The Three Things Our Industry Needs! Feat. Hal Macomber

Are You Measuring Flow? The Three Things Every High-Performing Industry Does That Construction Does Not

Here is a fact that should bother everyone in this industry: construction productivity in North America has been declining since 1987. Not stagnating. Declining. While other industries have grown dramatically in output per worker, per dollar, and per unit of time, construction has moved backward. The tools are better. The technology is more powerful. The workforce is not less capable. And the results are getting worse. Something fundamental is being missed, and it is not a tool or a software upgrade. It is the way the production system is being designed, measured, and improved. That is the conversation that Hal Macomber, a lean construction researcher and practitioner with decades of experience applying production theory to the built environment, brought to this episode of the Elevate Construction podcast.

The Pain Nobody Wants to Own

The standard diagnosis of construction’s productivity problem blames labor costs, material costs, regulation, and supply chain complexity. Those are real factors. They are not the root cause. The root cause is a production system that was not designed according to production laws, that does not use flow as its primary improvement metric, and that ignores the expertise of the people closest to the work when it comes to making things better. The industry is measuring the wrong things, designing systems that create the delays they then try to manage, and leaving most of its collective intelligence untapped.

The Failure Pattern

The pattern shows up on almost every project in an almost identical way. The schedule is built around CPM logic, which tells you what to start and when, without governing the pace at which trades work or the rhythm of handoffs between them. Trades are pushed into work as soon as their predecessors finish, regardless of whether the downstream trade is ready to receive the work or whether the upstream trade can sustain the pace. When variation hits, and variation always hits, highly utilized crews have no response capacity. One delay cascades into the next. The project lengthens. More people are added to compress the schedule. Utilization goes up. Variation stays high. Delay compounds. The system produces the result it was designed to produce, which is not flow.

The Gap Is a Design Problem

The people doing this work are not failing. The system they are working inside was never designed for flow. A foreman who is managing a crew in a space where two other trades are also working is not incompetent. They are surviving a production design that put too many things in the same space at the same time because the schedule said it was possible, not because the physics of work said it was. A superintendent who is firefighting material delays is not disorganized. They are managing the consequences of a procurement system that was never synchronized to the production rhythm. The system failed them. The job is to fix the system.

What Two Identical Towers Proved

Hal Macomber and Corey Hackler, now a lean leader at DPR Construction, worked together in the early 2000s on a project in La Jolla, California involving two identical bed towers. The senior superintendent on one tower managed to the CPM schedule, starting everything when the schedule said to start it. Corey took a different approach on the second tower, focusing on flow rather than starts. The result was measurable and striking: the flow-managed tower started one month later and finished two and a half months earlier. Same building. Same trades. One production philosophy created a dramatically different outcome.

This is the proof of concept that the industry has had access to for more than two decades and has not fully acted on. Takt planning, which governs the pace and rhythm of trade handoffs rather than simply tracking start dates, was the framework that made flow possible on that tower. The trades made a commitment to each other: by 9 a.m. Monday morning, the space will be ready for whoever is coming in next. That commitment, grounded in a shared rhythm and enforced by mutual accountability, is what flow actually looks like in practice.

Three Things the Rest of the World Is Doing

Hal identifies three practices that high-performing industries use consistently and that construction, for the most part, does not. The first is using flow as the principal improvement measure. This means that the question driving every decision is not whether the schedule has green bars but whether work is actually moving steadily through the production system without stopping, waiting, or stacking. The second is designing the production system based on production laws, specifically Little’s Law, Kingman’s formula, and the law of variation. Most construction professionals have not studied these laws and are therefore designing systems that violate them, without knowing why the results are so consistently poor. The third is tapping into the expertise of the whole workforce. The people handling the material, using the tools, and doing the physical work know exactly where flow is breaking down. Construction, by and large, does not ask them.

Why Kingman’s Formula Changes Everything

Kingman’s formula describes the relationship between utilization and variation in producing delay. When crews are fully utilized and variation is high, delay does not increase linearly. It curves toward infinity. Think of highway congestion before the pandemic: a road that is 70% utilized handles variation smoothly. A road at 95% utilization turns a single tapped brake light into a traffic jam that lasts six hours. Construction sites run at high utilization by design, because the CPM schedule pushes as much work forward as fast as possible. When variation enters a system at that utilization level, the delay it produces is far greater than intuition suggests. The only countermeasures are reducing variation, reducing utilization by building in capacity buffers, or both. Takt planning does both simultaneously.

What Takt Actually Does That CPM Cannot

Takt is not a more sophisticated version of CPM scheduling. It is a different production design philosophy. CPM tracks starts and finishes in sequence. Takt governs pace and rhythm. CPM allows work to stack in spaces. Takt prohibits it by design. CPM does not require trades to coordinate their pace with each other. Takt requires it explicitly. The fishbone analogy that Hal describes captures the structure clearly: the Takt backbone governs the rhythm of the whole project, and everything else, materials, labor, information, inspections, is pulled to that rhythm. The backbone is flow. The ribs are what is pulled to support it.

Little’s Law adds the mathematical foundation. When batch sizes are smaller, lead times are shorter and waiting time decreases. A trade that finishes its portion of a floor in two days and hands off rather than finishing the whole floor in five days and then handing off creates opportunities for downstream trades to enter the space sooner, reduces the amount of work in process, and shortens the overall project duration. The counterintuitive insight is that finishing faster by doing less at a time produces better outcomes than pushing as much work forward simultaneously as the schedule will allow.

Here Is What to Start Measuring on Your Project

Before running another weekly schedule update, ask these questions about flow instead:

• How many times did a trade stop work today because the space was not ready, the material was not available, or the information was missing?
• Are wagons in your Takt plan starting and finishing as planned, not just starting?
• Is the number of daily stops trending down from week to week, or holding steady?
• Do your crews have capacity buffers built in so that variation can be absorbed without cascading into the downstream trade?
• Are you tracking flow efficiency across zones, or only tracking whether the overall schedule date is still holding?

If those questions are hard to answer, the production system is not yet measuring what matters.

Built for Every Person on the Project, Not Just the Scheduler

The third of Hal’s three practices is the one most consistently ignored. The people running pipe crews, framing walls, and installing mechanical systems know exactly where flow is breaking down on their portion of the project. They know which handoffs are rough, which materials arrive late, which coordination gaps slow them down every week. A production system that does not capture their input is designing improvements without its best data source. Morning worker huddles, short-interval planning sessions with foremen, and genuine two-way communication about what is blocking flow are not soft cultural initiatives. They are production strategy. If your project needs superintendent coaching, project support, or leadership development, Elevate Construction can help your field teams stabilize, schedule, and flow.

Run Toward These Principles

Hal’s closing advice to the industry is the right one: start practicing. Do not wait for a perfectly repetitive building sequence to try Takt. Take the next non-repetitive scope of work and Takt plan it. Learn the rhythm. Learn the handoff. Learn how variation affects the pace and what buffers are needed to absorb it. Build the expertise before the stakes are at their highest. Jason’s version of the same advice is equally direct: run to these principles, not away from them. Imagine what the industry looks like when it has given Takt planning the same decades of development that CPM has received. That day starts with one project team deciding to measure flow, design accordingly, and engage everyone doing the work. As Iris Tommelein, director of the Project Production Systems Lab at UC Berkeley, stated plainly: Takt applies to all work, even non-repetitive work. There is no scope that is exempt and no project too small to begin.

On we go.

FAQ

What are the three things high-performing industries do that construction does not?

Hal Macomber identifies them clearly. First, they use flow as the principal improvement measure, meaning every decision is evaluated by whether it improves or degrades the steady movement of work through the production system. Second, they design their production systems based on sound production laws, specifically Little’s Law, Kingman’s formula, and the law of variation, rather than intuition or tradition. Third, they tap into the expertise of the whole workforce, including the people closest to the physical work, when identifying where flow breaks down and how to improve it. Construction has access to all three practices and consistently underutilizes them.

What is Kingman’s formula and why does it matter for construction scheduling?

Kingman’s formula describes the mathematical relationship between utilization, variation, and delay. When both utilization and variation are high, delay does not increase proportionally. It compounds toward infinity. A fully utilized crew that encounters variation has no capacity to absorb it and cascades the delay downstream. A crew with some capacity buffer can absorb variation locally and protect the downstream trade from feeling it. The construction implication is direct: CPM scheduling pushes utilization to its maximum because every crew starts as early as possible. This makes the system maximally sensitive to variation. Takt planning builds in rhythm and buffer, which reduces both utilization pressure and the cascading effect of variation.

What does it mean that Toyota’s production line was a flow system, not a pull system?

The distinction Hal draws is important. When people describe Toyota as a pull system, they are describing how material is pulled to the production line based on demand signals rather than pushed in advance. But the line itself is a flow system: every station operates at the same rhythm, governed by Takt time, and work moves steadily from one operation to the next at a consistent pace. The construction parallel is that Takt governs the rhythm of the entire project, and Last Planner pull planning coordinates the short-interval commitments of the trades to that rhythm. They are not competing systems. Takt sets the pace and Last Planner makes the commitments that allow the pace to be kept.

How do you measure flow on a construction project?

Hal offers two complementary measures. The first is whether wagons in the Takt plan are starting and finishing as planned. A wagon that starts on time but finishes late is breaking flow downstream, even if the start metric looks good. The second and more powerful measure is tracking stops: how many times did work fail to proceed because the space was not ready, materials were unavailable, qualified workers were not present, or the preceding trade had not completed their work? Tracking stops and driving that number down over time is a direct measure of improving flow. The goal is not zero variation. The goal is a system that can absorb variation without stopping.

Why does Takt apply to non-repetitive work, not just repetitive sequences?

Hal’s argument is that non-repetitive work is actually the best place to practice Takt, because each sequence only runs once. A mistake in one train does not cascade to twenty subsequent trains. That makes non-repetitive work a lower-risk learning environment where teams can develop the habits, relationships, and timing discipline that Takt requires before applying it to large repetitive sequences where errors are more costly. Beyond the practice rationale, Iris Tommelein’s 2018 statement makes the theoretical case clear: the production laws that Takt honors apply to all work, regardless of whether it repeats. Variation compounds with dependence in any sequence. Rhythm and handoff discipline reduce that compounding in any sequence. There is no construction scope where flow is irrelevant.