- You've seen that one of the key parts in Kanban
is limiting the work in progress.
Some teams use the acronym WIP, for work in progress.
You might even hear a team say
we need to adjust our WIP limit.
The WIP limit is the number of Kanban cards
that you can have in any one column.
When you assign your development column a WIP limit of five,
that means that the team should work
on no more than five work items at one time.
Think of the Kanban card as the demand on the team.
The organization is trying to pull work through the team.
The columns place a limit
on how much work the organization can demand.
Demand is a tricky thing to figure out.
If your organization had a consistent demand,
then there wouldn't be any reason for WIP limits.
Your team could always work on a steady stream of work.
Unfortunately, this is rarely the case.
Think of it this way.
Imagine you wanted to regulate the amount of traffic
that was going over a bridge.
It could be pretty straightforward to set up booths
at both sides of the bridge to limit the amount of vehicles.
They could even use a Kanban system.
Each vehicle would get a card
as they passed through the booth.
Then, they could drop the card off at the opposite booth
as they left the bridge.
This system would make sure
that there are only a certain number of vehicles
on the bridge at one time.
But you might notice that there's a flaw in this system.
If you limit the number of vehicles,
you're not necessarily limiting the demand on the bridge.
Think about if you had 50 Kanban cards for each vehicle,
but there's no restriction on the size of the vehicle.
You could have 50 trucks or you could have 50 motorcycles.
Each of these would have
a vastly different demand on the bridge.
That's why it's very important for teams
to do something called demand analysis.
This is when you predict the amount of work
your organization demands from the team.
Some organizations have a lot of work
at the very beginning of your project.
Other organizations might get a big bunch of change requests
during certain months of the year.
Your teams has to try and predict these demands,
so that they can make sure that they have enough capacity
to deal with the work.
Once you've figured out the demand on the team,
there's a couple of tricks you could try
to display your work on the board.
You could try to split the board horizontally,
and have two different capacity measures
on each side of the column.
In a sense it would be like creating an extra toll booth
on each side of the bridge.
There would be one for cars and one for trucks.
You could have the toll booths
give out 10 Kanban cards for trucks and 40 for cars.
You could also try to create
different color coding for your Kanban cards.
Maybe you'd have a green card
that would show a higher demand.
It might count as two Kanban cards
when you look at your WIP limit.
This would be almost like if you had 40 yellow cards
and 10 green cards for your bridge.
Then, you instruct the toll booths to only allow
trucks on the bridge when there's an available green card.
Either of these techniques work fine,
but don't spend too much time designing the board.
Instead, put most of your energy into trying to predict
the work demands on your team.