Uncategorized

March 27, 1977: Two Jets Collide on Runway, Killing 583

By ThinkReliability Staff

March 27, 1977 was a difficult day for the aviation industry.  Just after noon, a bomb exploded at the Las Palmas passenger terminal in the Canary Islands.  Five large passenger planes were diverted to the Tenerife-Norte Los Rodeos Airport, where they completely covered the taxiway of the one-runway regional airport.  Less than five hours later, when the planes were finally given permission to takeoff, two collided on the runway, killing 583, making this the worst accident at the time (and second now only to the September 11, 2001 attacks in the US.)

With the benefit of nearly 40 years of hindsight, it is possible to review the causes of the accident, as well as look at the solutions implemented after this accident, which are still being used in the aviation industry today.  First we look at the impact to the goals as a result of this tragedy.  The deaths of 583 people (out of a total of 644 on both planes) are an impact to the safety goal.  The compensation to families of the victims (paid by the operating company of one of the planes) is an impact to the customer service goal.  The property goal was impacted due to the destruction of both the planes, and the labor goal was impacted by the rescue, response, and investigation costs that resulted from the accident.

Beginning with one of the impacted goals, we can ask why questions to diagram the cause-and-effect relationships related to the incident.  The deaths of the 583 people onboard were due to the runway collision of two planes.  The collision occurred when one plane was taking off on the runway, and the other was taxiing to takeoff position on the same runway (called backtracking).

Backtracking is not common (most airports have separate runways and taxiways), but was necessary in this case because the taxiway was unavailable for taxiing.  The taxiway was blocked by the three other large planes parked at the airport.  A total of five planes were diverted to Tenerife which, having only one runway and a parallel taxiway, was not built to accommodate this number of planes.  There were four turnoffs from the runway to the taxiway; the taxiing plane had been instructed to turn off at the third turn (the first turn that was not blocked by other planes).  For unknown reasons, it did not, and the collision resulted between the third and fourth turnoff.  (Experts disagree on whether the plane would have been able to successfully make the sharp turn at the third turnoff.)

One plane was attempting takeoff, when it ran into the second plane on the runway.  The plane  taking  off was unaware of the presence of the taxiing plane.  There was no ground radar and the airport was under heavy fog cover, so the control tower was relying on positions reported by radio.  At the time the taxiing plane reported its position, the first plane was discussing takeoff plans with the control tower, resulting in interference rendering most of the conversation inaudible.  The pilot of the plane taking off believed he had clearance, due to confusing communication between the plane and the air traffic control tower.  Not only did the flight crews and control tower speak different languages, the word “takeoff” was used during a conversation that was not intended to provide clearance for takeoff.  Based on discussions between the pilot and flight crew on the plane taking off have, investigators believed, but were not able to definitively determine, that other crew members may have questioned the clearance for takeoff, but not to the extent that the pilot asked the control tower for clarification or delayed the takeoff.

After the tragedy, the airport was upgraded to include ground radar.  Solutions that impacted the entire aviation industry included the use of English as the official control language (to be used when communicating between aircraft and control towers) and also prohibited the use of the word “takeoff” unless approving or revoking takeoff clearance.  The potential that action by one of the other crew members could have saved the flights aided in the concept of Crew Resource Management, to ensure that all flight crew members could and would speak up when they had questions related to the safety of the plane.

Though this is by far the runway collision with the greatest impact to human life, runway collisions are still a concern.  In 2011, an Airbus A380 clipped the wing of a Bombardier CRJ (see our previous blog).  Officials at Los Angeles International Airport (LAX) experienced 21 runway incursions in 2007, after which they redesigned the runways and taxiways so that they wouldn’t intersect, and installed radar-equipped warning lights to provide planes with a visual warning of potential collisions (see our previous blog).

To view the outline, Cause Map and recommended solutions from the Tenerife runway collision of 1977, click on “Download PDF” above.  Or, click here to read more.

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

Plane Narrowly Avoids Rolling into Bay

By ThinkReliability Staff

Passengers landing at LaGuardia airport in New York amidst a heavy snowfall on March 5, 2015, were stunned (and 23 suffered minor injuries) when their plane overran the runway and approached Flushing Bay.  The National Transportation Safety Board (NTSB) is currently investigating the accident to determine not only what went wrong in this particular case, but what standards can be implemented to reduce the risk of runway overruns in the future.

Says Steven Wallace, the former director of the FAA’s accident investigations office (2000-2008), “Runway overruns are the accident that never goes away.  There has been a huge emphasis on runway safety and different improvements, but landing too long and too fast can result in an overrun.”  Runway overruns are the most frequent type of accident (there are about 30 runway overruns due to wet or icy runways across the globe every year), and runway overruns are the primary cause of major damage to airliners.

Currently, the NTSB is collecting data (evidence) to aid in its investigation of the accident.  The plane is being physically examined, and the crew is being interviewed.  The data recorders on the flight are being downloaded and analyzed.  While little information is able to be verified or ruled out at this point, there is still value in organizing the questions related to the investigation in a logical way.

We can do this using the Cause Mapping method of root cause analysis, which organizes cause-and-effect relationships related to an incident.  We begin by capturing the impact to an organization’s goals.  In this case, 23 minor passenger injuries were reported, an impact to the safety goal.  There was a fuel leak of unknown quantity, which impacts the environmental goal.  Customer service was impacted due to a scary landing and evacuation from the aircraft via slides.  Air traffic at LaGuardia was shut down for 3 hours, impacting the production goal.  Both the airplane and the airport perimeter fence suffered major damage, which impacts the property/equipment goal.  The labor goal was also impacted due to the response and ongoing investigation.

By beginning with an impacted goal and asking “why” questions, we can begin to diagram the potential causes that may have resulted in an incident.  Potential causes are causes without evidence.  If evidence is obtained that supports a cause, it becomes a cause and it is no longer followed by a question mark.  If evidence rules out a cause, it can be crossed out but left on the Cause Map.  This reduces uncertainty as to whether a potential cause has been considered and ruled out, or not considered at all.

In this case, the NTSB will be looking into runway conditions, landing procedures, and the condition of the plane.   According to the airport, the runway was cleared within a few minutes of the plane landing, although the crew has said it appeared all white during landing.  The National Weather Service reported 7″ of snow in the New York area on the day of the overrun.  Procedures for closing runways or aborting landings are also being considered.  Just prior to the landing, other pilots who had recently landed reported braking conditions as good.

The crew has also reported that although the auto brakes were set to max, they did not feel any deceleration. The entire braking system will be investigated to determine if equipment failure was involved in the accident.  (Previous overruns have been due to brake system failures or the failure of reverse thrust from one of the engines, causing the plane to veer.)  The pilot also reported the automatic spoiler did not deploy, but they were deployed manually.

Also being investigated are the landing speed and position, though there is no evidence to suggest that there was any issue with crew performance.  As more information is released, it can be added to the investigation.  When the cause-and-effect relationships are better determined, the NTSB can begin looking at recommendations to reduce future runway overruns.

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.

Uncategorized

Working Conditions Raise Concerns at Fukushima Daiichi

By ThinkReliability Staff

The nearly 7,000 workers toiling to decommission the reactors at Fukushima Daiichi after they were destroyed by the earthquake and tsunami on March 11, 2011 face a daunting task (described in our previous blog). Recent events have led to questions about the working conditions and safety of these workers.

On January 16, 2015, the local labor bureau instructed the utility that owns the plants to reduce industrial accidents. (The site experienced 23 accidents in fiscal year 2013 and 55 so far this fiscal year.) Three days later, on January 19, a worker fell into a water storage tank and was taken to the hospital. He died the next day, as did a worker at Fukushima Daini when his head got caught in machinery. (Fukushima Daini is nearby and was less impacted by the 2011 event. It is now being used as a staging site for the decommissioning work at Fukushima Daiichi.)

Although looking at all industrial accidents will provide the most effective solutions, often digging into just one in greater detail will provide a starting point for site improvements. In this case, we will look at the January 19 fall at Fukushima Daiichi to identify some of the challenges facing the site that may be leading to worker injuries and fatalities.

A Cause Map, or visual form of root cause analysis, is begun by determining the organizational impacts as a result of an incident. In this case the worker fall impacted the safety goal due to the death of the worker. The environmental goal was not impacted. (Although the radiation levels at the site still require extensive personal protective equipment, the incident was not radiation-related.) Workers on site have noted difficult working conditions, which are thought to be at least partially responsible for the rise in incidents, as are the huge number of workers at the site (itself an impact to the labor/time goal). Lastly, local organizations have raised regulatory concerns due to the high number of incidents at the site.

An analysis of the issues begins with one impacted goal. In this case, the worker death resulted from a fall into a ten-meter empty tank. The worker was apparently not found immediately (though specific timeline details and whether or not that impacted the worker’s outcome have not been released) because it appears he was working alone, likely due to the massive manpower needs at the site. Additionally, the face masks worn by all workers (due to the high radiation levels still present) limit visibility.

The worker was checking for leaks at the top of the tank, which is being used to store water used to cool the reactors at the site. There is a general concern about lack of knowledge of workers (many of whom have been hired recently with little or no experience doing the types of tasks they are now performing), though again, it’s unclear whether this was applicable in this case. Of more concern is the ineffective safety equipment – apparently the worker did not securely fasten his safety harness.

The reasons for this, and the worker falling in the first place, are likely due to worker fatigue or lack of concentration. Workers at the site face difficult conditions doing difficult work all day (or night) long, and have to travel far afterwards, as the surrounding area is still evacuated. Reports of mental health issues and fatigue in these workers has led to the opening of a new site providing meals and rest for these workers.

These factors are likely contributing to the increase in accidents, as is the number of workers at the site, which doubled from December 2013 to December 2014. Local organizations are still calling for action to reduce these actions. “It’s not just the number of accidents that has been on the rise. It’s the serious cases, including deaths and serious injuries that have risen, so we asked Tokyo Electric to improve the situation,” says Katsuyoshi Ito, a local labor standards inspector.

In addition to improving working conditions, the site is implementing improved worker training – and looking at discharging wastewater instead of storing it, which would reduce the pieces of equipment required to be monitored and maintained. Improvements must be made, because decades of work remains before work at the site will be completed.

Click here to sign up for our FREE webinar “Root Cause Analysis Case Study: Fukushima Daiichi” at 2:00 pm EDT on March 12 to learn more about how the earthquake and tsunami on March 11, 2011 impacted the plant.

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