Introduction
The Priority Number is a dynamic metric calculated as of the current date, reflecting the urgency of tasks within a project. Rather than focusing solely on the task’s deadline, it accounts for the pressure imposed by the entire chain of dependent tasks leading to future milestones. A task might seem manageable when viewed in isolation, but its Priority Number can increase if subsequent milestones in the chain are under significant time pressure.
Additionally, the color of Gantt chart bars visually represents the feasibility of the task’s associated chain within the project. This feasibility is determined by assessing the available time and workload across all tasks in the chain between milestones. Colors range from green, indicating a feasible timeline with available buffer, to red, signaling tasks that are likely to miss their milestones. This system helps teams anticipate and address project constraints before they escalate.
Task constraint dates also influence Priority Numbers, but they do not impact the Gantt bar color, which is determined solely by milestones.
Example
1. Task Example: Electrical Assembly (Priority 90 – Yellow)
Despite having a green Gantt bar, the task Electrical Assembly has a priority of 90 (yellow). This occurs because the critical path to the second milestone imposes more pressure than the first milestone. Although the critical path to the first milestone appears feasible, the second milestone’s tighter constraints increase the task’s priority. In such cases, you might consider moving the first milestone earlier to reduce pressure on subsequent tasks.
2. Task Example: Module Welding (Priority 68 – Green)
In contrast, Module Welding has a priority of 68 (green) but a yellow Gantt bar. The Gantt bar is yellow because the task is part of a critical path between the first and second milestones, with less than 20% float or buffer. The priority of 68 is lower than 80 because it’s calculated based on the remaining work within its critical path, assuming the task could start immediately with all its predecessors completed.
#Screen 1 The difference between task priority and Gantt bar color
General Rules for Task Priority and Gantt Bar Interpretation
1. A task’s priority number is calculated based on workload in the critical path, time pressure, and both milestones and task constraint dates. The Gantt bar appearance reflects the feasibility of the task’s critical path between milestones only, considering intermediate milestones within the task chain.
2. A task can have a high priority number even if its nearest milestone appears feasible. This occurs when future milestones impose higher time pressure, making the task more urgent.
3. Tasks on the critical path will show reduced scheduling flexibility if there is limited time available between milestones. A task’s Gantt bar appearance may be affected even if its priority number is moderate, due to constraints elsewhere in the task chain.
4. If a task’s nearest milestone seems achievable but its priority is still high due to time pressure from future milestones or constraint dates, consider adjusting earlier milestones or redistributing workloads.
5. Task priority is calculated as if the task could start today, assuming all predecessors are complete or that preceding constraint dates do not exist. This approach forecasts potential delays across the task chain.
6. Priority numbers help identify tasks requiring immediate attention, while Gantt bar appearances evaluate task feasibility based on milestone-driven constraints.
Possible date range – Advanced
Possible Date Range refers to the earliest and latest dates within which a task or project can realistically be scheduled, considering all relevant constraints. These constraints may include task dependencies, resource availability, milestone deadlines, and task-specific constraint dates.
In project management, the possible date range indicates the time window during which a task can be started and completed without violating critical scheduling rules. It serves as a guide for determining whether tasks can be delayed, accelerated, or re-sequenced while maintaining overall project feasibility.
Key factors influencing the possible date range include:
• Earliest Start Date: The soonest a task can begin, determined by task dependencies.
• Latest Finish Date: The latest a task can be completed without delaying dependent tasks or violating constraints.
Managing Possible Date Ranges and Task Prioritization
In some project scenarios, the Possible Date Range requires special attention due to how parallel tasks are prioritized. Consider the example below where three tasks run in parallel under the first project summary:
• Electrical Assembly (prio 104), the most critical task requiring urgent attention.
• PLC Programming (prio 101), reflecting pressing importance.
• Module Programming (prio 96), showing only a small possible date range, even though one might expect its timeline to extend to match Electrical Assembly (prio 104).
One might argue that the task Module Programming (prio 96) should have its possible date range extended to match the length of Electrical Assembly (prio 104), suggesting that PLC Programming (prio 101) should not be critical if a slight delay wouldn’t impact the final delivery date.
However, as a consequence of Epicflow’s Priority Calculation, which considers only successor tasks and not parallel ones, PLC Programming (prio 101) remains critical if its successors are at risk, even after completing Electrical Assembly (prio 104).
This approach differs from Goldratt’s Critical Chain Method, where feeding buffers are calculated for each parallel task. This results in lower priorities for parallel chains until a delay becomes significant enough to impact the overall schedule. While this can create an optimistic view, showing progress on the critical path while masking potential risks in parallel tasks, it often results in last-minute crises when delays accumulate unexpectedly. This phenomenon is explained in this article: “Once in Red, Always in Red”.
How Epicflow Manages Task Load Distribution and Risk Awareness
The Epicflow approach ensures that project managers stay aware of potential risks before they escalate. This is reflected not only in the priorities or the colors of the Gantt bars but also in the Future Task Load view. As long as the task chain remains feasible, the load is distributed across the Possible Date Range. However, if the chain becomes unfeasible, the load from the remaining work that cannot be distributed is shifted to the start constraint of the chain.
Example
Consider two consecutive tasks, each requiring 40 hours:
• The first task is handled by an engineer.
• The second task is executed by a production employee.
Both tasks must be completed within two weeks, meaning the daily task load at the start is 8 hours per day for two weeks, with a priority of 100.
If after one day, the engineering task hasn’t started, the priority increases to 101. The question now is how to handle the 8 hours that no longer fit within the possible date range.
Distributing these hours across the entire task chain might seem reasonable at first, but over time this accumulates at the last task in the chain, causing a bottleneck toward the end. This mirrors a common issue in many organizations where tasks appear manageable at the beginning, but delays cause last-minute rushes and cost overruns.
To prevent this, Epicflow assigns the extra 8 hours to the start constraint of the chain. This approach signals immediate action rather than pushing the delay downstream, helping teams address issues early and avoid unnecessary costs.
By proactively reflecting these risks in both the Gantt and Future Task Load views, Epicflow supports better decision-making and keeps projects on track.