Project Scheduler
Project Scheduler
At the heart of Fusion Online is the Project Scheduler—the system responsible for transforming your network of tasks, resources, and endpoints into a fully scheduled model. Whether you are creating a project for the first time, updating its status, or responding to significant changes, the Project Scheduler ensures that the dates and indicators in your project schedule reflect reality and provide actionable insights for successful planning and execution.
What is the Project Scheduler?
The Project Scheduler works in Fusion Online and Fusion Desktop to:
Create and size buffers
Calculate the critical chain
Resolve resource constraints
Estimate task start and finish times
Determine task criticality
Provide buffer and resource analysis data
Every time you click:
Reschedule — to build a new schedule or fully restructure the project,
Update Schedule — to reflect the latest progress and recalculate status,
the Project Scheduler re-analyzes all your project's data.
Update and Reschedule
Fusion Online provides two key scheduling actions: Update Schedule and Reschedule. Both are used to refresh task and buffer dates, but serve different purposes.
Reschedule is required when scheduling a project for the first time — after you've added at least one endpoint and linked tasks into the network. It is also used when the project has undergone significant structural changes, such as new tasks, major modifications to dependencies, or the addition of endpoints. Rescheduling resets and resizes all the buffers.
Update Schedule is the action you’ll use regularly as part of project execution. It performs a forward-looking scheduling pass from the current status date, recalculating task and buffer projections. Updates are typically done on a recurring basis (such as weekly) to reflect progress and adjust schedules.
Status Date
The status date is the starting point for task scheduling, load leveling, and buffer insertion and updating. You can use the current date and time to schedule from "now," or specify any other date.
If you're making structural changes to a project and want to compare the results of rescheduling, use the Use Last Status Date option. This ensures that the comparisons are meaningful, as they’re based on the same starting point.
When you open the Reschedule or Update Schedule dialog, by default Fusion Online sets the status date to 8:00 a.m. on the current day. Unless you're updating frequently with very short tasks, it's generally best to leave the time set to either the start or end of the day, in alignment with your project calendars.
Resequence Tasks
Every time a schedule update is performed, Fusion Online repositions tasks to ensure no resources are overloaded. By default, the order of tasks is maintained from the last full reschedule to preserve consistency and avoid team confusion.
However, selecting the Resequence Tasks checkbox triggers a new optimization pass that may improve load leveling and task sequencing. This can result in earlier projected project completion, reduced buffer consumption, but also more noticeable shifts in task timing.
Because of the potential for significant shifts in timing, Resequence Tasks is unchecked by default. If you enable it once, the new optimized order is preserved for future updates—even if you uncheck the option later.
What the scheduler does (at a glance)
Buffers
Creates, sizes, or resizes project buffers for endpoints, and calculates current buffer consumption and status.
Critical chain
Identifies the longest path considering dependencies and resource limitations
Task times
Projected Start/Finish, ASAP, and Expanded dates
Criticality
Calculates Criticality and Criticality Ratio for every task
Resources
Levels resource assignments and computes load data for resource views
Fever chart
Produces new status points, buffer consumption, and landing zone data
Project history
Creates history snapshots for comparison
Credibility score
Updates the project’s credibility score and generates a credibility report
Building the schedule
1. Project scheduling
The scheduler takes into account:
Task durations (including focus and low-risk durations)
Task dependencies (links and logic)
Resource limitations (including availability and calendars)
Calendars (working/non-working time)
User-defined priorities, including:
Endpoint priorities (used to determine which endpoint takes precedence when tasks feed multiple endpoints)
Task scheduling priorities (user-defined task-level priorities to help the scheduler make better sequencing decisions when resolving resource conflicts; see Scheduling priorities)
It determines:
When tasks could start (ASAP times)
When tasks should start (Projected Times)
How critical each task is in driving the schedule
2. Buffer sizing
Fusion Online inserts project buffers after each endpoint.
Buffer sizes are calculated based on:
The variability along the longest chain feeding the endpoint
The integration risk where multiple chains merge
The buffer size options configured in the project’s Project Options
For more details on buffer logic, see the Buffers and endpoints concept article.
3. Resolving resource contention
When tasks require shared resources, the scheduler:
Evaluates available units based on resource calendars and resource limits
Moves tasks in time to level load and avoid overloads
This resource-leveling output feeds directly into:
The resource heat map
The resource load graphs
Task start and finish dates
Scheduling outputs
Task-level outputs
Projected Start/Finish
The scheduler’s recommended dates using focus durations, subject to slack, resource limits, and integration risk
ASAP Start/Finish
The earliest possible start and finish dates
Expanded Start/Finish
More conservative dates considering low-risk durations and integration risk
Criticality
How many days from being critical the task is (or 0 if it’s already critical)
Criticality Ratio
A normalized ratio (0 to 100+) showing how close the task is to being critical for its Most Significant Endpoint (MSE) - see Criticality Ratio definition
Dependencies
Calculated task dependencies considering both logical links and resource constraints. The dependencies are used to calculate impact chains and critical chains.
Buffer outputs (per endpoint)
Buffer Size
Initial buffer duration (based on variability and integration risk)
Buffer Left
Amount of buffer time remaining
Buffer Consumed
Amount of buffer time used so far
Chain Complete
% of critical chain completed
Landing Zone
Projected completion window for the endpoint
Status & Trend
Color-coded status and trend based on buffer consumption
Resource outputs
All resource assignment data, load graphs, and heat maps
Calculated per resource and summarized across projects (or in aggregate via templates)
Most Significant Endpoint
When a project has multiple endpoints, individual tasks may contribute to several of them. The Most Significant Endpoint (MSE) for a given task is the endpoint that the scheduler calculates the task will have the most impact on. To calculate MSE, the scheduler uses:
Endpoint Priorities (set in the Endpoints tab)
Or automatically selects the endpoint with the highest risk of delay for the task
The scheduler assigns each task an MSE, which is then used in the calculation of:
Critical Chain
Criticality
Criticality Ratio
Project Scheduler and the Fever Chart
Every time you update the schedule, the scheduler:
Calculates a new status point for the fever chart
Updates buffer consumption data
Adjusts the landing zone estimate
Supports both the traditional fever chart and the time-based fever chart
Project history and credibility
Each schedule run:
Adds a new Project History record
Enables you to run a Network Differences report to compare changes
Recalculates the project’s Credibility Score and Credibility Report based on the chosen Credibility Profile
Advanced scheduling options
Found under Project Options:
Projected Time Mode:
Controls how Projected Times are calculated:
Standard (default)
No Gating: Projected = ASAP times
Max Gating: Aggressively delays non-critical tasks when possible
Maintain Actual Task Dates:
If checked, actual start/finish dates are preserved during scheduling, as much as possible
If unchecked, the scheduler will adjust based on task logic
Be careful: poor data quality can degrade schedule accuracy
Critical Task Options:
Define how Criticality and Criticality Ratio are calculated
Choose between ASAP or Due Date endpoint types (see Endpoint Type section)
Set sensitivity thresholds for identifying critical tasks
Endpoint Type
The Endpoint Type in Project Options determines how the endpoint task of your project is scheduled:
ASAP (As Soon As Possible): The project is scheduled to finish as early as possible, based on task dependencies, constraints, and resource availability. This is the most common mode.
Due Date: Hitting a due date (which may be specified as a task constraint on the endpoint) is paramount. The Criticality Ratio will be adjusted to so that tasks do not appear as critical if their MSE’s date is not in jeopardy. You may specify an explicit due date for a project by attaching a FNLT (Finish No Later Than) task constraint to an endpoint task in Task Details. Fusion Online will backload the schedule to hit that task constraint if possible. This mode is helpful when you're working toward a pre-defined delivery date. Adding a due date to an endpoint can significantly change your project timeline, so make sure the due date is important.
Criticality Ratio (CR)
The Criticality Ratio (CR) is a key metric used by Fusion Online to express how close a task is to becoming critical relative to its MSE and its associated project buffer.
The CR is a percentage ranging from 0 (or less) to 100+, and it is used to:
Prioritize tasks
Assess risk exposure
Aid in scheduling and execution decisions
A task with:
CR = 0 (or less) is on the critical chain
CR = 100 is a full buffer away from becoming critical
Lower CR = Higher priority for attention and task focus
What does it measure?
The CR compares the task’s available slack to the buffer size protecting the endpoint it most significantly impacts, incorporating:
Available slack: How much time the task has before impacting the buffer
Buffer size: The amount of protective time the endpoint needs
By normalizing this relationship into a percentage, Fusion helps managers quickly rank tasks, with tasks having a lower CR warranting more immediate attention.
Formula breakdown
The formula differs depending on the Endpoint Type setting (ASAP or Due Date) defined in the Project Options.
For ASAP-type Endpoints (default)
When the goal is to finish as early as possible:
For Due Date-type Endpoints
When the goal is to finish on time (by a target date):
Where:
Slack = Total slack relative to the MSE
Sensitivity = User-defined value from Project Options
Buffer Needed = Buffer required to protect the endpoint
Buffer Available = Original buffer - buffer consumed
Why is CR Useful?
It provides a more nuanced priority than just looking at slack.
It helps account for how much of the buffer is already used.
It allows teams to focus on tasks that are most likely to cause future buffer consumption.
It adapts automatically depending on whether the endpoint is time-driven (Due Date) or speed-driven (ASAP).
In complex projects, two tasks with the same slack might have very different CR values because of buffer status, making CR a far better prioritization indicator.
Why it matters
The Project Scheduler is much more than a tool for generating dates. It’s:
A model builder, turning task networks into actionable plans
A priority engine, highlighting the most important tasks
A risk management tool, creating buffers that absorb variation
A communication aid, providing visibility for teams and stakeholders
A good schedule helps you make better decisions, deliver reliably, and focus on the most important work.
See also
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