1.3 - Critical Path Analysis
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Understanding the Network Diagram
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Today, we're going to explore the project network diagram. Can anyone tell me how we represent activity durations in this diagram?
I think we write the activity letter and its duration together.
Correct! We write the activity letter followed by the duration. So, if we look at activity A, it says A8, meaning activity A has a duration of 8. Now, what's unique about the numbers above and below the arrows?
The numbers above tell us when the activity can start and finish earliest, and the ones below denote the latest times?
Exactly! This helps us understand both the earliest and latest start times for activities. Can anyone define what float is?
I think it's how much we can delay an activity without impacting the overall project timeline.
Right! Float is the flexibility we have in scheduling activities. Well done, everyone!
Identifying Critical Path Activities
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Now that we know the definitions, let’s identify critical activities. What is meant by the critical path?
I believe it's the longest path in a project that determines how long the project will take overall.
Exactly! For our example, we determined that activities B, E, and I form the critical path, taking 20 days total. What happens if one of these activities is delayed?
The whole project will be delayed too, since they're critical!
Absolutely, activities on the critical path have no float. They are essential to keeping the project on schedule. Now, let’s discuss resource constraints. What resources do we have to manage in this project?
We only have two cranes available.
Good! That limited resource will indeed impact our scheduling.
Resource Allocation Strategies
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Given our resource constraint of two cranes, how should we allocate them?
I think we should give them to the activities with the least float first, the critical ones.
Exactly! By focusing on those with zero float, we can minimize delays. Can you give me an example of how this allocation begins?
Sure! We would give one crane to activity B first since it has zero float.
Great! And once B is completed, what should we consider for the next allocation?
We should look for the next eligible activities, focusing on the ones that are critical or have the least float.
Exactly! This prioritizes project efficiency.
Impact of Resource Constraints on Project Timeline
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Now that we've explored our resource allocation technique, what do you think the impact of two cranes might be on our project timeline?
Well, if we're constantly waiting for resources, the project will probably take longer.
Right! Based on our planning, the initial duration is 20 days but how does the resource constraint change that?
I think it pushes the timeline to 29 days.
Exactly! This shows how managing resources under constraints can affect overall completion. It's crucial to keep project delays to a minimum through smart planning!
So, focusing on critical activities really helps in managing these constraints.
Indeed! Great understanding!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
The section explores critical path analysis by detailing how activity durations are used to determine project timelines. It emphasizes the significance of float, critical activities, and resource constraints in project management. A common approach for resource allocation—least total float—is discussed in relation to achieving project goals efficiently.
Detailed
Detailed Summary
Critical Path Analysis (CPA) is a vital technique in project management, allowing project managers to understand which activities are most crucial to the project's timeline. In this section, we explore how to construct a project network diagram to depict activities (A to K) and their durations. Essential concepts include:
- Activity Duration: Each activity's duration affects how soon it can start (earliest start time) and how late it can start without delaying the entire project (latest start time).
- The difference between these times is known as the float. An activity with zero float is deemed critical and can lead to project delays if not managed properly.
- Resource Allocation: The discussion transitions to resource allocation, especially when resources are constrained (in this case, the number of cranes available). Initially assuming unlimited resources, the project duration is calculated at 20 days. However, with only two cranes available, resource allocation becomes key to minimizing delay.
- The least total float approach prioritizes assigning resources to activities with the least float, consequently allocating cranes first to critical activities.
- Project Reevaluation: Following optimal resource allocation, delays due to resource constraints may increase project completion to 29 days. Project managers must balance resource limitations while striving to keep project delays within acceptable limits.
This section closes with a summary of resource allocation strategies and emphasizes the critical path's role in navigating project completion amidst resource constraints.
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Understanding Activity Durations
Chapter 1 of 6
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So, the activity duration is represented here as you can see A refers to the activity and 8 refers to the activity duration. So, above the arrow, you can see the numbers are indicating the earliest start time earliest finish time and below the arrow the numbers are indicating the latest start time and later finish time of the particular activity.
Detailed Explanation
In project management, each activity has a defined duration, which is the amount of time required to complete that activity. For example, if Activity A takes 8 days, it means that if started at its earliest time, it will end after 8 days. Additionally, we track specific time indicators for each activity. Above each arrow in a project network diagram, we note the earliest start time (the soonest an activity can begin) and earliest finish time (when it would complete if started immediately). Conversely, below the arrow, we list the latest start time (the latest it can begin without delaying the project) and latest finish time (when it must be completed to keep the project on schedule).
Examples & Analogies
Think of it like planning a road trip. You know how long it takes to drive from point A to B (the activity duration). You could leave as early as 8 AM to avoid traffic (earliest start time), or you could leave later, say at 10 AM, but then you have to rush to arrive on time (latest start time). If your trip is scheduled for a specific arrival at 5 PM, knowing these times helps you plan your stops and ensure you reach your destination on schedule.
Defining Float in Activities
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So, earliest start time is how early an activity can be started. And later start time is how delayed an activity can be started without affecting the project completion time. So, that means this particular activity A it can start can be delayed by 3 days, but this one affect the project completion time. So this has a float of 3 days.
Detailed Explanation
Float, or total float, refers to the amount of time an activity can be delayed without delaying the overall project completion. For instance, if Activity A has a float of 3 days, it means that even if Activity A starts 3 days later than planned, the project will still finish on the scheduled date. This is useful for resource planning as it allows project managers to prioritize which activities may be postponed without jeopardizing timelines.
Examples & Analogies
Consider a school project that has a deadline. If you learn you can push back the start of your research by three days without affecting your final submission date, that three days is your float. It gives you room to manage other tasks or unforeseen issues that could arise, just like a buffer in your schedule.
Identifying the Critical Path
Chapter 3 of 6
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So, the critical part of this project is B, E and I, the critical path is nothing but the longest path in a particular project which decides the project completion time. So, for this project, that the critical path is B, E, I and its duration is 20 days.
Detailed Explanation
The critical path consists of activities that directly impact the project's completion time. In our example, Activities B, E, and I form the critical path, totaling 20 days. If any of these activities are delayed, the entire project will be delayed. Non-critical activities have float and can be delayed without impacting the project schedule. Identifying this path helps project managers focus their resources and attention on activities that are critical for timely project delivery.
Examples & Analogies
Think of this like a relay race where certain runners (activities) must finish before others can start. If the runner for leg B (first critical activity) slows down, the whole team is delayed, just as if any activity on the critical path is delayed, the project's deadline is pushed back.
Resource Allocation Challenges
Chapter 4 of 6
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So, there will be always a limitation for the resource. So, first it is drawn assuming that it is unlimited. And now the project completion time you can see it is 20 days. So, this project is getting completed in 20 days, if you assume there is no constraint on resources.
Detailed Explanation
In reality, projects often face resource constraints, meaning there are limits on the availability of materials, equipment, and manpower. Initially, the project is planned as if resources are unlimited, resulting in a straightforward completion time. However, once resources like cranes become limited, the actual project timeline may change, highlighting the importance of adjusting plans to reflect achievable timelines based on available resources.
Examples & Analogies
Imagine planning a picnic. If you assume you have access to as many sandwiches and drinks as you want, you can invite as many friends as you want. However, once you learn that you only have enough sandwiches for two friends, you'll have to adjust your plans to make sure everyone gets fed, which might mean having a smaller picnic or finding other ways to provide food.
Allocating Resources to Critical Activities
Chapter 5 of 6
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So, we are trying to identify the activities which are more critical. So, whichever activities have least total float, those activities are more critical, I mean, as I told you, the activities which have 0 float, they are called as critical.
Detailed Explanation
When allocating limited resources like cranes, project managers prioritize activities based on their float. Activities with the least float are considered most critical and should receive resources first to ensure timely completion. By focusing on critical activities (which have zero float), managers help prevent delays in the overall project timeline.
Examples & Analogies
Think of a fast-paced kitchen where multiple chefs work on different dishes. The chef in charge might prioritize dishes that take longer to cook (critical) so that they are ready for serving on time, rather than focusing on side items that can wait, ensuring that the meal is completed promptly.
Using an Equipment Loading Chart
Chapter 6 of 6
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So, this is called the equipment loading chart. So, by looking at this equipment loading chart, you can see that the equipment is utilized in a very effective way there is no idle time for the machine.
Detailed Explanation
An equipment loading chart visually represents how and when equipment is being used throughout the project lifespan. Effective utilization is critical to minimize idle time, ensuring that machinery is operating at capacity as much as possible. This chart helps project managers to schedule usage of resources intelligently, aligning it with project timelines and task completion.
Examples & Analogies
Imagine a busy construction site where cranes are scheduled to lift materials at specific times. If a crane sits idle all day, that's wasted time and money. The equipment loading chart acts like an optimized schedule for a DJ at a party, ensuring the music starts and stops at the right moments to keep the dance floor active and avoid awkward silences.
Key Concepts
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Activity Duration: The time required to complete a task.
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Earliest Start Time: The soonest an activity can begin.
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Latest Start Time: The latest an activity can begin without delaying the project.
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Float: Time that a task can be delayed without impacting project completion.
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Critical Path: The sequence of activities that determines the project completion time.
Examples & Applications
Consider two activities: A with a duration of 3 days and B with a duration of 5 days. If A must be completed before B can start, then A is on the critical path if there is no slack time.
In a project with four activities requiring a crane, if only two are available, you must allocate the cranes prioritizing the critical activities first.
Memory Aids
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Rhymes
Float can be great, don’t wait; Miss the deadline, don't hesitate.
Stories
Imagine building a tower. You have scaffolding (activities) and can work on two sections at a time (resources). If you delay a critical section, the entire tower project won't finish on time.
Memory Tools
Use C for Critical Path, F for Float, and R for Resource Allocation - C-F-R!
Acronyms
Use F.A.C.E.. F for Float, A for Allocation, C for Completion Time, E for Early Start.
Flash Cards
Glossary
- Critical Path
The longest path in a project that determines the shortest time to complete the project.
- Float
The amount of time that you can delay a task without delaying the project.
- Resource Allocation
The process of assigning available resources in an efficient manner.
- Network Diagram
A visual representation of the project tasks and their dependencies.
- Activity Duration
The time required to complete a specific task in a project.
Reference links
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