Understanding how to identify the critical path and calculate float is essential for managing time-sensitive business projects effectively and ensuring strategy execution is aligned with goals.
Critical Path in Network Analysis
What is the Critical Path?
The critical path is the longest sequence of interdependent activities in a project that determines the shortest possible time the project can be completed. Each task in the critical path has zero float, meaning it cannot be delayed without delaying the entire project. Identifying this path is vital for ensuring project deadlines are met.
The critical path outlines the essential activities that must occur on schedule for the project to finish on time.
If any task on the critical path is delayed, the entire project completion date is pushed back.
Multiple critical paths can exist in a project if there are two or more sequences with equal durations.
The concept was first introduced through the Critical Path Method (CPM), developed in the 1950s for managing large engineering projects.
Why Is the Critical Path Important?
The critical path provides key insights into project timelines and resource allocation:
Highlights time-sensitive tasks that need continuous attention.
Allows managers to plan effectively by prioritising work on critical activities.
Helps to predict project duration and track performance against the timeline.
Supports project risk management by showing where buffers and reserves are needed.
In strategic implementation, delays in critical tasks can lead to missed strategic goals, especially if the project is aligned to market opportunities or regulatory deadlines.
Calculating the Critical Path
To determine the critical path, follow these key steps:
Identify all activities needed to complete the project.
Determine activity durations using historical data, expert judgement, or estimations.
Establish dependencies: understand which tasks must be completed before others can begin.
Create a network diagram that visually maps the sequence of tasks and their relationships.
Perform a forward pass through the diagram to calculate:
Earliest Start Time (EST) for each activity
Earliest Finish Time (EFT) = EST + duration
Perform a backward pass to determine:
Latest Finish Time (LFT) for each activity
Latest Start Time (LST) = LFT - duration
Calculate float (explained below).
The critical path consists of activities where:
Total float = 0
EST = LST and EFT = LFT
Example:
Project Activities:
A (3 days) → B (4 days) → D (5 days)
A (3 days) → C (6 days) → D (5 days)
Paths:
Path 1: A → B → D = 3 + 4 + 5 = 12 days
Path 2: A → C → D = 3 + 6 + 5 = 14 days
Critical Path = A → C → D (14 days)
Any delay in A, C, or D will cause the whole project to finish late.
Total Float
Definition
Total float is the maximum amount of time that a task can be delayed without delaying the overall project deadline. It is an important concept for understanding schedule flexibility.
Tasks not on the critical path may have some float, meaning they can be delayed to a certain extent without affecting final delivery.
Formula to Calculate Total Float
Total Float = Latest Start Time − Earliest Start Time
Or
Total Float = Latest Finish Time − Earliest Finish Time
If total float = 0, the task is on the critical path.
Example:
Task X:
EST = Day 5
LST = Day 8
Total Float = 8 − 5 = 3 days
This means Task X can be delayed by up to 3 days without affecting the project's completion.
Importance of Float
Understanding float enables businesses to:
Optimise resource allocation: Resources can be shifted temporarily to critical tasks.
Build flexibility into the schedule: Avoid last-minute rushes or inefficient multitasking.
Manage project risks: Helps in identifying slack time where tasks can absorb minor disruptions without impacting the end date.
Make informed decisions: Useful when facing staffing shortages, equipment delays, or supplier issues.
Amending Network Diagrams in Response to Changes
Projects are rarely static. Changes in timing, resources, or scope demand an update to the network diagram to maintain control over the strategic implementation process.
When Tasks Are Delayed
Task delays are common, but their impact depends on whether they lie on the critical path:
Critical path tasks:
Delay causes direct extension of the entire project timeline.
Managers may need to use crashing techniques (e.g. adding resources to speed up completion).
Non-critical tasks:
Delay is acceptable within float limits.
Project buffer absorbs the delay without shifting the final date.
Actions to take:
Recalculate the network diagram to assess the new critical path.
Adjust resources or re-sequence tasks to regain lost time.
Communicate changes clearly to ensure team alignment.
When Resources Are Reallocated
Resource availability can change due to staff illness, machinery failure, or budget shifts. Managers may need to redistribute limited resources, affecting timelines:
Activities with float may be paused or extended to free resources for critical tasks.
Reallocation can change task durations, requiring re-evaluation of start and end times.
May create new dependencies or remove existing ones, altering the project flow.
Result: The original critical path may change. Regular analysis ensures strategy remains viable and responsive.
When Project Scope Changes
Strategic implementation often faces changes in scope — whether due to stakeholder demands, budget changes, or competitor actions. This necessitates updates to the network diagram.
Scope changes may involve:
Adding new activities: Requires identification of dependencies and estimation of durations.
Removing activities: May reduce project length or shift the critical path.
Altering durations: May affect both float and dependency sequencing.
To maintain effective implementation:
The network diagram must be redrawn with new timelines.
Forward and backward passes must be conducted again to update float and path data.
Stakeholder communication is essential to manage expectations.
Value of Network Analysis
Network analysis provides a structured method for managing large or complex projects. Its benefits are wide-ranging and align closely with strategic success.
Helps Identify Priorities and Bottlenecks
Activities with zero float are clearly identified and prioritised.
Bottlenecks — where multiple activities depend on one task — can be spotted early and managed.
Supports effective delegation and monitoring of critical tasks.
Supports Resource Management
Highlights flexible activities, helping managers shift resources to areas of greatest need.
Enables balanced workloads, reducing burnout and improving efficiency.
Facilitates decisions on outsourcing, overtime, or fast-tracking specific tasks.
Encourages Realistic Time Planning
Projects are built on accurate estimations of time, based on dependencies and durations.
Promotes data-driven planning rather than overambitious or arbitrary deadlines.
Aids in the creation of contingency plans, especially in high-risk or uncertain projects.
Improves Team Communication and Accountability
The visual nature of network diagrams helps all team members see how their tasks fit into the whole project.
Helps prevent misunderstandings about deadlines and responsibilities.
Provides a basis for feedback and decision-making, especially when issues arise.
Aligns with Strategic Objectives
Ensures that project deadlines match market opportunities, regulatory windows, or organisational targets.
Helps leadership teams monitor progress and intervene before strategic failures occur.
Promotes a systematic approach to implementation, reducing reliance on guesswork.
Limitations of Network Analysis
Despite its advantages, network analysis has some limitations, especially when applied to dynamic or large-scale business environments.
Complexity in Large Projects
Diagrams can become too large and difficult to read, especially in projects with hundreds of activities.
Managing updates across complex interdependencies can be time-consuming.
May require specialist software or training to interpret effectively.
Assumes Certainty and Accuracy
Depends on accurate task duration estimates, which can be hard to achieve.
Incorrect assumptions about dependencies or times can mislead project managers.
Real-world factors like weather, supply chain issues, or political risks are hard to model.
Requires Regular Maintenance
Network diagrams need to be updated regularly to remain useful.
In fast-moving industries, this can be impractical or delayed, resulting in out-of-date plans.
Without active management, the analysis can give a false sense of control.
Overemphasis on Time Management
Network analysis focuses heavily on scheduling and not on:
Cost
Quality
Customer satisfaction
Employee wellbeing
Success in strategic implementation also depends on value creation, not just timely delivery.
FAQ
Yes, a project can have multiple critical paths if there is more than one sequence of activities with the same longest duration and zero float. This means the project is more exposed to risk, as delays on any of these paths will delay completion. It also makes the project harder to manage, as more tasks must be carefully monitored. Having multiple critical paths requires tighter control, more resource coordination, and can reduce the flexibility normally available through float in other tasks.
If a task not on the original critical path becomes delayed and uses up all its float, it can shift onto a newly formed critical path. This change means the original critical path is no longer the only determinant of the project timeline. Project managers must then reanalyse the network diagram to identify the new path and adjust resource allocation accordingly. This dynamic shift highlights the importance of regularly updating the project schedule to track evolving priorities.
Dependencies reduce scheduling flexibility by requiring one task to be completed before another can begin. The more dependencies a task has, the less float it is likely to have. This limits when and how tasks can be rescheduled or overlapped. In contrast, independent or loosely linked tasks offer more float and greater adaptability. A well-structured network diagram clearly displays these dependencies, allowing project managers to plan around constraints and identify which tasks have the most impact on timelines.
To reduce project duration without altering scope, businesses can use techniques such as crashing and fast-tracking. Crashing involves allocating additional resources to speed up critical tasks, such as using more staff or overtime. Fast-tracking means performing tasks in parallel that were initially planned to be sequential, provided dependencies allow it. These strategies may increase costs or risk but can shorten delivery time. The network diagram helps identify which activities can be targeted for these adjustments safely.
When a business runs multiple projects simultaneously, network analysis can help coordinate resources and minimise scheduling conflicts. By mapping out each project’s critical path and float, managers can identify overlaps in labour, equipment, or budget demands. It also supports prioritisation by showing which projects are more time-sensitive. This holistic view ensures that strategic goals are not compromised by internal competition for resources, enabling better alignment of timelines and more efficient portfolio management across departments.
Practice Questions
Explain the value of calculating total float when managing a strategic project. (6 marks)
Calculating total float allows managers to identify which tasks have scheduling flexibility and which must be prioritised. This helps allocate resources efficiently by focusing on critical tasks with zero float while using float time to manage delays elsewhere. It also supports proactive planning, helping managers adjust when unexpected issues arise without delaying the overall project. Understanding float enhances coordination across departments and aids in risk management by highlighting tasks that can be adjusted to optimise workflow, minimise idle time, and ensure strategic goals are met on time and within scope.
Analyse how network diagrams can support the successful implementation of business strategy. (9 marks)
Network diagrams visually map out project activities, showing their sequence, duration, and dependencies. This supports strategic implementation by helping managers plan timelines, identify the critical path, and allocate resources to essential tasks. By calculating float, businesses gain flexibility to adapt when delays occur without affecting deadlines. Diagrams also enhance communication by clearly displaying expectations across teams, improving coordination and accountability. As strategic goals often require timely execution, network diagrams offer a structured approach that increases efficiency and reduces the risk of failure. However, their usefulness depends on accurate data and frequent updates to reflect real-time conditions.
