Why Integration Overcomes the Clash Between Strategic Planning and Collaborative Production

In recent years, some specialized discourses have presented the Critical Path Method (CPM) and Lean methodologies as opposing approaches. In this approach, CPM is associated with rigidity, determinism and disconnection with the work, while Lean is identified with flexibility, collaboration and productive realism. At COMSA Corporació, the progressive incorporation of Lean Construction placed the organization in front of this apparent dilemma: it seemed necessary to decide between CPM or Lean. Analysis from real practice in complex projects led to a different conclusion: the decision was not one or the other, but the combination of both, each in the area where it brings the most value.

Much of this supposed confrontation is based on some recurring myths that should be clarified. One of the most common is to define CPM as a push system. From a technical point of view, this statement confuses planning with production management. The CPM does not decide when the work is activated or how it is executed on the site; Its function is to order activities over time and make their dependencies visible. When work is activated unprepared, the problem is not CPM, but the lack of mechanisms that filter restrictions and capacity. The push or pull character is defined by operational management, not the planning model. Likewise, the tools used to build Gantt charts today allow them to be drawn up based on their milestones and plan backwards.

Another common myth is that CPM generates unbuffered plans and therefore unrealizable. In reality, the method allows you to design safety margins explicitly and clearly separate them from the contractual dates. When plans fail, it’s often because time cushions are hidden within activity durations and stop being consciously managed. CPM, when used well, facilitates precisely the opposite: making these margins visible and controlling their consumption.

Fig. 1. Example of contingency control using explicit buffers in CPM

Fig. 2. Example of CPM with integration of the Takt methodology

Another widespread mistake is assuming that a long-term pull schedule should not be updated and that it is enough to monitor the fulfillment of certain milestones. In complex projects, deviations do not appear abruptly, but progressively. Only a model with explicit dependencies allows us to understand where they are generated, how they propagate and whether they have a real impact on the final term. Updating the schedule does not imply losing the reference, but keeping it alive and manageable.

Effective integration leverages the strengths of each approach. Planning begins through collaborative pull sessions, in which teams define phases, sequences and work trains incorporating flow criteria. During execution, the weekly meetings of the Last Planner System and the lookahead planning allow you to manage commitments, anticipate restrictions and contrast what is planned with what is actually executable.

Fig. 3. CPM – LPS Integrated Methodology Workflow | Tact

All this information from the work is continuously incorporated into a CPM model, which acts as a strategic framework: it maintains global coherence, allows for the analysis of impacts on time, manages baselines and sustains contractual commitments. Far from generating rigidity, this integration turns planning into a living system: Lean provides collaboration, realism and flow; CPM provides structure, traceability and analytical capacity. It is not a question of choosing a methodology, but of combining them to align production, strategy and project commitments.