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

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

Concrete slab smashes truck killing 3

By Kim Smiley

On April 13, 2015, a large section of a concrete barrier fell from an overpass onto a truck in Bonney Lake, Washington. A couple and their baby were in the vehicle and were all killed instantly. Investigators are working to determine what caused this accident and to determine why the road under the overpass remained open to traffic while construction was being done on the overpass.

A Cause Map, a visual method of root causes analysis, can be built to help understand this accident. More information is still needed to understand the details of the accident, but an initial Cause Map can be created now to capture what is known and it can be easily expanded to include additional information as it becomes available. A Cause Map is created by asking “why” questions and visually laying out the answers to show the cause-and-effect relationships. (Click here to learn more about basics of Cause Mapping.)

In this accident, three people were killed because the vehicle they were riding in was smashed by a large slab of concrete. The vehicle was hit by the concrete slab because it was accidently dropped and the truck was under the overpass at the time it fell because the road was open to traffic. (When two causes are both needed to produce and effect, the causes are listed on vertically on the Cause Map and separated by and “and”.) The road would typically have been closed to traffic while heavy work was performed on the overpass, but the work plan for the construction project did not indicate that any heavy work would be performed on the day of the accident.   At some point the actual work schedule must have deviated from the planned schedule, but no change was made in plan for managing traffic resulting in traffic traveling under the overpass while potentially dangerous construction was performed.

Investigators are still working to understand exactly why the concrete slab fell, but early indication is that temporary metal bracing that was supporting the concrete may have failed due to buckling. The concrete barrier on the overpass were being cut into pieces at the time of the accident so that they could be removed as part of a $1.7 million construction project to improve pedestrian access which included adding sidewalks and lights.

Once the details of what causes this tragic accident are better understood, solutions can be developed and implemented that will help reduce the risk of something like this happening again. To view a high level Cause Map of this accident, click on “Download PDF” above.

You can also read a previous blog “Girder Fell on Car, Killing 3” to learn more about a similar accident that occurred in 2004.

Root Cause Analysis - Incident Investigation

Houston Ship Channel Closed After Ships Collide

By Kim Smiley

On March 9, 2015, two large ships collided in the Houston Ship Channel, one of the busiest waterways in the United States.  There were no major injuries reported, but the accident resulted in the release of methyl tertiary-butyl ether, commonly called MTBE, a chemical that is used as a fuel additive.  The clean-up and investigation of the collision closed the channel from the afternoon of March 9 until the morning of March 12.

At the time of the collision, the tanker Carla Maersk was traveling outbound in the channel transporting MTBE.  The bulk carrier Conti Perido was heading inbound with a load of steel.  Both ships were significantly damaged by the collision and three cargo tanks ruptured on the Carla Maersk, spilling the MTBE. Limited information has been released about what caused the accident, but a National Transportation Safety Board investigation is underway.  Initial reports are that both vessels were traveling at about 9 knots, which is typical for this stretch so excessive speed does not appear to be a cause.  It has also been reported that it was foggy at the time of the accident which may have played a role in the accident.

An initial Cause Map can be built using the information that is available.  The first step in the Cause Mapping process is to fill in an Outline with the basic background information along with the impacts to the goals.  Like many incidents, this collision impacted several different goals.  The safety goal was impacted because MTBE is toxic and has the potential to cause injuries.  The environmental goal was clearly impacted by the release of MTBE.  The multiple-day closure of the Houston Ship Channel is an impact to the production/schedule goal and the impact to local businesses resulting from closure is an impact to the economic goal.  The damage to the ships is an impact to the equipment goal.

On the outline, there is also a line to record the frequency of how often a similar event has occurred.  It’s important to consider the frequency because a small problem that occurs often may very well warrant a more detailed investigation than a small problem that has only been seen once.  In this example, there have been previous ship collisions.  This accident was the second ship collision to occur in the channel in a week.  Two large ships bumped on March 5, 2015, which did not result in any injuries or pollution.

Release of MTBE is a significant concern, but the impacts of this ship collision could easily have been worse.  MTBE is volatile and flammable so there could have been a fire or the ships could have been carrying something more dangerous.  It may be difficult to get the data, but it would be interesting to know how many near misses have occurred between ships traveling in the channel. The frequency that accidents are occurring needs to be considered along with the details of any individual incident when conducting an investigation. Two collisions in a week is a pretty clear indication that there is potential for more to occur in the future if nothing is changed.

Root Cause Analysis - Incident Investigation

Train Derails in West Virginia

By Kim Smiley

On February 16, 2015, a train hauling 109 tank cars of crude oil derailed in Mount Carbon, West Virginia.  It has been reported that 27 tank cars in the train derailed.  Some of the tank cars were damaged and released an unknown amount of crude oil, resulting in a large fire.  Hundreds of families in the surrounding area were evacuated, but only one injury was reported.

The accident investigation is still ongoing, but what information is known can be used to build an initial Cause Map, a visual format for performing a root cause analysis.  The Cause Map can be easily expanded as needed to document additional information as it becomes available.

The first step in the Cause Mapping process is to fill in an Outline with the basic background information for the issue as well as how the overall goals were impacted. In this example, there were many impacted goals.  The safety goal is impacted because there was an injury, the property goal is impacted because of the damage to the train, the environmental goal is impacted because of the release of oil, etc.  Once the Outline is complete, the Cause Map itself is built by starting with an impact to a goal, asking “why” questions, and laying out all the causes that contributed to an issue.

The significant aftermath of this derailment is known, but little has been released about what specifically caused the train to derail.  It was snowing heavily at the time of the accident, which may have played a role, but since more evidence is needed, a “?” is included on the Cause Map.  Data from the digital data recorder has shown that the train was not speeding at the time of the accident, which has been a factor in previous derailments.  Another fact worth noting is that the damaged train cars were a newer design that incorporated modern safety upgrades.

With so many unknowns, the Federal Railroad Administration is conducting a full-scale investigation to determine exactly what happened.  The damaged tank cars, track, and other components along with relevant maintenance and inspection records will be all be analyzed to better understand this derailment.

Unfortunately, crude oil train accidents are predicted to become increasingly common as the volume of flammable liquids being transported by rail continues to rise.  According to the Association of American Railroad, 40 times more oil was transported by rail in 2012 than in 2008. Hopefully, the lessons learned from this derailment can be used to help reduce the risk of future rail accidents.

To view the Outline and initial Cause Map for this accident, click on “Download PDF” above.

Root Cause Analysis - Incident Investigation

Early Problems with Mark 14 Torpedoes

By Kim Smiley

The problems with Mark 14 torpedoes at the start of World War II are a classic example that illustrates the important of robust testing.  The Mark 14 design included brand new, carefully guarded technology and was developed during a time of economic austerity following the Great Depression.  The desire to minimize costs and to protect the new exploder design led to such a limited test program that not a single live-fire test with a production model was done prior to deploying the Mark 14.

The Mark 14 torpedo design was a step change in torpedo technology. The new Mark VI exploder was a magnetic exploder designed to detonate under a ship where there was little to no armor and where the damage would be greatest.  The new exploder was tested using specially instrumented test torpedoes, but never a standard torpedo. Not particularly shocking given the lack of testing, the torpedoes routinely failed to function as designed once deployed.

The Mark 14 torpedoes tended to run too deep and often failed to detonate near the target. One of the problems was that the live torpedoes were heavier than the test torpedoes so they behaved differently. There were also issues with the torpedo’s depth sensor.  The pressure tap for the sensor was in the rear cone section where the measured pressure was substantially less than the hydrostatic pressure when the torpedo was traveling through the water.  This meant that the depth sensor read too shallow and resulted in the torpedo running at deeper depths than its set point.  Eventually the design of the torpedo was changed to move the depth sensor tap to the mid-body of the torpedo where the readings were more accurate.

The Mark 14 design also had issues with premature explosions.  The magnetic exploder was intended to explode near a ship without actually contacting it.  It used small changes in the magnetic field to identify the location of a target. The magnetic exploder had been designed and tested at higher latitudes and it wasn’t as accurate closer to the equator where the earth’s magnetic field is slightly different.

In desperation, many crews disabled the magnetic exploder on Mark 14 torpedoes even before official orders to do so came in July 1943.  Use of the traditional contact exploder revealed yet another design flaw in the Mark 14 torpedoes.  A significant number of torpedoes failed to explode even during a direct hit on a target.  The conventional contact exploder that was initially used on the Mark 14 torpedo had been designed for earlier, slower torpedoes.  The firing pin sometimes missed the exploder cap in the faster Mark 14 design.

The early technical issues of the Mark 14 torpedoes were eventually fixed and the torpedo went on to play a major role in World War II.  Mark 14 torpedoes were used by the US Navy for nearly 40 years despite the early issues.  But there is no doubt that it would have been far more effective and less painful to identify the technical issues during testing rather than in the field during war time.  There are times when thorough testing may seem too expensive and time consuming, but having to fix a problem later is generally much more difficult.  No one wants to waste effort on unnecessary tests, but a reasonable test program that verifies performance under realistic conditions is almost always worth the investment.

To view a high level Cause Map of the early issues of the Mark 14 torpedoes, click “Download PDF”.

You can also learn more about the torpedoes by clicking here and here.

Root Cause Analysis - Incident Investigation

Deadly Train-Car Collision

By Kim Smiley

On February 3, 2015, an SUV was struck by a commuter train near Valhalla, New York.  The driver of the vehicle and 5 train passengers were killed in the accident.  The National Transportation Safety Board (NTSB) is investigating the accident to determine what went wrong.

An initial Cause Map, a visual root cause analysis, can be built to analyze and document what is known about this train-car collision.  A Cause Map visually lays out the cause-and-effect relationships that contributed to an issue and focuses on understanding all the causes, not THE root cause.  Generally, identifying more causes results in a greater number of potential solutions being considered.

So why did the train hit a vehicle?  Eyewitnesses have stated that the SUV was hit by a crossing gate as it descended.    It is not clear why the SUV didn’t stop prior to entering the railroad crossing area. The driver pulled the SUV forward onto the tracks rather than backing up and the train struck the vehicle shortly after.  Investigators don’t know why the driver stopped on the tracks, but initial reports are that all safety features, such as the crossing gate, signs and train horn, were functioning properly at the time of the accident.

Unfortunately, it’s not unusual for passengers in a vehicle struck by a train to be injured or killed, but it is less common for fatalities among the train passengers.  Investigators are working to determine what made this accident particularly dangerous for train passengers.  The NTSB plans to use information about the passengers’ injuries and a diagram of where people were sitting on the train to try to understand what happened during the collision.  Post-accident photos of the train show that significant fire damage occurred, likely fueled by the gas in the SUV.

One of the open questions is whether the electrified third rail contributed to the accident and subsequent injuries. Metro-North uses an unusual “under-running” third rail design where power is taken from the bottom of the rail.  During the collision, 400 feet of the third rail broke apart and 12 pieces pierced both the SUV and the train. This rail design uses a metal shoe that slips underneath the third rail and some think that the force of the collision may have essentially pried up the rail and threw it into the train and vehicle.

Open questions can be documented on the initial Cause Map with a question mark.  As more information becomes available, the Cause Map can quickly be updated.  Typically, Cause Maps are built in Excel and different versions can be saved as different sheets to document the investigation process.

Click on “Download PDF” above to view an initial Cause Map of this accident, built from the information in the media articles on the accident.

Root Cause Analysis - Incident Investigation

TransAsia Plane Crashes into River in Taiwan

By Kim Smiley

On February 4, 2015, there were 53 passengers onboard TransAsia Airways Flight 235 when the plane crashed into the Keelung River shortly after taking off from the Taipei Shonshan Airport.  There were 15 survivors from this dramatic crash where the plane hit a bridge and taxi cab prior to turning upside down before hitting the river. (The crash was caught on video by dash cameras from a vehicle on the bridge and can be seen here.)

Investigators are still working to determine exactly what happened, but some early findings have been released.  The plane involved in this crash was a turboprop with two engines.  This model of plane can fly safely with only one engine, but both engines had issues immediately prior to the crash so the pilots were unable to control the plane.

Data from the flight recorder shows that the right engine idled 37 seconds after takeoff.  No details about what caused the problem with the right engine have been made available.  The initial investigation findings are that the left engine was likely manually shut down by the pilots.  It’s not clear why the functioning engine would have been intentionally shut down. Early speculation is that it was a mistake and that the pilots were attempting to restart the idled right engine when they hit the switch for the operating left engine.

The investigation into the crash is ongoing and the final report isn’t expected to be released for about a year, but based on the initial findings, a few solutions to help reduce the likelihood of future crashes have already been implemented.  TransAsia has grounded most of its turboprop aircraft pending additional pilot instruction and requalification because it is believed that pilot action may well have contributed to the deadly accident.  More than 100 domestic flights have been canceled as a result.  Additionally, Taiwan’s Civil Aeronautic Administration has announced that the carrier will be banned from adding new international routes for 12 months.  A previous crash in July 2014 had already tarnished TransAsia’s reputation and this latest disaster will certainly be scrutinized by the authorities.

An initial Cause Map, a visual root cause analysis, can be built to analyze the information that is available on this crash and to document where there are still open questions.  To view a Cause Map and Outline of this incident, click on “Download PDF” above.

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

Prison Bus Collides With Freight Train

By Kim Smiley

On the morning of January 14, 2015, a prison bus went off an overpass and collided with a moving freight train.  Ten were killed and five more injured.  Investigators believe the accident was weather-related.

This tragic accident can be analyzed by building a Cause Map, a visual root cause analysis.  A Cause Map visually lays out the cause-and-effect relationships to show all the causes (not just a single root cause) that contributed to an accident.  The first step in the Cause Mapping method is to determine how the incident impacted the overall organizational goals.  Typically, more than one goal needs to be considered.  Clearly the safety goal was impacted because of the deaths and injuries.  The property goal is impacted because of the damage to both the bus and train (two train cars carrying UPS packages were damaged).  The schedule goal is impacted because of the delays in the train schedule and the impact on vehicle traffic.

The Cause Map itself is built by starting at one of the impacted goals and asking “why” questions. So why were there fatalities and injuries?  This occurred because there were 15 people on a bus and the bus collided with a train.  The bus was traveling between two prison facilities and drove over an overpass.  While on the overpass, the bus hit a patch of ice and slid off the road, falling onto a moving freight train that was passing under the roadway.  No one onboard the train was injured and the train did not derail, but it was significantly damaged.  The bus was severely damaged.

The prisoners onboard the bus were not wearing seat belts, as is typical on many buses.  They were also handcuffed together, although it’s difficult to say how much this contributed to the injuries and fatalities.

Useful solutions to prevent these types of accidents can be tricky.  The prison system may want to review how they evaluate road conditions prior to transporting prisoners.  This accident occurred early in the morning and waiting until later in the day when temperatures had increased may have reduced the risk of a bus accident.  Transportation officials may also want to look at how roads, especially overpasses, are treated in freezing weather to see if additional efforts are warranted.

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

You can also read our previous blogs to learn more about other train collisions:

Freight Trains Collide Head-on in Arkansas

Freight Train Carrying Crude Oil Explodes After Colliding with Another

“Ghost Train” Causes Head-on Collision in Chicago

Deadly Train Collision in Poland

Root Cause Analysis - Incident Investigation

Passengers trapped in smoke-filled metro train

By Kim Smiley

A standard commute quickly turned into a terrifying ordeal for passengers on a metro train in Washington, DC the afternoon of January 12, 2015.  Shortly after leaving a station, the train abruptly stopped and then quickly filled with thick smoke. One passenger died as a result of the incident and 84 more were treated for injuries, predominantly smoke inhalation.

This incident can be analyzed by building a Cause Map, a visual root cause analysis.  A Cause Map visually lays out the cause-and-effect relationships to show all the causes that contributed to an issue.  The first step in the Cause Mapping process is to define the problem by filling in an Outline with the basic background information as well as documenting how the issue impacts the overall goals.  For this example, the safety goal is clearly impacted by the passenger death and injuries.  A number of other goals should also be considered such as the schedule goal which was impacted by significant metro delays.  (To view an Outline and initial Cause Map for this issue, click on “Download PDF” above.)

So why were passengers injured and killed?  Passengers were trapped on the train and it filled with smoke.  It is unclear why the train wasn’t able to back up to the nearby station once the smoke formed and investigators are working to learn more.  (Open issues can be documented on the Cause Map with a question mark to indicate that more evidence is needed.)  There are also questions about the time emergency workers took to reach the train to aid in evacuation of passengers so this is another area that will require more information to fully understand. By some account, it took 40 minutes for firefighters to reach the trapped passengers.

Initial reports are that smoke was caused by an electrical arcing event, likely from the cables supporting the high voltage third rail used to power the trains. The specifics of what caused the arc are being investigated by the National Transportation Safety Board and will be released when the investigation is concluded.  What is known is that there was significant smoke caused by the arc, but no fire.  There have also been reports of water near the rails that may have been a factor in the arcing.

Eyewitness accounts of this incident are horrifying.  People had little information and didn’t know whether there was fire nearby at first.  They were told to remain on the train and await rescue, but the rescue took some time, which surely felt longer to the scared passengers.  It won’t be clear what solutions need to be implemented to prevent similar problems in the future until the investigation is complete, but I think we can agree that metro officials need to work to ensure passenger safety going forward.