Barriers and root cause analysis

Barriers, or controls, are one of the (not-at-all) secret sauces of root cause analysis.

By understanding barriers, we can understand both why a problem happened and how it can be prevented in the future. An evaluation of current process controls as part of root cause analysis can help determine whether all the current barriers pertaining to the problem you are investigating were present and effective (even if they worked or not).

At its simplest it is just a three-part brainstorm:

Barrier Analysis
Barriers that failed	The barrier was in place and operational at the time of the accident, but it failed to prevent the accident.
Barriers that were not used	The barrier was available, but workers chose not to use it.
Barriers that did not exist	The barrier did not exist at the time of the event. A source of potential corrective and preventive actions (depending on what they are)

The key to this brainstorming session is to try to find all of the failed, unused, or nonexistent barriers. Do not be concerned if you are not certain which category they belong in.

Most forms of barrier analysis look at two types, technical and administrative, and we can further breakdown administrative into “human” and “organization.”

Choose	Technical	Human	Organization
If	A technical or engineering control exists	The control relies on a human reviewer or operator	The control involves a transfer of responsibility. For example, a document reviewed by both manufacturing and quality.
Examples	Separation among manufacturing or packaging lines   Emergency power supply Dedicated equipment Barcoding Keypad controlled doors Separated storage for components Software that prevents a workflow from going further if a field is not completed Redundant designs	Training and certifications   Use of checklist Verification of critical task by a second person	Clear procedures and policies   Adequate supervision Adequate load of work Periodic process audits

These barriers are the same as current controls is in a risk assessment, which is key in a wide variety of risk assessment tools.