Is Takt Really Magic?

By: Kevin Rice

Something I asked my self as I started researching Takt and its benefits. Like you; I am newer to Takt planning and thought I would take a concept that intrigued me and start to explore my findings.

 

Scheduling with Takt allows you to take a project with a linear schedule and implement strategic overlapping. This leads to shorter project duration and more buffer time, but how is this possible?

Today I’d like to dive deeper into Little’s “Takt” Law, also called Dlouhy & Binninger’s Law. This law describes the relationship between inputs in a Takt plan. It goes something like this:

(Takt Wagons + Takt Zones – 1) x Takt Time = Total Duration

(TW + TZ – 1) x TT = TD

I’m sure that most of you are familiar with this idea, but I wanted to dive into the math and really understand how this works, so I turned to one of my best friends, Excel. Yeah, I’m weird like that.

I started by building a simple matrix that showed a few of the possible Takt plans for a given set of inputs and the actual Takt flow diagram for each one. It looked like this:

Once I built the matrix I found I had more questions than I did when I started. Questions like:

• What is the “best” Takt plan for this set of inputs?

• Why does each trade get 2 extra days when going from 2 sequences to 4 sequences? And why do they get 6 extra days when going to 8 sequences?

• What about other numbers of sequences?

To answer these questions I turned back to my friend Excel and graphed out what the theoretical lower limit for this set of inputs ranging from 1 and 10 sequences.

 

 

This shows the Law of Diminishing Returns when Takt planning. This graph is great, but it is theoretical and I wanted to see what happens when you take it to the real world. We don’t often work in half day increments and it is common to round these up to the nearest day or week. Adding this real life constraint of rounding each Takt time up to the nearest unit changes things significantly. So back to excel I went and here is what happens.

 

 

Crazy stuff right! Rounding changes everything! You can see how important it is to know some of this information up front during the planning phases of your project. Understanding how it affects duration is critically important to formulate the best Takt plan. Notice that the theoretical lower limit intersects with certain numbers of sequences or zones. These Takt plans will be lean and mean, but not always possible, or desired. Sometimes a certain number of sequences or zones is better for a particular project, but it is important to know how this affects the Takt plan relative to possibilities. This way a more informed decision can be made to balance all of the factors involved in completing large scale projects.

Rounding is also where the extra 2 days and 6 days of trade work come from. Rounding each Takt time up accrues over the project. This gives each trade more time on the project and still reduces the overall project duration. It became obvious that the utility of a tool that would model all the different possible Takt plans for any given set of inputs would really help to optimize Takt planning and allow for a more efficient and strategic overall plan.