What's Wrong With Having a Blocked Column?

What is blocked work?
Generally speaking, blocked work is an item the team has started where progress is stopped and unable to proceed for a determined or undetermined amount of time. More specifically, the team should define when they consider something as blocked so that when it happens they know how to handle it, generally this is based on a decided upon minimum time limit of when a work cannot make progress.

Count blocked work against work in progress (WIP) limits

In Kanban, we follow the practice of actively managing your workflow. Ways of doing this include managing Work in Progress (WIP) limits, not letting items age unnecessarily, avoiding work items piling up, and unblocking blocked work. In order to actively manage items in a workflow, blocked items should count against work in progress limits and the team should actively work on unblocking blocked work. 

Having a blocked column is an anti-pattern 

Blocked columns:

• Risk the team pulling in more items and breaking the work in progress (WIP) limit
• Do not visualize what column an item is blocked in.
• Items are not likely to get the attention needed to get unblocked.

Use Visual Cues to identify blocked work

An alternative approach is to use a visual cue for the block and keep the item in the column where the work is blocked. This method ensures the team actively manages to unblock the work and continues to count against work in progress WIP limits. In addition, it will be easier to resume work once the item becomes unblocked as WIP limits have not been violated.

As with many practices, you may find an example that needs an exception.
Having explicit policies around how to handle blocked items can prepare your team to handle such situations. 

Want to learn more about how to handle blocked work?
Check out Drunk Agile, Episode 65 - Blocker Policies
and then check out Episode 68 Blockers Outside the Team’s Control