When output falls, increasing pressure on the workforce can make the underlying productivity system worse.
A project falls behind schedule. Management adds labour and authorises overtime. The number of people increases, but the work area does not. Congestion rises. Fatigue grows. Rework increases. Safety pressure creates absenteeism. Productivity per person falls, the remaining schedule becomes tighter and management adds more pressure.
The intervention addressed the symptom and reinforced the cause.
This is the central systems lesson in productivity management: observed output is produced by interacting conditions. Treating productivity as an isolated worker attribute can lead managers to optimise the wrong part of the system.
The Strategic Context
Nasirzadeh and Nojedehi developed a system-dynamics model of labour productivity in construction projects. Their work responds to a common weakness in productivity analysis: individual factors such as overtime, weather, technology or change are often studied separately even though the real operating environment contains multiple interacting causes.
The model divides the system into four connected sectors: project workflow, workforce, project duration and cost, and labour productivity. It includes direct and indirect relationships among factors such as fatigue, weather, working-area constraints, skillfulness, project-management efficiency, schedule pressure, rework and workforce policies.
The authors applied the model to a housing-project example and used simulation and sensitivity analysis to explore how changes in influencing factors affected productivity, duration and cost. They explicitly note that more sample projects would be needed to validate the model more broadly. The specific simulated numbers should therefore remain case-specific.
The value for leaders is not the precise output of that model. It is the method of thinking.
What Leaders Commonly Misread
The first misread is that productivity is a property of labour. Workers do matter, but output can be constrained by material availability, space, sequence, rework, management decisions, fatigue, weather, interfaces and equipment.
The second is that adding resources increases output proportionally. When the workplace becomes crowded or interfaces become overloaded, additional labour can reduce productivity per person.
The third is that schedule pressure is merely a motivator. Schedule pressure can change behaviour, quality, safety and rework. The resulting feedback can lengthen the schedule it was intended to recover.
The fourth is that the observed cause is the root cause. A team may appear slow because it is waiting for material, correcting rejected work, working out of sequence or navigating unclear decisions.
Reframing the Issue
Productivity should be managed as a system outcome.
The right question is not “Why are people working slowly?”
It is:
What structure is producing the current rate of useful, accepted output?
That structure includes the flow of work, the quality loop, the resource policy, the physical environment and the management system.
Rework Creates a Reinforcing Loop
The project workflow in Nasirzadeh and Nojedehi's model distinguishes work in progress, accepted work and rework. This is strategically important because gross activity is not useful output.
If schedule pressure increases the probability of rejection or out-of-sequence work, the system can create more rework. Rework consumes the same labour needed to complete remaining work. The completion forecast worsens, increasing schedule pressure further.
This creates a reinforcing loop:
schedule pressure → rushed or disrupted work → rework → lower useful output → more schedule pressure
Managers who measure only hours worked may conclude that effort is increasing. The system is actually converting more effort into failure demand.
More Labour Can Create Congestion
The model also illustrates a common operations principle: capacity has physical and coordination limits.
When the amount of labour exceeds what the available work area can support, productivity can decline because people interfere with each other, wait for access or create additional coordination overhead.
This is not unique to construction. The same logic appears in engineering change systems, software teams, maintenance shutdowns and administrative processes. Adding people to a constrained workflow can increase queues, hand-offs and communication burden.
The constraint must be identified before capacity is added.
Related article: Capacity Is a Strategic Constraint: Match Ambition to What the Organisation Can Absorb
Productivity Is Also a Management Variable
The source model includes project-management efficiency as one of the factors influencing labour productivity. That is a useful corrective to cultures that locate productivity responsibility only at the front line.
Management affects sequence, material availability, decision speed, work clarity, supervision, resource balance, quality systems and the response to schedule pressure. These conditions shape the environment in which labour performs.
A productivity problem can therefore be an executive design problem expressed through worker output.
Decision Framework: Diagnose Before You Push
When productivity falls, use a six-layer diagnostic before increasing labour or overtime.
1. Useful output
What quantity of accepted work is being completed, not merely started or touched?
2. Flow constraint
Where is work waiting? Look for material, information, equipment, approval, access, predecessor work or specialist capability.
3. Rework loop
How much capacity is being consumed correcting prior work, and what is generating the defects or rejection?
4. Resource interaction
Would more labour increase throughput or increase congestion and coordination overhead?
5. Human condition
What role do fatigue, skill mismatch, motivation, absenteeism or safety pressure play?
6. Management condition
Which management decisions, delays, sequencing rules or information failures are producing the current behaviour?
The purpose is not to avoid accountability. It is to assign accountability to the correct part of the system.
From Strategy to Execution
Immediate action is to stop using a single productivity number as the diagnosis. Pair it with rework, waiting time, work-in-progress, constraint utilisation and overtime data. Observe the process directly before choosing an intervention.
Medium-term capability building means mapping causal relationships in high-variability operations. Teams do not need sophisticated simulation for every problem. Even a simple causal-loop discussion can reveal that a proposed intervention may create a delayed counter-effect.
Long-term strategic positioning involves developing operational leaders who can distinguish local efficiency from system throughput. This is especially important in project environments where every function can appear busy while the overall completion rate deteriorates.
Signals to Monitor
Warning signs include rising overtime with flat accepted output, increasing workforce without proportional throughput, growing rework, schedule recovery plans that repeatedly add pressure without removing constraints, more work-in-progress but slower completion, and productivity discussions focused mainly on worker effort rather than flow conditions.
Positive signals include stable useful output, falling rework, visible constraints, deliberate work-in-progress control and recovery actions that change the system rather than merely demand more effort from it.
References
- Nasirzadeh, F. & Nojedehi, P. 2013, 'Dynamic modeling of labor productivity in construction projects', International Journal of Project Management, vol. 31, no. 6, pp. 903–911.
Questions for the Leadership Team
- What is the actual constraint on useful output in our most important operation or project?
- How much capacity is currently consumed by rework or waiting?
- Where could adding labour or overtime reduce productivity rather than improve it?
- Which management decisions are shaping the productivity conditions experienced at the front line?
- Are we measuring activity, gross output or accepted value-producing output?
- What reinforcing loop could make our current recovery plan worse over time?
Closing Perspective
Productivity is rarely improved sustainably by demanding that one part of the system work harder. Leaders need to understand the feedback loops that convert management decisions, constraints, human conditions and workflow into accepted output. The worker is part of that system, but the worker is not the system. When productivity deteriorates, diagnose the structure before increasing the pressure.
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