By ThinkReliability Staff

At approximately 11:00 p.m. on October 12th, 2009, the two 500,000 lb strength towlines connecting La Prinsesa barge to its tug broke free.  The tug was unable to recapture the ship, and it drifted for about seven hours in heavy seas caused by a wind-driven rain storm before grounding at Sandbridge Beach in Virginia, just shy of the Sandbridge pier.

So far the 84 hazardous material (HAZMAT) loads the barge was carrying appear to be intact.   There were no injuries, as the barge was unmanned.  Damage to the ship is not known at this time.   However, the incident had the potential to cause injuries, a HAZMAT spill that could have led to an evacuation, and far more damage to the ship and the beach.  The incident did lead to the loss of the towlines, which are valued at approximately $70,000 and a delay in the barge’s arrival.

It’s unclear what caused the towlines to break free.  Initial solutions are to clear the area and ballast the tug to attempt to keep it from drifting.  On November 17, the barge began being towed to open waters where the cargo can be off-loaded safely. However, long-term solutions that would prevent another incident of this type will only be determined after the causes of the issue are determined.

Click on “Download PDF” to view a PDF showing the root cause analysis investigation based on what is known  so far.  A thorough root cause analysis built as a Cause Map can capture all of the causes in a simple, intuitive format that fits on one page.  Even more detail can be added to the Cause Map as the analysis continues. As with any investigation the level of detail in the analysis is based on the magnitude of the impacts (or potential impacts).

By ThinkReliability Staff

The first step of the Cause Mapping strategy of root cause analysis is to define the problem with respect to the organization’s goals.  In order to do this, you need to know what an organization’s goals are.  While we provide Cause Mapping root cause analysis templates that will give you an idea of where to start, your organization may wish to personalize their investigations so that they correspond to your particular goals.

To define your organization’s goals, try to imagine a perfect day for your organization.  No matter what industry you’re in, that perfect day doesn’t include anyone getting hurt or killed.  This is the safety goal.  However, if your organization regularly is responsible for the health and welfare of people other than your employees, you may wish to have more than one category of safety.  For example, a hospital may have both “patient safety” and “employee safety” goals.  A public school may have “student safety” and “employee safety” goals.

Another goal generally common to all industries is the goal of not impacting the environment.   However, some industries have a base level of environmental impact, so their goal might be to not surpass that level rather than having no impact.  Environmental impacts usually result from leaks or spills of any material other than water, but may also result from improper storage or disposal of hazardous material.

Some organizations may have as a goal to meet regulatory requirements.  If an organization has an OSHA (Occupational Safety and Health Administration) reportable injury, this is an impact to the “Regulatory Compliance” goal.  Organizations may also have a “Compliance” goal if they are subject to another governing body, such as a trade group or an external accreditation.

Organizations usually exist to provide either products, services, or both.  If an organization provides products, a goal of that organization may be to get a set amount of products produced and delivered on a certain schedule.  We call this the “Production/Schedule” goal.  An organization that provides services wants to ensure that its customers are satisfied with the services they provide.  This is the “customer service” goal.  Many organizations will use both goals to define a problem.

Another area of concern for almost all organizations is cost.  An incident that requires additional labor, rework, or lost product results in unplanned costs for the organization.  We call this goal the “material and labor goal”.  If an incident results in many costs, it’s possible to itemize them within the problem outline.  Quantifying all the costs associated with an incident can help prioritize which incidents require the most immediate attention.  It also provides a bound for the cost of solutions – installing a $100,000 machine to solve an infrequent $20,000 problem doesn’t make sense.  (Of course, for incidents that involve impacts that can’t be easily quantified – human safety, regulatory requirements, customer service, etc.  – these impacts must be considered above and beyond the “cost” of the incident.)

Once you’ve determined all of the goals that are meaningful to your organization, you’re ready to make an outline for the first step of the Cause Mapping method of root cause analysis – define the problem.  But what order do you put the goals in?  Generally, the goals go in order from most to least important.  The safety goal is almost always at the top.  Your organization’s mission statement is an excellent resource to determine the order of the goals.  Ideally, they’ll follow along with your mission statement, with any goals not specifically called out (such as the “material and labor” goal) listed below.  It’s also possible to use a different order so that the biggest impacts from an incident are listed at the top.  However, your organization may prefer to always use the same order for consistency.

If an incident resulted in no impact to one of your organization’s goals, don’t delete the goal from the problem outline.  Instead, write “N/A” next to the goal.  That way, it’s clear that the goal was considered but it was determined that there was no impact.  Deleting the goal may lead others to believe that it’s no longer a goal of the organization!

Check out our examples to see a problem definition in action!

ThinkReliability has specialists who can solve all types of problems. We investigate errors, defects, failures, losses, outages and incidents in a wide variety of industries.  Contact us for investigation services and root cause analysis training.

By ThinkReliability Staff

In a previous blog, I wrote about the impressively quick repairs to the San Francisco-Oakland Bay Bridge.  These repairs allowed the heavily-traveled bridge to reopen only an hour and a half late from scheduled repairs, despite unexpectedly finding a cracked eyebar during that time.

However, during evening rush hour on October 27, less than 2 months after the eyebar repair had been completed, two metal rods and a 5,000 pound metal beam fell onto the roadway.  The items that fell were part of the previous repair, which was supposed to have lasted until the new bridge opened in 2013. Although only one motorist was injured, other injuries or even fatalities were possible, and the damage to the bridge necessitated repairs and closing the transportation route for 280,000 cars a day for more than 5 days.

The “cause” given for the failure of one of the rods (which snapped, leading to the falling of the other rod and the beam) was fatigue caused by high (over 30 mile per hour) winds.  However, an adequate repair would have been able to withstand less than 2 months of traffic and 30 mile per hour winds, so the rod failure must have been caused by the combination of the high winds and an inadequate repair.

Given the speed with which the repair was completed (see our previous blog), it’s possible that the repair job was rushed.  Additionally, the Federal Highway Administration did not inspect the bridge after the repairs were completed, instead relying on state inspection reports.  Had another agency inspected the repairs, it’s possible the problems with the repair would have been noticed and fixed before the bridge was re-opened.

A summary of the investigation to date can be found on the downloadable PDF.  (To open, click on “Download PDF” above.)  The investigation includes a timeline, which can aid in the understanding of this issue, the problem outline, and the Cause Map (visual root cause analysis).  A thorough root cause analysis built as a Cause Map can capture all of the causes in a simple, intuitive format that fits on one page.  As with any investigation, as more information becomes known, more detail can be added to the Cause Map.