Introduction
Partial concurrency occurs in construction when multiple delays overlap, but not all delays equally impact the critical path or the project’s completion. In other words, while two or more delays might happen during the same time period, only one delay affects the project’s critical path, and the other affects non-critical tasks or has a lesser impact on the project schedule.
Partial concurrency is different from true concurrency, where multiple delays simultaneously affect the critical path. In partial concurrency, one delay is the primary reason for the project being delayed, while the other delay(s) occur in parallel but may not independently push out the project completion date.
1. Key Characteristics of Partial Concurrency
- Simultaneous Occurrence: Multiple delays happen during the same period, overlapping in time.
- Impact on Critical Path: One delay impacts the critical path directly, while the other delay affects non-critical tasks or causes less delay to the project.
- Different Levels of Impact: The delays do not contribute equally to the overall project delay.
2. Example of Partial Concurrency
Scenario:
In a construction project for a residential building, the following delays happen during the same two-week period:
- Owner Delay: The owner delays providing approval for the final interior design by two weeks, directly impacting the contractor’s ability to start interior finishing work (a critical path activity).
- Contractor Delay: The contractor is two weeks late in starting non-critical landscaping work around the building due to a shortage of labor.
While both delays occur during the same two-week period, only the interior finishing delay caused by the owner impacts the critical path and pushes the project completion date. The landscaping work delay caused by the contractor does not directly affect the overall project timeline because it is not on the critical path. This is a classic example of partial concurrency.
3. Difference Between Partial Concurrency and True Concurrency
| Aspect | True Concurrency | Partial Concurrency |
|---|---|---|
| Delays Impact | All concurrent delays impact the critical path | Only one delay impacts the critical path |
| Contribution to Project Delay | Each delay could independently delay project completion | One delay primarily drives the project delay |
| Liability and Responsibility | Shared responsibility for all delays | Responsibility typically falls more on the party causing the critical path delay |
In true concurrency, all overlapping delays are equally significant in causing a project delay. In partial concurrency, however, one delay has a more direct effect on the project’s completion, while the others are secondary.
4. Implications of Partial Concurrency
Partial concurrency can complicate delay claims, project responsibility, and dispute resolution. It raises important considerations regarding who is responsible for the delays and whether any party is entitled to an extension of time (EOT) or financial compensation.
A. Extension of Time (EOT)
- The contractor may be entitled to an extension of time for the period caused by the delay affecting the critical path (e.g., the owner’s delay).
- The contractor would not necessarily be entitled to additional time for the non-critical delay (e.g., the contractor’s delay on landscaping).
B. Delay Damages
- Contractor-caused delays on non-critical path activities are usually not grounds for compensable damages if they do not extend the project timeline.
- In contrast, if the owner’s delay on a critical path activity is the primary cause of the project delay, the contractor might be entitled to compensation for costs incurred during the delay.
C. Risk of Claims
- The existence of a contractor-caused delay, even on non-critical work, could potentially reduce the contractor’s ability to claim full damages for owner-caused delays. The owner may argue that the contractor was also responsible for part of the delay, though this argument is weaker in partial concurrency than in true concurrency.
5. Delay Analysis in Partial Concurrency
In partial concurrency cases, delay analysis techniques can help distinguish between delays affecting the critical path and non-critical delays:
A. Window Analysis
- Breaks down the project into smaller time windows to examine delays and their impacts in each period. It helps to identify which delay caused the primary impact on the critical path.
B. Time Impact Analysis
- A detailed analysis that models the effect of each delay on the project schedule. It shows the impact of the critical path delay versus the secondary, non-critical delays.
C. Critical Path Method (CPM)
- CPM analysis helps determine which activities are on the critical path and which are not. This analysis can clearly show how the primary delay affected the overall project completion date.
6. How to Manage Partial Concurrent Delays
Properly managing partial concurrent delays can help minimize their impact on the project schedule and avoid disputes:
- Clear Scheduling and Tracking: Ensure that all delays are well-documented, and the critical path is clearly defined in the project schedule.
- Effective Communication: Both the contractor and the owner should maintain open lines of communication to ensure that delays on non-critical tasks do not worsen over time.
- Proactive Delay Mitigation: Contractors should try to mitigate their own delays, even if they are not on the critical path, to avoid complicating delay claims.
- Risk Sharing Agreements: Having clear contractual provisions for handling partial concurrency delays can help avoid disputes. For example, the contract can state that the party responsible for critical path delays bears more responsibility for the delay.
7. Legal Considerations in Partial Concurrency
A. Responsibility
In partial concurrency situations, courts and arbitrators often focus on determining which delay had the greatest impact on the project. If one party’s delay primarily affects the critical path, they may be held responsible for the bulk of the project delay.
B. Compensation Claims
The contractor can usually claim an extension of time if the owner’s delay affects the critical path. However, if the contractor also experiences delays, even on non-critical activities, it could reduce the likelihood of receiving financial compensation for those delays.
C. Contractual Terms
Contracts should specify how partial concurrency is handled. Standard contract forms such as the FIDIC or NEC contracts often include provisions that can address concurrent delays, but these may need to be tailored to address partial concurrency situations more explicitly.
Conclusion
Partial concurrency refers to situations where multiple delays overlap, but only one affects the critical path, while the others are less significant or affect non-critical tasks. This is different from true concurrency, where all delays simultaneously affect the critical path and contribute equally to the overall project delay.
Managing partial concurrency involves accurately tracking delays, analyzing the project’s critical path, and ensuring clear contractual terms to avoid disputes. When disputes arise, partial concurrency often places the greatest responsibility on the party causing the delay to the critical path, although secondary delays must still be accounted for. Proper planning and communication can reduce the risk of partial concurrency and its impact on a construction project.
