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

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.”

IfA technical or engineering control existsThe control relies on a human reviewer or operatorThe control involves a transfer of responsibility. For example, a document reviewed by both manufacturing and quality.
ExamplesSeparation among manufacturing or packaging lines


Emergency power supply

Dedicated equipment


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.

7 thoughts on “Barriers and root cause analysis

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.