In Takt planning, there are currently no tools on the market that give you a process for identifying and leveling production. Just because you can create a pretty chart does not mean that you can make that happen in the field. If construction were that simple, this topic would not be worth writing about. The truth is that construction production is very complex, one of the most complex systems for various reasons. This is why Excel is so powerful when takt planning and, as a rule of thumb, I suggest all Superintendents, Site Managers, Construction Managers, Planners, or Schedulers use Excel when starting Takt Planning.
There are a number of ways to adjust the dials to level the work to achieve that steady takt time duration of each step or Takt Wagon in the process. These might include:
- Takt Zone Adjustments
- Takt Time Adjustments
- Work Packaging
- Crew Sizing
- New Methods, Tools & Equipment
Think of each task in the train (or sequence), with no leveling or work packaging. There is probably a difference of duration of each activity as shown here:
The top of the image shows the duration of work that each task or group of tasks would need in order to complete the work. Now let us say you have identified four zones on your project where this same sequence of work would be the same. This is what that might look like:
One thing you notice is that there is a gap that is increasing between tasks B and C. This is due to the sequence bottleneck that has a duration of 9 days. This is why C cannot start sooner. Because the crew would be working from one area to the next and thus going at a slower rate than the other trades. I named this the inefficiency gap. I discovered this phenomenon while managing a $100 Million Dollar Renovation Project. Here is the very chart in which I discover the inefficiency gap back in 2017:
This is what led me to looking for a better way and ultimately to Takt Planning. Now if we were to level the durations of 9 by one of the methods listed above; here is what would happen:
There is now a new bottleneck; task A now has the longest duration and thus would be dictating the flow of work. This phenomenon is identified and discussed very well in the book “The Goal” by Eli Goldratt where he describes this as the Theory of Constraints (TOC). The idea with leveling is to adjust the dials we have to achieve the ideal point where all trades and crews are moving at the same rate the same distance apart.
Now if we take some of the ways to level production and apply them throughout this sequence, we may achieve something like this:
Now we have a sequence of work that is leveled, But this begs the question: why level the production at all? To showcase this I am going to give you one more example with crew sizes. Here is how this works.
Usually, sequential construction activities are looked at as things that just have to happen as the subcontractor or Trade Partner imagines it should be done or how they think it ought to be staffed. This is usually due to the GC not providing clarity around this subject. This produces an uneven balance of work. This non-level production sequence takes longer simply because the work was not leveled as a requirement. This is why resource leveling in CPM yields poor results as the majority of projects fail to use it.
This next graphic of non-leveled sequential construction production shows that with different levels of manpower each activity has a different amount of time. Observe the Drywall, Paint, and Flooring time frames vs. the manpower they were planned with by the trade contractor.
Now during a planning session, if we were to discuss an adjustment of a few simple things, and the trades agree that this is possible this will make the work level in nature, as the next image shows. Observe the time for each as they look level, but the adjustment came from the crew size. This is one of the ways how rhythm and Takt time can be achieved and managed in construction.
Remember leveling production by adjusting the crew size is not always the answer. This is one of the methods we can use to level the production, and it’s worth noting that there are various considerations that should be taken into account before assuming this will work for your project, such as the labor market, geographical zone size, qualified manpower, scope to be executed, and more. So, of course, there is more than just the math to figure out what the plan should be.
However, when we ultimately are able to level the production, the effects are vast. It dramatically impacts the work flow and efficiency of the workers and project. Take the next image, for example. A-C are activities in your production sequence, and when scheduled are found to have different durations for each task. This produces a schedule of 28 days in total. When the work is leveled by adjusting manpower, the schedule is improved to 11 days total. That is more than 60% improvement on this section of the schedule.
I find more often than not that the answer is to have less manpower because of the shorter duration activities. These faster scopes of work are usually the problem. Yes, the trades that can go fastest are usually the biggest problem. This is where I make the argument that if we look at smaller crews (less manpower) we usually can finish sooner. I didn’t say faster, I did say sooner. The overall duration of our projects can decrease if we are willing to level the work by decreasing labor in cases.
Look at this image here of each trade going their own rate of installation. Most construction projects I see in the industry are ran like this. “I can’t bring in the next guy cause he will run out of work”:
You will notice that the contrast between the slowest and fastest colors cause the inefficiency gaping. So, if we were to slow some of them down by smaller crew sizes and use a number of leveling techniques what would be the outcome?
It is a 40% reduction of the overall duration with just leveling alone, not to mention the ability to reduce time by smaller batch sizes or other Takt principles. This is the power of Takt Planning.
While there are a number of dials and knobs to adjust in the plan to level the production, advanced Takt practitioners invest a lot of their time leveling and work packing with the trades. If we can get this right and continue to refine it with our trade partners as we go, we will be able to better control the production flow of our project. This is important for two reasons:
1. Leveling: If we do not clearly define the work in each Takt area by work package, then we run the risk of it being unbalanced and interrupting the system’s flow. Usually by the assumption of the trade because the GC has not communicated this as a first priority. This does and will continue to result in longer time frames than necessary, costing more money and delaying the project.
2. Takt Control: If we do not clearly identify the work steps in each Takt zone and level them with our trade partners, then we will not have them queued properly in our short-interval processes, and our short-interval commitments may be out of flow. This can either introduce too much variation or too much work in progress that causes a break in the flow.
The more time we spend leveling and work packaging, the better off we will be. Please note, this is not push / command and control. Instead, we are doing this with the trades as we go in a collaborative environment. It will help us to increase the efficiency of LPS & pull plans and free us from this information being hidden in a CPM schedule. All the work is packaged into Takt sequences (also known as trains) and shown together so everyone can see the flow and improve our schedule while allowing the trades the time they need.
It’s like a game of whack-a-mole; if there is some activity, scope, or work package duration that is larger than the others, then this is your bottleneck to achieving a better throughput. It is defining how much flow you can achieve on your project. So, the idea is to find the way to “whack-a-mole” until it is as level as possible with the resources available. We don’t whack the trades, we whack the old processes and ways of managing construction durations together with our trade partners.
So, in conclusion: Are you leveling the work? If not, why not?