How to Detect & Reduce Bottlenecks in Design and Construction

By Tammy McConaughy, Director, Education & Certification at the Lean Construction Institute

As we settle into the new year, many of us are still riding the momentum of our annual strategic planning. You’ve likely set ambitious goals for 2026—but if you look back at 2025, what were the hurdles that consistently slowed you down?

Process improvement isn’t just about adding new capabilities; it is fundamentally about removing the barriers that prevent flow. In the AEC industry, we often accept delays as “just part of the job.” But starting this year, I challenge you to look at those delays differently: not as inevitable frustrations, but as bottlenecks that can be identified, managed, and eliminated.

What is a Bottleneck?

In the simplest terms, a bottleneck is a point of congestion in a system that limits the overall throughput. Think of it as the “weakest link” or the narrowest part of a pipe. No matter how fast you pump water (or work) into the pipe, the flow is dictated entirely by that narrow section.

In design and construction, a bottleneck creates a constraint where demand exceeds capacity. This could be a physical constraint, like a single tower crane serving a massive site, or an informational constraint, such as an overworked structural engineer who must approve all RFIs before the next phase can begin.

How Do You Know There’s a Bottleneck in Your Process?

Identifying a bottleneck requires looking for specific symptoms in your workflow. If you aren’t looking for them, they can hide in plain sight, masquerading as “busyness.”

Common symptoms include:

• Inventory Pile-Up: You see piles of material waiting to be installed, or in a design office, a massive backlog of “redlines” sitting on one specific desk.
• The “Hurry Up and Wait” Syndrome: Crews or designers rush to finish a task, only to sit idle because the downstream process (the next step) isn’t ready for them.
• High Stress in Specific Areas: If one specific department or trade is constantly working overtime while others leave at 5:00 PM, that overworked team is likely your bottleneck.
• Unpredictable Cycles: When tasks that should take two days randomly take two weeks, there is likely a hidden bottleneck disrupting the standard flow.

How Can Bottlenecks Be Addressed in Design and Construction Processes?

Once you identify a bottleneck, you must act. Ignoring it ensures that every other efficiency you implement will fail to improve the project delivery time.

There are two primary Lean methods we champion at LCI to address these constraints.

Process Mapping

You cannot fix what you cannot see. Process mapping is the visualization of the workflow to identify waste and constraints. By gathering your team to map out the current state of a process (be it the submittal review cycle or the concrete pouring sequence) you inevitably reveal the hidden hurdles.

How it reduces bottlenecks: When you map a process, you often find “loops” (re-work) or steps that add no value (waste). By streamlining these steps and mapping the future state, you can design a workflow that distributes the load more evenly, widening the “neck” of the bottle and allowing value to flow to the customer faster.

Pulling the “Andon” Cord

Originating from the Toyota Production System, the andon cord is a physical or virtual signal that alerts the team to a problem. In a factory, pulling the cord stops the assembly line so the defect can be fixed immediately.

In construction, we don’t always have a physical cord, but the concept is vital. It means empowering anyone on the project—from the apprentice to the superintendent—to stop the line when they see a safety issue, a quality defect, or a process breakdown.

How it resolves bottlenecks: Instead of passing a problem downstream (where it becomes a massive bottleneck later), the andon cord forces the team to swarm the problem and solve the root cause right then and there. It trades a small, immediate delay for the prevention of a catastrophic bottleneck later.

Other Methods to Consider

Beyond mapping and signaling, there are other Lean tools specifically designed to manage constraints:

• Constraint Analysis (The 5 Whys): When a bottleneck appears, don’t just clear it, ask “Why?” five times to find the root cause. This prevents the same bottleneck from reappearing next week.
• The Last Planner System® (LPS): By using make ready planning, we specifically look for constraints weeks in advance. We don’t just hope materials arrive; we track the constraint until it is removed before the work is scheduled to begin.
• Daily Huddles: These short, stand-up meetings allow teams to identify daily micro-bottlenecks (“I’m waiting on an answer from the architect”) and resolve them before they turn into weekly delays.