort and no one was injured, but guests lost most of their luggage, including purses and wallets, and the resort obviously suffered significant damage.

This incident can be analyzed by building a Cause Map, or visual root cause analysis.  A Cause Map shows the cause-and-effect relationships between the different causes that contributed to an issue.  This can help guide an investigation and is useful when developing solutions to prevent similar problems from occurring in the future.  Cause Maps can also be used to help explain the issue to somebody who was not involved with the investigation.  To view a high level Cause Map of this specific issue, click on “Download PDF” above.

A sinkhole forms when a void is created underground and the earth ceiling over the void collapses into it.  Voids typically form when there is a limestone or similar rock deposit underground that is dissolved by slightly acidic groundwater.  This region in central Florida is well known for sinkholes because these types of underground deposits are relatively common in the area.  Over pumping of groundwater can also cause the ground to settle, possibly forming a void.  There is concern that the rapid pace of development in this area has had an impact on the groundwater and may potentially be helping fuel the formation of sinkholes.  There was also record rain fall in July in Orlando and the additional water may have caused the ceiling over the void to be heavier than normal and more likely to collapse.

There rarely are easy answers, but sinkholes seem to be a particularly tricky problem to solve.  They are unpredictable and there is typically little warning before they develop.  Prior to the resort being constructed, the site underwent geological testing and the ground was found to be stable so something more than basic geological testing will be needed to solve this problem.  Well planned development and careful management of ground water may help limit the development and impact of sinkholes, but there will be strong economic pressure to develop more and more land in the booming Orlando area.  Insurance seems to be one of the best solutions to date.  Florida law requires insurance companies to cover “catastrophic ground collapse” so that property owners at least have an economic safety net in the event of a sinkhole.  The only good thing about sinkholes is that they generally take a little time to form like the recent resort sinkhole.  There will be property damage from sinkholes in the future, but hopefully there will also be time to evacuate everybody like there was this case.

Root Cause Analysis - Incident Investigation

Thousands Injured Each Year From Falling Televisions

By Kim Smiley

Nearly all parents know about the dangers of watching too much television, but a new study shows that too few are aware of the risk of injury from televisions.  The number of television injuries is more than most would guess with more than 17,000 children visiting emergency rooms for  television related injuries each year.   Falling televisions have also caused hundreds of deaths with 29 killed in just 2011.  The rate of injuries associated with televisions is also increasing at an alarming pace, jumping 126% since 1990.

The majority of victims were young children under five.  The accidents seem to be a potentially deadly combination of their lack of situational awareness and unanchored televisions set on unsafe surfaces.  The study didn’t include why the televisions were in unsafe locations, but one theory is that many older televisions are moved into secondary locations that aren’t as safe as families acquire bigger, fancier televisions.  The older televisions may be on dressers or night stands that were never meant to hold televisions.  Children climb the furniture either attempting to turn on the television or retrieve something off the top and the television tumbles down on top of them.  Dressers with drawers are particularly dangerous because children may figure out how to use the drawers as steps and manage to climb much higher than anticipated.

The rapid rate of technological advances may also play a role since typical families are buying new televisions more frequently than in previous decades and the number of televisions in an average home has increased.  The changing design of televisions is also relevant.  New thinner televisions have significantly smaller bases making them top heavy and more likely to topple over.  Many families are also buying bigger televisions with can amplify the danger if they topple.

Experts have suggested a few potential solutions to this problem.  First and foremost, parents need to be made more aware of the issue, possibly through a public awareness campaign.  A campaign to distribute anchoring devices has been discussed as well as providing them with new televisions at purchase.  Another option may be to add stability requirements to new designs so that televisions are less likely to topple.  It is also recommended that parents never store remote controls or toys on top of a television because they may entice children into climbing to reach them.  Only time will tell which solution if any are implemented, but this study is a first step in raising public awareness about this issue.

To view a Cause Map, or visual root cause analysis, of this issue, click on “Download PDF” above.  A Cause Map visually lays out the causes that contribute to a problem to show the cause-and-effect relationships and can help clarify a situation.  The possible solutions are included on the Cause Map.

Root Cause Analysis - Incident Investigation

Train Derailment Kills 79 in Spain

By Kim Smiley

On July 24, 2013, a train carrying 247 people violently derailed near Santiago de Compostela Spain.  Over 130 were injured and 79 were killed as a result of the accident.  Many details are still unknown, but investigators have determined that the train was traveling about twice the posted speed over a curved section of track.

The derailment was the worst train accident Spain has suffered in 40 years.  Obviously, an investigation is underway and authorities are eager to identify what caused the accident and are working to prevent anything similar from occurring in the future. One of the ways this accident can be analyzed is by building a Cause Map, a visual format for performing a root cause analysis.  A Cause Map visually lays out the different causes that contributed to an accident in an intuitive format that shows the cause-and-effect relationships.

The Cause Mapping process begins by filling in the basic background information for an issue as well as identifying how the incident impacted the goals.  In this example, the safety goal is clearly impacted because there were fatalities and injuries.  The schedule, labor, and material goals were also impacted because of the time and resources needed to investigate and clean up the accident and the damage to the train.  The negative publicity surrounding the accident can also be considered an impact to the customer service goal because people may be hesitant to ride trains if they have concerns about safety.

So why did the train derail?  The train was going too fast to safely navigate a curved section of track.  The train was going fast because it had previously been running on track designed for high speed trains where high speeds were permitted and it didn’t slow down as it entered a section of track where the posted speed was lower.  Operator action was required to slow down the train and it appears that the operator failed to take action.   Investigators are looking to whether there was a mechanical problem of some kind that prevented the train from reducing speed, but early indication is that the operator simply failed to brake and reduce the speed of the train.

A number of factors seem to have contributed to this deadly error by an experienced train operator who was familiar with this portion of track.  European Rail Traffic Management System (ERTMS) automatically controls braking and is installed on most of the track high speed trains operate on in the region, but not on the track where the accident occurred.  The accident occurred at the first potentially dangerous curve after the transition to  track where operator action is necessary to brake the train.  Based on statements by the driver,  he missed the transition to  the track where manual braking is required and didn’t realize that the train was in danger.  It has also come to light that the train driver was on the phone with the train’s ticket inspector immediately prior to the derailment and this distraction likely played a role in the accident.  The initial investigation findings have led to the train’s driver being provisionally charged with multiple counts of homicide by professional recklessness on 28 July 2013.

Regardless of whether the driver is convicted on the charges, the automatic systems involved should be a focus of the investigation.  The safety system sent a warning to the operator about the high speed prior to the accident, but it failed to prevent the accident.  Investigators need to review the timing of the warning and determine whether it came too late.  Other automatic systems such as the ERTMS also have the ability to stop a train that is operating at unsafe speeds, which raises the question of whether the safety systems used on this portion of track are adequate since the accident happened.  Ideally, a single error by a train driver for any reason won’t result in dozens of deaths.

To view a high level Cause Map of this incident, click on “Download PDF” above.  Click here to view a video of the accident.

Root Cause Analysis - Incident Investigation

Deadly Plane Crash at San Francisco Airport

By Kim Smiley

On July 6, 2013, Asiana Airlines Flight 214 crashed while attempting to land at the San Francisco International Airport. Three people have died as a result of the crash and around 180 others were injured, 13 critically. The cause of the crash is currently under investigation, but there were no obvious mechanical issues and the weather was near perfect.

Even though the investigation is still in its infancy, an initial Cause Map can be built to document what is known now about the accident and it can easily be expanded later as more information becomes available. A Cause Map is a visual format for performing a root cause analysis that intuitively lays out the different causes for an accident. The first step in the Cause Mapping process is to fill in an Outline with the basic background information for an issue. On the bottom half of the Outline there is space to document how the problem impacts the overall goals. This is useful because it helps everyone involved in the process understand the big picture and the issues with the more significant impacts can be prioritized first.

There is also space on the Outline to list anything that was different or unusual at the time the problem occurred. It’s important to note any differences because they are usually worth exploring during an investigation because they may have played a role in the accident. In this specific example, this was the first time the pilots had worked together and the two main pilots were both in unfamiliar roles. The pilot landing the plane had limited experience with Boeing 777s even though he was an experienced pilot and this was his first time landing this type of aircraft at the San Francisco airport. There was another pilot instructing him, but it was his first flight as an instructor.

Once the Outline is completed, the next step is to ask “why” question and add the answers to the Cause Map. In this example, we know that the airplane was coming in too low and too slow to land safely, but it isn’t known why that happened. The NTSB has initiated an investigation and the results will reported when the analysis is complete. Some of the early speculation is that there may have been an equipment failure, mismanagement of automated systems or ineffective communication in the cockpit. The fact that this crew was different than the typical staffing has been a focus of investigators, but it isn’t known what role they may have played in the crash.

Another piece of this puzzle is that one of the passengers who died at the crash scene appears to have been killed when she was run over by a fire engine. She was covered in foam on the ground and the firefighters were unaware of her location. Emergency response procedures will need to be reviewed as part of the investigation into this accident to ensure that first responders can do their jobs in the safest way possible.

To view an initial Cause Map of this issue, click on “Download PDF” above.

 

Root Cause Analysis - Incident Investigation

A Potentially Stinging Situation – Jellyfish Blooms

By Kim Smiley

Jellyfish are some of nature’s most impressive survivors.  They have been around since long before the dinosaurs roamed the earth and continue to thrive.  In some cases, they may even be thriving a little too successfully.  Massive jellyfish blooms can flourish in the right environment and can decimate other species and cause significant damage.

Naturally occurring jellyfish blooms have been around for ages and while they may be inconvenient at times, they aren’t particularly alarming.  The real concern is that manmade conditions may lead to the growth of jellyfish blooms at times or regions that wouldn’t normally see them.  Large numbers of jellyfish can cause a number of serious issues.  Safety is a concern because jellyfish stings are painful and can even be deadly.  Regions that depend on tourism can also be impacted because travelers may avoid areas with large numbers of jellyfish.  Jellyfish have caused damage to ships and buildings when they clog intake lines.  Populations of other species have also been decimated in some areas by jellyfish blooms which can affect commercial fishing operations.

What causes these jellyfish blooms can be explored by building a Cause Map or visual root cause analysis.  A Cause Map intuitively lays out causes that contribute to an issue and shows the cause-and-effect relationships between them.  In this example, the jellyfish blooms grow because jellyfish are well suited for life in low oxygen “dead zones” that are being created in the ocean.

It all starts with fertilizer containing nutrients running into the ocean.  An algae bloom forms as algae feed on the nutrients.  Eventually the nutrients are depleted and the algae dies off leading to the growth of a bacterial bloom as bacteria feed on the dead algae.  The bacterial bloom depletes the oxygen making the region unsuitable for most species.  However, the opportunistic jellyfish can survive and even thrive in low oxygen levels.  Jellyfish are able to rapidly grow and reproduce quickly so the population surges upward in an environment with few predators and little competition.

A few facts so that the reproductive abilities of jellyfish can be fully appreciated: a single female jellyfish can release tens of thousands of eggs per day, and jellyfish are able to double their weight in a single day if food is abundant.

Eating habits of jellyfish also make it very difficult for other species to move back into the region even if oxygen levels increase.  Jellyfish not only compete for the same food as larvae of other species, plankton, they are fond of eating larvae and eggs.  It’s difficult to compete with a species that is both a predator and competitor.

Before anyone has nightmares of huge jellyfish causing wide scale destruction, I should note that researchers have not found evidence that jellyfish are in danger of overrunning the oceans.  But many scientists do believe that human activities have contributed to jellyfish blooms growing in localized areas.  It’s always worth trying to understand how human activities are impacting our environment, especially when a species so well equipped for survival is involved.

To view a high level Cause Map of this issue, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Chemical Plant Explosion Kills 2 and Injures Dozens in LA

By Kim Smiley

On June 13, 2013, an explosion at a chemical plant in Louisiana killed two and injured more than seventy others.  The cause of the explosion is still unknown, but the federal Occupational Safety and Health Administration and the U.S. Chemical Safety Board are investigating the accident.

Even though the investigation is still ongoing, an initial Cause Map, or visual root cause analysis can be built for this issue.  The initial Cause Map can document what is known at this point and can easily be expanded to incorporate more details as they become available.  The first step in the Cause Mapping process is to fill in an Outline with the basic background information for the accident (such as the location, time and date) as well as document what overall goals were impacted by the incident.

In this case, the safety goal was obviously impacted because of the fatalities and injuries.  The damage to the plant is an impact to the material goal and the time the plant is shut down is an impact to the schedule goal.  Once the Outline is complete, including the impacts to the goal, the Cause Map is built by asking “why” questions.  For example, we would ask “why” people were killed and injured and would add that there was an explosion at the chemical plant to the Cause Map.

What caused the explosion isn’t known, but every explosion requires oxygen, a spark and fuel so these basic facts can be added to the Cause Map.  The plant housed a large amount of flammable material because it manufactures polymer grade propylene which is used to make plastics.  If investigators are able to determine what created the spark that information could be added as well as any other relevant information that comes to light.

The Outline also has space to document anything that is different or unusual at the time of the accident.  Anything unusual about the situation when the accident occurred is often a good starting point in an investigation because it may have played a role in the accident.  In this example, the plant was being expanded at the time of the accident and there were many contract workers on site.  If this is found to have played a role in the accident, this information would be incorporated onto the Cause Map as well as the Outline.

The final step of the Cause Mapping process is to use the Cause Map to develop solutions that can be implemented to help prevent a similar problem from occurring in the future.  Once a final Cause Map is built that incorporates all the findings from the investigation, it will be helpful in understanding any lessons to be learned and discussing potential solutions.

To view a high level Cause Map and an Outline for this accident, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Bridge Collapse In Washington Dumps Cars in River

By Kim Smiley

On May 23, 2013, a section of a four lane bridge over Skagit River near Mount Vernon, Washington unexpectedly collapsed, sending two cars into the river.  No one was killed, but the bridge failure is going to take months and an estimated $15 million to repair.  Additionally, the bridge was one of Washington’s main arteries to Canada with around 70,000 vehicles crossing it a day and detours during the repairs are significantly impacting the region.

So what caused the bridge to fail and how can a similar collapse be prevented in the future? This issue can be analyzed by building a Cause Map, a visual root cause analysis.  A Cause Map intuitively shows the causes that contributed to an issue and the cause-and-effect relationships between them. The collapse occurred after the top of an oversized truck hit a steel girder.  The bridge was a ‘fracture critical’ design, meaning that the design had little redundancy and fracture of one critical component, in this case the overhead steel girder, caused the whole bridge to collapse.  This type of design was common when the bridge was built in the 1950s because it was relatively quick and cheap to build.  Newer designs typically incorporate more redundancy to prevent a single failure from causing significantly damage, but the average bridge in the United States is 42 years old and there are thousands of fracture critical bridges across the nation.

So why did the truck impact the bridge?  This question is more complicated than it might appear on the surface.  The driver appears to have done his due diligence, but he had no warning that his truck was taller than the clearance.  The driver had a permit for hauling an oversized load on this stretch of highway.  The truck was also following a guide who gave no indication of potential clearance issues.  Additionally, there was no sign about low overhead clearance on the bridge because signage wasn’t required.  Signs are only required for overcrossing less than 14 feet and the lowest point on the bridge was higher than that.

The truck was traveling in the outside lane at the time it impacted the bridge.  The clearance over the outside lane of the bridge is lower than the inside lane because of the arch design of the bridge.  The truck’s load was 15 feet 9 inches high and the lowest clearance over the outside lane was 14 feet and 7 inches, but the inside lane has about a 17 feet clearance.  Bottom line, if the truck had simply moved into the inside lane it should have had the clearance to safely cross over the bridge.

This incident is certainly a warning about the need for redundancy in designs, but it also illustrates the need for clear communication.  If the driver had been aware that there was a potential issue, he could have changed lanes (which is a free and relatively easy solution) and the bridge collapse wouldn’t have happened.  Something needs to be changed to ensure that drivers are aware of any potential clearance issues.  In an ideal world, all bridges would be the safest, most up to date designs available, but the reality is that there are thousands of “fracture critical” bridges in use throughout the United States and we’re going to have to find ways to use them as safely as possible for quite some time.

Click here to see a Cause Map of another bridge failure, the 2007 I-35 Bridge Collapse and here to see a Cause Map of the failure of the Tacoma Narrows Bridge.

Root Cause Analysis - Incident Investigation

The Deadliest Airship Crash in History Wasn’t the Hindenburg

By Kim Smiley

Many people have heard of the Hindenburg, but have you heard of the USS Akron?  The Hindenburg crashed in 1937, killing 35 people. The USS Akron crash four years earlier killed 73, making it the deadliest airship crash in history.

The crash of the USS Akron can be investigated by building a Cause Map, a visual format for performing a root cause analysis.  A Cause Map is built by asking “why” questions to determine what causes contributed to an issue.  The causes are organized on the Cause Map to illustrate the cause-and-effect relationships between them.  Why were 73 people killed?  This occurred because they were onboard the USS Akron, the airship struck the ocean surface, the crew had little time to brace for impact and there were insufficient flotation devices onboard.

The crew was onboard the USS Akron because the airship was operated by the US Navy and was performing a routine mission at the time of the crash.  The airship hit the ocean because it was operating over the ocean and lost altitude in a severe storm.  Why was the airship operating in a storm?  There was no severe weather predicted at the time and a low pressure system unexpectedly developed.  The crew had little time to brace for the impact because they weren’t aware that an impact was imminent.  There was low visibility at the time because it was a stormy, dark night. The barometric altimeter was also showing that the airship was higher than it actually was.  Barometric altimeters are affected by pressure and the low pressure in the storm impacted more than the crew realized.   The lack of life jackets and other floatation devices also contributed to the high number of deaths.  There were no life jackets onboard the airship at the time of the crash and only one rubber raft.  The safety equipment had been given to another airship and had never been replaced.

While few of us plan to operate or build an airship anytime in the near future, the important of keeping sufficient safety gear onboard any vehicle of any kind is an important lesson.  Lack of safety gear is a reoccurring theme in many historical disasters.  For example, the sinking of the Titanic would be a very different story if there had been sufficient lifeboats onboard.  This example might be very different if the crew had been wearing life jackets.  The airship would still have been lost, but there would likely have been fewer casualties.

To view a high level Cause Map of this example, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Collapse of Salt Mine Creates Massive Sinkhole in LA

By Kim Smiley

On August 3, 2012, a massive sinkhole appeared in Assumption Parish, Louisiana that continues to grow and evade easy answers.   About 150 homes were evacuated and residents are still displaced more than seven months later.

What caused a sinkhole to form overnight?

That question can be answered by building a Cause Map, a visual root cause analysis.  In the Cause Mapping process, the first step is to fill in an Outline with the background information for an issue as well as how the problem impacts the goals.  In this example, the sinkhole impacts several goals including the environmental goal, the safety goal because there is a potential for injuries, the financial goal because of the costs associated with the emergency response and remediation of the issue, and the customer service goal because 150 homes have been evacuated for an extended time.  Once the Outline is completed, the next step is to ask “why” questions to find the different causes that contributed to the problem being analyzed.

So why did the sinkhole form?  The sinkhole formed when an underground salt mine collapsed.  This happened because there was a salt mine in the area and a wall of the mine failed.  Salt was mined in the area because there was a large deposit of salt underground and salt mining is profitable since it is used in a wide range of industries.  The wall collapsed because it was too thin to support the pressure because the mine was inadvertently located too close to the edge of the salt deposit.  The mine ended up too near the edge because the location of the salt deposit wasn’t accurately known.  It’s difficult to access salt deposits thousands of feet underground and the mine was permitted in 1982, using 1960s maps of the salt deposit, using technology that was limited compared to what is used today.

There is also a potential for injuries associated with the sinkhole both because it continues to grow and because there is a risk of explosion from the natural gas being released.  The sinkhole has given the underground pockets of natural gas a pathway to the surface. Workers are trying to minimize the danger by flaring the gas off and ensuring there isn’t anywhere it can build up.

The financial impacts of this issue are substantial, both to the community and the mining company.  The salt mining company is in negotiations to buy out the displaced residents and has been providing financial support to them during the evacuation.  The costs of the emergency response are also adding up, not to mention the cost of whatever remediation is necessary once the area becomes stable and the full extent of the issue is known.

The final step of the Cause Mapping process is to develop solutions to prevent the problem from reoccurring.  This is still an ongoing issue, but some steps have already been taken to help prevent future sinkholes from forming.  Advances in technology have already improved understanding of underground deposits and will help in locating future mines.  Another possible solution is regulation changes to require mines to be located farther from the edge deposit.

To view an Outline and a high level Cause Map for this issue, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Plan to Control Invasive Snakes with Drop of Dead Mice

By Kim Smiley

Brown tree snakes are an invasive species that was inadvertently introduced to Guam where they have decimated native bird populations and done massive environmental damage.  It’s estimated that there are about two million of these snakes  on the island.  The newest plan of attack in the battle to control the brown tree snake population is to poison the snakes by parachuting dead mice laced with pain killers onto Guam.

The problem of invasive brown tree snakes can be analyzed by building a Cause Map, a visual root cause analysis.  A Cause Map is built by asking “why” questions and adding the causes to intuitively show the cause-and-effect-relationships.  The first step is to identify the goals that are impacted.  In this example, the environmental goal is impacted because the balance of native species on Guam has been altered.  This has happened because the native bird population has been decimated because they have been eaten by an invasive predator, the brown tree snake.  The spider population has also exploded because many of the birds, their main predator, have disappeared.  The snakes also cause significant and expensive power outages on Guam as they climb into electrical equipment.

Brown tree snakes have taken over Guam for several reasons.  First, the snake was accidently introduced to the island, likely as a stowaway in military cargo after World War II.  Once the snake was on the island, it thrived because the species had no major predator on the island, there was little competition for resources, and there was an abundant food source.  There was little competition because Guam had only one other snake species prior to the introduction of the brown tree snake.  The native snake species is blind and significantly smaller, preying mostly on insects.  The brown tree snake had ample food because it is a pretty flexible predator happy to eat birds, lizards, bats and small mammals.  In fact, the brown tree snake has found Guam so hospitable that the snakes grow larger on Guam than in their native habitat where predators are more plentiful and food is more limited.

Presence of these snakes on Guam has caused massive damage.  Nine of twelve native bird species are extinct on the island.  The snakes have also eaten a significantly amount of the small mammal population.  There has also been a huge impact on vegetation on Guam since the snakes have wiped out many of the pollinators.  Scientists have been trying to find ways to improve the situation.

The newest plan involves dropping dead mice laced with pain killers onto Guam.  The pain killers are deadly to the snakes if ingested.  The mice will be attached to something called a flagger, which is two pieces of cardboard attached with a streamer.  The flagger should act like a parachute and catch in the tree canopy, which is where the snakes predominately spend their time.  The hope is that the snakes will then eat the pain killer laced mice, thus reducing their population.  The current plan is to drop about 2,000 mice over an enclosed area to determine if this is an effective method of brown tree snake population control.  If it works, more dead mice could be headed Guam’s way in the future.

To view a Cause Map of the brown tree snake problem and a Process Map of the plan to drop dead mice, click on “Download PDF” above.  To view a similar example about controlling feral cats on Macquarie Island, click here.