Modern organizations operate in environments where efficiency, adaptability and resilience are essential. Two of the most influential process improvement theories provide structured ways to achieve these: the PDCA cycle (Plan–Do–Check–Act) from LEAN thinking and the Five Focusing Steps from the Theory of Constraints (TOC).
Both represent continuous improvement cycles, but they approach change from different angles: one emphasizes ongoing incremental progress, the other strategic focus on bottlenecks.
The PDCA Cycle and Kaizen
The PDCA cycle, sometimes called the Deming Cycle, lies at the core of LEAN. It provides a structured, iterative way to improve processes step by step:
- Plan – Identify a problem, analyze its causes, and design an improvement.
- Do – Implement the improvement on a small scale.
- Check – Measure the outcomes and compare them with expectations.
- Act – Standardize the successful change or adapt the plan and repeat.
This cycle repeats continuously, fostering what LEAN calls Kaizen — a culture of everyday improvement. Instead of waiting for major projects, employees are empowered to make small, incremental changes that collectively lead to significant long-term gains.
Key benefits of PDCA/Kaizen:
- Problems are tackled systematically, not reactively.
- Improvements are tested before large-scale implementation.
- The organization learns continuously and adapts over time.
The Theory of Constraints: Five Focusing Steps
While LEAN emphasizes continuous improvement across all processes, the Theory of Constraints (TOC) focuses attention where it matters most: the system’s bottleneck. Every process always has a constraint, a specific step that limits overall throughput. Improving anywhere else may bring local efficiencies but will not increase system-wide performance.
The TOC improvement cycle follows five focusing steps:
- Identify the constraint – Find the single process, resource, or step that limits output.
- Exploit the constraint – Maximize the efficiency of the constraint with existing resources.
- Subordinate everything else – Align other processes to support the constraint, avoiding overload or idle time.
- Elevate the constraint – Increase capacity or make investments to relieve the bottleneck.
- Repeat the cycle – Once the constraint is resolved, a new one will emerge.
This approach ensures improvement efforts are not scattered but concentrated on what truly governs system performance.
Two Cycles, One Goal
Although PDCA and TOC differ in focus, they are complementary:
- PDCA (Kaizen) ensures continuous, organization-wide learning and gradual waste elimination.
- TOC ensures that improvement efforts target the most critical point of the system.
Together, they create a powerful framework: incremental improvements build momentum, while bottleneck analysis ensures resources are applied where they deliver maximum impact.
Why This Matters in Logistics and Supply Chains
In complex logistics systems, bottlenecks are common — whether at warehouses, ports, border crossings or in transport capacity. At the same time, inefficiencies can accumulate across everyday tasks.
- PDCA/Kaizen can streamline warehouse layouts, standardize loading processes, or improve data accuracy.
- TOC ensures that investment and management attention focus on the true constraint — for example, a congested port terminal or a rail capacity limitation.
By having knowledge, understanding and practical experience with applying improvement cycles, logistics systems become not only more efficient but also more resilient and adaptable to changing conditions.
For LOBRA, these improvement cycles provide tools to make corridor planning dynamic. Together they help ensure transport corridors evolve towards greater efficiency, resilience, and sustainability.
Project number: 404191