Balanced Production: A Tale of Time and Money

Takt Production for Lean Construction

It’s no secret that the methodology used to both manage and sustain labor and resources when it comes to production management has been evolving for centuries. And why is that? The most obvious answer is time. The necessity to get things done faster and more efficiently is always a driving force when it comes to developing a production model that can withstand the test of, well, time itself. It is, after all, the one thing we never have enough of, so it makes sense to continue striving for improvement directly on its behalf.

What’s the other driving force that has been keeping our production managers up all night for centuries? Money, of course. And I see no need to go into the obvious reasoning behind that.

So, that leaves us with time and money. How do we make the most of what we have and ensure a balanced production flow that optimizes capacity in both of these arenas?

Where It All Began

The Papyrus Production Matrix

The origin of the production model dates back to nearly 4,000 years ago. You could say this is where it all began… an ancient papyrus production log detailing the logic and application theorems used to erect the awe-inspiring Pyramids of Giza. 

In this example, we have 40 workers in larger group pairings performing their specific tasks, in the predetermined sequence, laid out by the production manager. The goal, of course, being accomplishment in a timely manner. But time looked very different then than it does now. The stone blocks, for example, were quarried and delivered via canals excavated from the Nile River to the pyramid site. However, these canals contained water only during high water periods throughout the flood season. The boats carrying the stone blocks excavated from the river were then floated within a few hundred meters of the construction site for unloading. And this was done as the tide allowed. We also have record of all work, supplies, meals, lodging and health care for workers depending on the capacity of the teams and the work assigned. 

What did we learn from this model? Mass production (in general) requires a balance of logistical supplies, crew support, elemental/seasonal influence, available crew work capacity and work demand to achieve optimum efficiency, given the circumstances.

Moving on to the 16th century, we start getting into wartime production with the Arsenal of Venice – a group tasked with building large numbers of commercial vessels and warships based on a production methodology that demanded continuous and uninterrupted flow of labor and resources. This is also where we see our first example of assembly line production: As soon as the hull and frame assembly were complete, that ship went on to the next station in the assembly line and the next ship was laid down.

What did we learn from this model? If production management is unable to remove variability in supply flow, then having sufficient material and sub-assembly inventory offers a standard “solution” to supply variability. 

And what did keep from this model? Not only did we continue to evolve the Venetian-inspired assembly line, the Venetian shipbuilders also proactively preconstructed the hull frames of popular models. This gave them a pre-existing inventory of commonly ordered frame assemblies and limited the likelihood of possible interruptions in production flow. Today, we refer to this as a material inventory (WIP) buffer and its job is to offset the potential variability in available supply.

And finally, we make our way to the most well-recognized version of the assembly line production model with Ransom Olds, which was later improved upon by Henry Ford. Ford famously remarked that the use of the moving assembly line allowed for the work to be taken to workers rather than the worker moving to and around the vehicle, but it was still very similar to and retained its influence from the Venetian style of production used by the wartime shipbuilders.

And the most important thing? It saved a tremendous amount of time!

The Beat of a New Drum

The Takt Construction Schedule

Starting in the 1920s and extending well into the production methodology used throughout World War II, manufacturing was introduced to the takt construction schedule. The word “takt” comes from a German word associated with keeping a musical “beat” and was used by Junkers Aircraft as early as 1926 in describing their takt production manufacturing methodologies. In Junkers concept, aircraft manufacturing was timed so that the airplane assemblies moved from one production station to the next station at fixed intervals or takt time. Consequently, the aircraft moved in time with a pre-determined takt production beat through the different stations rather than a continuously moving Ford-style assembly line.  

It didn’t take long for Japanese manufacturing companies like Mitsubishi and Toyota to catch on, but it was Toyota specifically that combined takt production with flow production to form the foundation for its Just-in-Time (JIT) Production System. What’s the big difference here? Rather than producing goods and supplying customers from stock, the JIT system focus on producing exactly the amount you need at exactly the time your customers need it.

JIT production is very similar to lean construction in that both are very focused on takt timing. However, the lean construction model focuses heavily on the customer, while JIT retains its focus predominately on the business.

Meanwhile, in the construction industry, Line of Balance (LOB) production scheduling systems were employed in building construction and documented as early as 1929, when the builders of the Empire State Building famously used takt-related LOB concepts in erecting the steel and exteriors of the world-renowned structure.

Production Gets Critical

Takt Production Keeps Evolving

Evolving once more in the essence of time, the standard production schedule gets revolutionized yet again with the Critical Path Method (CPM) introduced in 1962. Replacing Line of Balance, Gantt charts and other methods of construction schedule planning, CPM caught on at warp speed primarily due to its capacity to calculate the completion date. In a general sense, however, CPM does not address production of work, but rather indicates the logical path of construction required to complete the work. 

Another challenge? CPM implementation involves segmenting the building program into multiple “zones” of construction effort, with detailed representation of the trade sequence through each of the work zones. This approach results in large networks of interlinked, short-duration tasks affiliated with both work zone and trade that must be sorted, printed and then distributed to trades for their operational planning. Construction schedules are often expressed as even more detailed sub-tasks for each activity within a work zone. The result? You often end up with a construction schedule that details 20 or more work zones, with 50-70 production sub-tasks for each zone, which produces a network-linked Gantt chart output of one or sometimes two pages for each work zone. And this ultimately results in 40-80 printed letter size pages the management teams must navigate through to manage their teams “efficiently.”

And, again, this takes time. It takes time to build and interweave the complexities of this type of construction schedule – most often 2-3 days.

Production Gets Balanced

Gill’s Version of Takt Production

Trades, whether brought onto the project as trade crews of the general contractor or as trade crews of subcontractors, desire to optimize their efforts on their portion of the project to reduce expenses and increase profit margins.  Also, trades seek stable resource utilization with limited peaks and valleys. The construction schedule manager, on the other hand, desires to turn over the completed works according to the need of the building developer – the ultimate customer in the project. What is needed for effective construction scheduling is a production management and control program that encourages all team members to work congruently to satisfy both of these project goals.

In the late 1950s and early 1960s Paul Gill developed a construction scheduling approach for the delivery of subdivisions of single-family homes and published information about the approach in a trade magazine article in 1965. The delivery program was similar to the ship building approach of the Arsenal of Venice in that once the foundation of the first home in the subdivision was completed, the foundation crew moved to the next home while the framing was started on the first. 

The key insight from Gill was that takt and lean construction managers could view and assess the progress of the entire subdivision works using a program control chart. This chart displayed the advancement of the program flow curve leading the edge of the work effort for each home as trade crews moved from house to house. And this influenced the industry standard for some time.

Since 1983, the Construction Industry Institute (CII) has worked to improve construction scheduling performance on industrial and petrochemical projects by establishing the basic concept of work face planning (WFP) and work packaging. The ultimate goal here is to reduce costs and save time by minimizing logistical constraints of information, tools, equipment, and materials at the “work face” to improve construction schedules and trade productivity.  

Gill’s residential production model highlights that repetitive and semi-repetitive work may be viewed in a takt production matrix (TPM) format. Here, the columns represent the takted work for each trade through all work zones of the project following the path of construction throughout the facility.  And, of course, the evolution continues:

• The International Group of Lean Construction (IGLC) and the Lean Construction Institute (LCI) help construction professionals implement the Last Planner System first described by Ballard in 1992.
• The Project Production Institute was formed in 2014 to bring production science to the construction industry.
• Short Interval Production Scheduling is presented at the ASA conference in 2017.
• Location Based Flowline Scheduling is introduced as a methodology to better manage both repetitive and semi-repetitive production efforts.
• And finally…

Production Gets Clear

“To make fundamental improvement in the production process, we must distinguish product flow (process) from workflow (operations) and analyze them separately,”

~Shigeo Shingo.

The Clear Flow Matrix concept, now available to the construction industry through a takt production software application, was born out of the necessity for a more efficient management tool for takt construction workflow. It combines the terminology of lean construction, the timing of takt construction and the logic of CPM to provide a truly efficient snapshot of your takt production matrix. It takes the detail of the Gantt chart and condenses it into a one-page overview of the entire construction schedule that is navigated by pacemakers and areas in a manner that ensures a collaborative and coherent production flow. And, most importantly, it saves a tremendous amount of time and money – our two most coveted resources:

• Time: Build your master schedule in just 2-3 hours versus the typical 2-3 days required for the traditional Gantt chart matrix.
• Money: Complete tasks on time and ensure a continuous flow with no costly bottlenecks.

For more information, visit us at the 2022 Lean Conference!

Clear Flow Matrix: A Clear Flow for Takt Production