Card Wall is not Kanban

Ever been in a meeting or discussing a project when someone has said...?

What we need is a Kanban board!

I often see project teams standing at whiteboards covered in sticky-notes, deep in stand-up meetings, discussing this or that feature. They have columns for in progress, backlog, live or similar, and more. Work gets done; stickies get moved; everyone high-fives and says:

Hey man we’re doing Kanban!

But they’re not. And here’s why: a card wall is not Kanban.

That’s not to say a card wall isn’t an incredibly useful collaboration tool. Any physical information radiator is a good thing and a card wall is a great way to visualize work in progress. It’s a useful focus for stand-up meetings and can be helpful in planning and prioritization, However, in order to be Kanban, it must be a pull system.

A pull system is one where the flow of work is determined by the availability of upstream resources. This is in contrast to the more familiar model of a push system, where a piece is worked on regardless of whether the upstream process is ready to receive it.

The failure of push systems is that they often create large inventories of work in progress (WIP), which in Lean are considered waste. Pull systems solve this problem by using strict WIP limits (i.e. a maximum number of tickets) for each process (i.e. each column on the card wall). Once a WIP limit has been reached, no new piece of work can enter that process, even if the resources for that process are available. WIP is only cleared when a ticket is pulled into the next upstream process. This has the additional advantage of creating slack (a period of time when a resource is un-utilized), but that’s a whole other conversation.

In most process chains - the development process being a fine example - a pull system can only be achieved using WIP limits. Without WIP limits, you almost certainly have a push system. And if you have a push system, you’re not doing Kanban.

So how do you convert your card wall to Kanban? Actually, you may decide you don’t want to. If you have a small multi-disciplined team working efficiently and you have a good flow of work, then it may not make a great deal of difference whether it’s pull or push. But let’s say you do:

  1. Firstly, identify WIP limits for each column on your board. There are lots of techniques for calculating WIP limits, but an intuitive guess is as good as any initially. Simply write a sensible number at the top of each column.
  2. Secondly, never allow there to be more tickets in a column than the number written at the top.
  3. Thirdly, evolve. Kanban comes from the same place as Kaizen (continuous improvement) and you should constantly test and improve your Kanban to maximize the process flow.

We’ve barely scratched the surface of how to do Kanban here, but it's a good start. If you want to know more about implementing Kanban as a fully-fledged process management system, then contact me.

I also recommend the following works on Kanban and Lean: