Tag Archives: Collapse

Root Cause Analysis - Incident Investigation

Crane Collapse In High Winds Kills One in NYC

By ThinkReliability Staff

A crane collapsed in New York City on February 5, 2016 killing one, injuring three, and damaging two city blocks. While an investigation is underway and the causes of the crane collapse have not yet been determined, the city has already implemented new rules to make crane operations safer. We can examine the potential cause-and-effect relationships that led to the issue in a Cause Map, or visual root cause analysis.

We begin by capturing the what, when and where of the incident within a problem outline. The crane collapse occurred February 5 at about 8:30 a.m. Anything that is different or unusual at the time of an incident should also be noted on the outline and an important difference on February 5 was the accelerating winds. The crane that collapsed was a crawler crane, and at the time of the collapse, workers were in the process of securing the crane because of the high winds. This was as expected. Says New York City Mayor Bill de Blasio, “The workers on Friday morning did not begin work on the site, but immediately seeing the winds, made the move to secure the crane, so their timing was appropriate. Upon arrival, they immediately determined the need to secure the crane.”

The impact to the goals as a result of the incident are also captured in the problem outline. In this case, the safety goal was impacted due to the death, as well as injuries. The environmental goal was impacted by water leaks resulting from damage. Customer service (looking at the citizens of New York City as customers) is impacted due to closures. Production is impacted because 418 additional cranes were secured as a result of the incident. Property impacts includes damage to the crane, as well as two city blocks. The labor goal was impacted because of the time required for the response and removal of the damaged crane. It’s also important to capture the frequency of similar events. OSHA reports it has investigated 13 fatal crane accidents in the last 5 years. (There was a crane collapse in New York City in 2008 that resulted in 4 deaths. Click here to see our previous blog on this topic.)

Once the impacts to the goals have been captured, the analysis begins with one of these goals, which is an effect. Asking “why” questions allows the development of cause-and-effect relationships. In this case, the fatality and injuries resulted from the collapse of a crane. It also resulted from people being in the area of the crane collapse. Both of these causes are required (the fatality and injuries would not have occurred if the crane had not collapsed, or if people had not been in the area) so they are listed vertically and joined with “AND”.

People were in the area where the crane collapsed because the area was inadequately secured. This is likely because construction workers were responsible for securing the area, as well as securing the crane. The reasons for the crane collapse are unknown. However, the investigation will look at human error, structural and equipment problems, and impacts from high winds. While the cause has not been determined, it is considered likely that the wind played a role. The crane was not yet secured, as the workers were in the process of attempting to secure it. It was not required to be secured because city regulations limit operation of cranes when wind is above 30 miles per hour(mph), or if there are gusts greater than 40 mph. The crane operators were working under a limit of 25 mph, as sometimes manufacturers use stricter limits. The forecast did not indicate that winds would be greater than 25 mph that day.

As a result of the incident, Mayor de Blasio put into place immediate and temporary rules regarding crane operation. These rules will be in place until a task force provides updated recommendations within 90 days. Uniformed personnel will assist with enforcing closures associated with crane use. Crane operations are limited to wind speeds less than 30 mph (or gusts up to 40 mph). A city sweep and increased fines were also put into place to ensure the updated regulations are followed.

To view a one-page overview of the Outline, Cause Map and interim solutions, click on “Download PDF”.

Root Cause Analysis - Incident Investigation

Earthquake Hits Nepal

By Kim Smiley

As anyone paying any attention to the news knows, a magnitude 7.8 earthquake hit Nepal on April 25, 2015.   The same forces that created the Himalayan Mountains are still at work in the region as the Indo-Australian Plate slowly slides under the Eurasian Plate and experts have long warned about the potential for an earthquake in this location.

At least 4,600 people were killed as a result of the earthquake and the United Nations has stated that 8 million people have been affected.  Many people impacted by the disaster lack adequate water and food and are living in temporary shelters without sanitation facilities.  Beyond the sheer scope of the natural disaster, providing emergency assistance has also been difficult because some of the affected villages are in remote locations that are challenging to access and many roads were damaged by the earthquake.  The long-term economic impacts are also predicted to be large because of the significant damage to infrastructure and the fact that local economies relay heavily on tourism.

A Cause Map, a visual root cause analysis, can be built to help understand this disaster better. A Cause Map lays out the cause-and-effect relationships in an intuitive format by asking “why” questions.  In this tragic example, asking why so many fatalities occurred shows that the majority of deaths were caused by collapsing buildings.  Many buildings in the impacted area were unreinforced masonry structures that couldn’t withstand the force of the earthquake.  These buildings are cheaper and quicker to build than more modern construction that would meet building codes designed to survive an earthquake.

Civil unrest in the region has resulted in rapid urbanization and a large demand for housing as people moved into cities. Rapid and relatively unregulated urbanization in a country with one of the lowest per capita incomes in the world proved to be a deadly combination in a region prone to earthquakes. Historically a major earthquake has struck this region about every 75 years and this one had long been predicted.  Says Susan Hough, a geologist with the U.S. Geological Survey, “It was clearly a disaster in the making that was getting worse faster than anyone was able to make it better. You’re up against a Himalayan-scale problem with Third World resources.”

Every disaster and the emergency response to it should be studied to see if there are any lessons learned that can be used to save lives and minimize damage in the future. There is clearly no “solution” that can prevent an earthquake, but even when dealing with a natural disaster there are ways the impact of a disaster could be mitigated.  The possible solutions may not be cheap or easy, but it is important to remember that it is possible. You can’t stop the earthquake, but you can work to build stronger buildings.

Root Cause Analysis - Incident Investigation

Fatal Bridge Collapse Near Cincinnati

By Kim Smiley

On the evening of January 19, 2015, an overpass on Interstate 75 near Cincinnati collapsed, killing one and injuring another.  The overpass was undergoing construction when it unexpectedly collapsed onto the road below it, which was still open to traffic.

This incident can be analyzed by building a Cause Map, a visual root cause analysis, to intuitively lay out the many causes that contributed to an accident by showing the cause-and-effect relationships.  Understanding all the causes that played a role, as opposed to focusing on a single root cause, expands the potential solutions that can be considered and can lead to better problem prevention.  A Cause Map is built by asking “why” questions and documenting the answers.

In this example, a construction worker was operating an excavator on the overpass when it collapsed.  When the bridge collapsed the worker was crushed by the steel beams he was moving.   The additional weight of evacuator and steel beams on the overpass likely contributed to the collapse.   The overpass was being demolished as part of a project to remake this section of the Interstate and a portion of the overpass had already been removed.  The work that had been done appears to have made the structure of the bridge unstable, but the construction company was not aware of the potential danger so the worker was operating on top of the overpass and the road beneath it was still open to traffic.

A truck driver traveling under the overpass at the time of collapse suffered only minor injuries, but came within inches of being crushed by the bridge. It really was simple luck that no other vehicles were involved.  Had the collapse happened earlier in the day when there was more traffic, the number of fatalities may very well have been higher.  As investigators review this accident, one of the things they will need to review is the fact that the road below the bridge was open to traffic at the time of the collapse.  An additional relevant piece of information is that the construction company had financial incentives to keep the road open as much as possible because they would be fined for any amount of time that traffic was disrupted.

In addition to the safety impacts of this accident, the overpass collapse dramatically impacted traffic on a busy road with an estimated 200,000 vehicles traveling on it daily.  It took nearly a day to get all lanes of the interstate cleaned up and reopened to traffic.  No one wants to close roads unnecessarily and the goal of minimizing traffic is an excellent one, but it has to be balanced with safety.  The collapse of the overpass wasn’t an unforeseeable random accident and the demolition needs to be done in a safe manner.

Root Cause Analysis - Incident Investigation

Ceiling Collapse in London’s 112-year-old Apollo Theatre Injures Dozens

By Kim Smiley

On December 19, 2013, 76 people were injured when a large section of plaster fell from the ceiling of London’s historic Apollo Theatre.  Luckily there were no fatalities as a result, but six people were seriously injured in the accident.

The investigation is still underway, but an initial Cause Map can be built to begin analyzing the incident.  The first step in the Cause Mapping process is to fill in an Outline with the basic background information as well as formally list how the incident impacts the goals so that no part of a multifaceted problem is neglected.  It’s important to understand how an issue impacts all goals, such has safety issues, financial considerations, schedule delays, etc. There are times when different solutions can help mitigate risks to separate goals so it is useful to list all impacted goals for clarity.   Listing the impacted goals will also help focus the investigation on the most important elements.

Another very important part of the Outline is a space where any relevant differences are listed.  Anything that was different at the time an incident occurred is usually a good place to start digging during an investigation.  For this example, there was heavy rain during the hour preceding the ceiling collapse.  It’s also worth noting that the Apollo Theatre is 112 years old.

Investigators have not announced what led to the ceiling collapse, but early speculation is that rain water leaked through the roof and settled onto the plaster.  The theory is that the additional weight from the water was more than the ceiling could handle and it fell, taking a lighting rig and part of a balcony with it.   If this was the case, there will need to be hard questions asked about the adequacy of current building codes and inspection requirements.  Currently, the roof on the Apollo Theatre was only required to be inspected every 3 years.  It appears that the Theatre was up to date on and had passed all required inspections so the required periodicity may need to be re-evaluated in light of the recent failure.

Any suspected causes that haven’t been proven yet can be included on the Cause Map, but are marked with a “?” to indicated that they need additional evidence.  This helps document what has been considered during an investigation and questions that still need to be answered.

To view an Outline and the initial Cause Map of the Apollo Theatre ceiling collapse, click on “Download PDF” above.

 

Root Cause Analysis - Incident Investigation

Failure of the Teton Dam in 1976

by ThinkReliability Staff

On June 5, 1976, workers were called to the Teton Dam on the Teton River in Idaho to attempt to repair a leak.  Workers in bulldozers narrowly avoided being sucked into the dam with their equipment, and watched helplessly as the dam was breached.  It would kill 14 people and cause nearly hundreds of millions of dollars in property and environmental damage.  To examine what went wrong, we can perform a visual root cause analysis, or Cause Map.

The Cause Mapping process begins by determining the impacts to an organization’s goals.  From the perspective of the government, specifically the Bureau of Reclamation, the safety goal is impacted because of the 14 deaths.  The environmental goal is impacted due to the severe impact the dam failure and subsequent flooding had on the ecosystem of the area.  The customer service goal was impacted due to the evacuation of three towns.  The production goal is impacted due to the abandonment of the dam – at a cost of approximately $50 million.  Additionally, property damage of at least $400 million (some estimates are much higher) is an impact to the property goal.  (There were also substantial claims related to the loss of property and livelihood from impacts to industries, particularly fishing.)

Once we have determined the impacts to the goals, we begin with an impacted goal, such as the safety goal, and ask “Why” questions to determine the cause-and-effect relationships that led to the impacted goals (also known as “problems”.)  In the case of the Teton Dam failure, people were killed due to a massive wave of water released from the dam (which was filled to capacity) when it failed.  The dam failure was also the cause of severe damage to the dam, which was never rebuilt, leading to the impacted production goal.

The failure of the dam was found to be caused by erosion and inadequate strength.  Due to the less than ideal geological conditions of the site (which was picked because there were no “good” sites available), unequal stress distribution and inadequate fill material (which was used from the site) led to reduced strength.  Susceptible materials and seepage from leaks in the embankment, caused by joints that were not resistant to water pressure due to inadequate testing, and inadequate protection from water due to an over-reliance on an ineffective curtain intended to stop flow, led to the erosion.

Many geologists had predicted problems with the dam before it was built.  Specifically, in his book “Normal Accidents”, Charles Perrow states “The Bureau ignored its own data that rocks in the area were full of fissures, and in addition they filled the dam too fast . . . All it takes to bring a dam down is one crack, if that crack wets the soil within the interior portions of the dam, turning it into a quagmire.”

Although tragic, and expensive, the failure of the Teton Dam did lead to many reforms in the Bureau of Reclamation, who is responsible for dam safety.  Detailed geological studies performed in order to determine the causes of the dam failure also provided additional insight to the strength provided by various types of earth, erosion and seepage.

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

Update: Cause of Death of Schoolchildren from Tornado in Moore, Oklahoma Not Drowning

by ThinkReliability Staff

Although they are sometimes treated as a static object, Cause Maps (and any root cause analysis) can – and should – change based on updated or corrected information.  A frequent question we get asked is “What if I make a mistake on my Cause Map?”  Well, you fix it.  Let me show you how.

First, a little background on my error.  Last week, I thought it would be important and useful to demonstrate what had happened in the aftermath of Moore, Oklahoma, after a category 5 tornado hit much of the town, including an elementary school.  (See the previous blog.)  Because there are certain expectations for public safety at an elementary school, I decided to focus the analysis on the children who died at the elementary school and the causes that led to their deaths, as well as information on the potential and implemented solutions to reduce that risk.

I researched how specifically the children had died – an unfortunate necessity to ensure that the solutions are working towards the correct causes – and discovered a statement from the Lt. Gov. of Oklahoma the morning after the tornado saying that the children who died had drowned in the basement due to a burst water main.

As you can imagine, sometimes information that is relayed in the immediate scene of a disaster is not entirely accurate.  In this case, the information that the children had drowned was incorrect.  Rather, the children who died were in a classroom and died from blunt force trauma and asphyxiation (suffocation) due to being struck or covered by debris from the tornado.

Once we have verified that our initial cause-and-effect relationship is incorrect, we can correct the Cause Map.  Rather than just erasing the “wrong” causes and adding in the new causes, we suggest crossing off the causes that have been disproved with evidence.  (Click on “Download PDF” above to see an example of a corrected Cause Map.)  This way anyone who may have seen an earlier version of the Cause Map, or heard the same initial erroneous information that was used to make it, will have a clear version of what did happen, including the evidence that verifies the correct information.

Obviously the fact that the children died is tragic, so some may wonder what difference it makes exactly how they died.  Generally people who are killed in tornadoes are killed by objects striking them.   This is why tornado survival drills focus on getting to spots where there is the least possible dangerous debris, or the least risk of the debris becoming dangerous flying objects. Windowless rooms are recommended, because glass can be broken and easily turn into shrapnel.  Basements are recommended because the strong winds associated with tornados have less access to underground areas.  Bathrooms are another option because most everything in a bathroom is secured to the walls and/or floors.  In a pinch, people seek protection under heavy pieces of furniture.  (Survivors from the affected school have said that they hid under their desks and held on for dear life.)

Because the basement is a recommended sheltering location, the possibility of drowning from  equipment that may be damaged by a tornado meant that the basement needed to be reconsidered as a sheltering location.  Because the school did not have a designated safe room, during the 16-minute warning teachers got their students to anywhere they could, including, in many cases, under their own bodies for protection.  (Again, based on the extreme damage to the school the death toll, while tragic, demonstrates the remarkably quick and effective action  taken the teachers.  I can’t emphasize this enough.)  Because this protection was very likely causally related to the death toll (in that without the amazing response from the teachers the death toll may have been much higher), I added additional evidence to the cause of injury.

Be aware that changing the causes may impact the recommended solutions.  The solutions discussed in the previous blog are still valid, especially the recommendations for inclusion of storm shelters for schools in the area.  An additional clarification added in the update is that this has been required since 1999 (after this school was built).  All the schools being rebuilt as a result of the tornado damage will have storm shelters, as will schools built in the future.  Individual communities will still be faced with the choice of which buildings will and will not be required to have storm shelters, and any incentives that will be put into place to encourage their construction.

To view the Outline and Cause Map, please click “Download PDF” above.  Or click here to read more.

Root Cause Analysis - Incident Investigation

Children Killed When School Hit by Category 5 Tornado

by ThinkReliability Staff

A category 5 (the most destructive) tornado hit Moore, Oklahoma on May 20th, destroying the town and killing 24.  Of those killed, 7 were elementary school children, who drowned when water mains burst in the basement where they were sheltered.

Examining this tragedy can help provide lessons to reduce the risk of this issue happening again.  We can analyze the tornado impact at the most severely impacted elementary school in a Cause Map, in order to visually diagram the cause-and-effect relationships that led to the tragic deaths.

First, we determine the impacted goals.  In this case, all other goals are overshadowed by the deaths of seven  elementary students, and injuries to dozens.  In addition, the school was completely devastated (demonstrating the unbelievable destructive power of the tornado), resulting in early school closure and intense rescue, recovery and cleanup.

To perform our root cause analysis, we begin with the safety goal and ask “Why” questions.  The deaths in this case are reportedly due to drowning, which occurred when children in the basement (a recommended sheltering location in the case of tornadoes) drowned due to water from bursting water mains.  The specific failure mechanism of the failure is not known (and may never be due to the extreme levels of damage) but is likely related to the direct strike of the tornado, which is common in the area (close to the center of tornado alley).

Students who were injured by crushing and asphyxia were in the hallways and bathrooms of the school.  (These are recommended sheltering locations for buildings that don’t have basements.)   It is remarkable that, despite the complete annihilation of the school, students who were sheltered in hallways and bathrooms all survived, thanks in many cases to teachers protecting them with their own bodies.  A 16-minute warning from the National Weather Service combined with carefully rehearsed crisis plans that were put into action, allowed the best possible protection for students in a school without a safe room or storm shelter.

This storm has reignited the discussion about expectations for safety shelters in public places that are prone to natural disasters.  The devastating loss at the school has also raised the safety issue of ensuring that the locations used for shelter are cleared of other potential hazards, such as water mains and fire risks.  Because of the relatively short warning time (16 minutes in this case, which is above average) before a tornado strikes, emphasis on tornado drills and safety plans should continue.

To view the Outline and Cause Map, please click “Download PDF” above.  Or click here to read more.

Root Cause Analysis - Incident Investigation

Hundreds of Garment Workers Killed in Building Collapse

By ThinkReliability Staff

Hundreds are confirmed dead – with hundreds more still missing – as a result of a building collapse in Bangladesh.  The number of people who were in the building when it collapsed is unclear, due to spotty records.  Some sources have suggested the death toll may surpass 1,000.

We can examine the causes that led to the deaths in a Cause Map, which visually diagrams the cause-and-effect relationships that led to the tragedy.  First, we capture the impacts to the goals, which includes the extremely significant impact to the safety goal due to the high number of deaths as well as many other goals, including compliance, production and the impact to the labor goal resulting from the rescue and recovery operations.

The deaths were caused by the collapse of a building which was partially occupied at the time. The building housed five garment factories, as well as a bank and other shops.  Even though cracks appeared in the building   and inspectors requested evacuation and closure of the building, garment workers were ordered back to work.    The bank was evacuated, and the shops were already closed.  Despite deplorable conditions (brought to the attention first by a building fire last November and now by this tragic collapse),  workers (mainly young women)   can still be found to work in the garment industry because the average wages in the country are so low.  Eight people, including the building owner and engineers, have been charged as a result of the collapse.

The building, which was illegally built 3 stories too high, was not up to code and not approved by the government.  The building was built on wetland and used substandard materials for construction. As a result of this collapse, the government has said it will form a committee to ensure the safety of buildings and workers.  Shops in the US and Europe that sell garments produced in Bangladesh have distanced themselves from the companies housed in the buildings while many consumers call for more oversight from these companies, who utilize cheap labor in Bangladesh to create their goods.  The garment industry accounts for 77% of Bangladesh’s exports.

It is hoped that this recent tragedy will increase the attention paid to worker safety by the government within Bangladesh as well as consumers who buy the end product abroad.

To view the Outline and Cause Map, please click “Download PDF ” above.

Root Cause Analysis - Incident Investigation

Deadly Kansas City Walkway Collapse

By Kim Smiley

On July 17, 1981, the second and fourth floor suspended walkways collapsed at the newly opened Hyatt Regency of Kansas City, Missouri.  A dance contest had attracted a crowd and the atrium under the walkway was filled with people.  This accident killed 113 people and injured 186.

The hotel was newly constructed and the walkways were well maintained.  So how did this happen?

A root cause analysis of this accident shows that there were a number of causes that contributed to the walkways collapsing.  Investigation into the accident shows that the structural design of the walkway was inadequate.  A weld failed which allowed a support rod to pull through the box beam and the walkways fell.

Additionally, the weld had greater stress than normal on it at the time of the failure because a large crowd had gathered to watch a danced content.  About 20 people were on second floor walkway and about 40 were on the fourth floor walkway at the time of the accident.  The higher loading combined to the walkway collapse.

Identifying the failure mechanism is important during an investigation, but a thorough root cause analysis needs to take the analysis farther to really understand the causes.  The reason that an inadequate design was built needs to be determined.

In this case, it appears that the design was changed without approval of the structural engineer.  This resulted from a communication error between the fabricator and the structural engineer.  The structural engineer sent a sketch of a proposed walkway design to the fabricator, assuming that the fabricator would work the details of the design himself. The fabricator assumed the sketch was a finalized drawing.   The fabricator then picked standard parts to fit the sketch.  This resulted in a significant change from the original design and dramatically decreased the load bearing capacity of the walkways.

The original design called for continuous hanger rods (a non-standard part that would have needed to be manufactured) that passed through the fourth floor walkway beam box to the second floor walkway, resulting in the ceiling connecting supporting the weight of both walkways.  The fabricator changed the design to use two shorter rods (standard parts) which resulted in the fourth floor walkway supporting the weight of the second floor walkway, which it wasn’t designed to handle.

It’s important to investigate beyond the point of inadequate design to learn what failed in the design process to prevent future accidents from occurring.