Bpp 3213 lecture 2
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The document provides an overview of network scheduling and the precedence diagram method (PDM) for project scheduling. It discusses the brief history of scheduling techniques including Gantt charts, arrow diagrams, critical path method (CPM), and program evaluation and review technique (PERT). It also covers the purpose of project scheduling, the schedule development process, logic diagrams and networks, critical path analysis, precedence diagram method (PDM), and key scheduling terms.
Bpp 3213 lecture 2
- 1. BPP 3213 PROJECT ESTIMATION AND SCHEDULING Lecture 2 Network Scheduling and Precedence Diagram Method (PDM) Oct, 2012 Faculty of Technology Universiti Malaysia Pahang Jane Doe & Jane Doe
- 2. RECAP Organization Structure Challenges Project life cycle
- 3. Purpose of this lecture To better understand: • brief history of scheduling techniques • network scheduling and logic diagrams • the importance of Critical Path Method (CPM) • the fundamental elements of precedence diagram method (PDM)
- 4. Scheduling is for everyone it is a discipline that is performed by every person, every day. Scheduling is an application of special knowledge or judgment of the mathematical , physical, or engineering sciences to the conception or implementation of creative work.
- 5. The History
- 6. Brief History Gantt Charts / Bar Charts History Advantage Drawback Until 1958, the only tool Simple to construct and difficult to determine the for project scheduling read impact of slip on one task was a bar chart on the rest of the project Henry Gantt had developed a complete notational system showing progress with bar chart, thus they called Gantt charts
- 7. Brief History (cont’d) Arrow Diagrams History Advantage Drawback Late 1950s and early An arrow diagram Tend to be too 1960s, two methods help the team complicated for of scheduling were understand the some teams developed to interdependencies of capture the the tasks sequential and parallel relationships among project activities
- 8. Brief History (cont’d) Critical Path Method (CPM) History Advantages Drawbacks Developed by Du Pont in Graphical view of the CPM can be complicated, 1957 project and complexity increases for larger projects Initially to address the Predicts the time required challenge of shutting down for the project Does not handling the chemical plants for scheduling of personnel and maintenance and restarting Shows which activities are resource allocation it again once maintenance critical to maintain the completed schedule and which are not Not always clear and need to be calculated carefully Utilizes the planner’s knowledge, experience, and Estimating activity instincts in a logical way completion times can be difficult
- 9. Brief History (cont’d) Program Evaluation and Review Technique (PERT) History Advantages Drawbacks Developed by US Navy It allows for Complicated chart and Booze, Allen and randomness in activity Hamilton at late 1950’s completion times Prediction inaccuracies Has potential of reducing both time and cost required to complete the project
- 12. Purpose of Schedule • Schedules are tool to : Communicate time Assess time plan plan
- 13. Purpose of Schedule (cont’d) Benefits: - Identify the timeframe - Identify the resource requirement - identify the key milestones - Identify the key stakeholder engagement points - Assess impact of resource constraints - Determine your commitment and obstacles
- 14. Schedule Development Process Network-logic Estimates - times Project Scheduling Schedule Resource capability Resource capacity
- 17. Your New Tool •Defacto standard for scheduling software in construction industry has been Primavera Project Planner aka P3 •In 2000, P3 has improved for the use by manufacturing and IT industries
- 18. Your New Tool (cont’d) •Major differences that distinguish one software system from another are •Ease of input •Ease and variety of means of reporting output •Features that permit the user to get around some of the limitation of the math upon which CPM is founded to more perfectly model the real world
- 19. Logic Diagrams and Networks • Effective project plan – address equally the parameters and activity logic • Illustrate the inductive and deductive reasoning to achieve objectives within time given • Constructed similarly to bar charts – supposing nothing will go wrong • Normally accompanied by detailed questions/checklist
- 20. The Logic of the Logic Diagrams • backbone of traditional implementation of CPM is graphical model of a project •Basic component is the arrow •Each arrow represents one activity in a project activity start finish
- 22. The Critical Path • The longest path throughout a project network • Has no slack (or float) therefore all activities on the critical path must be completed as scheduled • End date will begin to slip – one day for each day a critical activity is delayed
- 23. The Critical Path (cont’d) • Originally, the critical path considered only logical dependencies between terminal elements •Since then, it has been expanded to allow for the inclusion of resources related to each activity , through processes called activity-based resource assignments and resource leveling
- 24. What is CPM really?
- 25. The Critical Path (cont’d) • Also known as Critical Path Analysis (CPA) – is a mathematically base algorithm for scheduling a set of project activities • An important tool for effective project management • Commonly used with all forms of projects including construction, software development, research projects, product development, engineering, and plant maintenance among others
- 26. The Critical Path (cont’d) • Essentially, to construct a model for a project, we need: WBS Time (duration) Dependencies
- 27. Terms you have to get used to... • Event: equivalent to a milestone – indicate the start and finish dates • Activity: element of work that must be accomplished • Duration: total time required • Effort: amount of work actually performed within the duration
- 28. Calender Scheduling • Calendar unit: - Time measurement for project schedule - The smallest unit of time - In hours, days, or weeks, years, months, shifts, even in minutes • Take into account for issues such as: - For non-working time (weekend, holidays) - Resource constraint - Change risk - Cash flow - Logistics
- 29. Precedence Diagram Method (PDM) • Visual representation technique • Depicts the activities involved in a project • Also known as Project Network Diagrams • PDM helps: - Communicate - Identify missing activities - Identify critical activities - Create project schedule
- 30. Precedence Diagram Method (PDM) (cont’d) •Types of Dependencies: - Finish to Start (FS) : the predecessor must be completed before the successor can start Predecessor FS Successor 10 days 5 days Start Day: 1 Start Day: 10 Finish Day: 10 Finish Day: Start Day + 5
- 31. Precedence Diagram Method (PDM) (cont’d) •Types of Dependencies: - Start to Start (SS) : the successor can start at the earliest after the start of its immediate predecessor Predecessor 10 days SS Successor 5 days Start Day: 1 Start Day: 1 Finish Day: 10 Finish Day: 5 days after start day
- 32. Precedence Diagram Method (PDM) (cont’d) •Types of Dependencies: -Finish-Finish (FF): the successor will finish at the latest after its predecessor finished Predecessor 10 days FF Successor 5 days Start Day: 1 Finish Day: 10 Finish Day: 10 Start Day: 5 days before finish day
- 33. Precedence Diagram Method (PDM) (cont’d) •Types of Dependencies: -Start-Finish (SF) : the successor can finish only after the predecessor has started Predecessor 10 days SF Successor 5 days
- 34. Precedence Diagram Method (PDM) (cont’d) Multiple PDM Relationships: • Two PDM dependencies/relationships can be used together – combination • Having both SS and FF relationships in one activity SS =5 15 15 • B must be finished not later than 10 Activity A Activity B days after A is finished and starts after 5 days A started i.e. starts at day 10 FF=10
- 35. Precedence Diagram Method (PDM) (cont’d) Lag Time: • It’s a technique • Occurs when you add time to the start or finish of predecessor task • Causes a gap in timing • E.g.: FS dependency with 5 days lag = the successor cannot start until 5 days the predecessor has finished
- 36. Precedence Diagram Method (PDM) (cont’d) Lead Time: • It’s also a technique • Created when you subtract time from the start or finish of predecessor task • Causes overlap between two tasks • Allow acceleration of the successor activity • E.g.: FS dependency with 5 days lead= the successor can start 5 days before the predecessor has finished
- 37. Level of Detail • Should never have too little nor too much detail • Logical structure with appropriate level of detail is the key to tracking throughout the project • Contents information required to manage the project – only that information • Rule of thumb: - 80 hour rule - if it make sense
- 38. Conventional Assumptions • Activity duration – scheduling done based on expected or most likely time duration for each activity • Contingency allowance for activity duration • Availability of resources • Schedules to have low cost or ideally lowest cost
- 39. Summary •Network scheduling and PDM are techniques to assist PM in scheduling – translating project brief into time schedule
- 40. Questions??? He who ask is a fool for five minutes, but he who does not ask is a fool forever.
Editor's Notes
- #7: Scheduling is a tool used to manage jobs and should not be considered as the primary one in project management. Project management is not just about schedulingGantt charts remain the best tool to use for communicating to team members about what they need to do within given time framesBar charts do not show the interdependencies of the work thus the serious drawback.PERT methods use probability techniques, whereas CPM does not. Meaning: PERT enable PM to calculate the probability that an activity will be completed by a certain time whereas CPM unable to do that.
- #13: Communicating tool: putting project brief into schedules against timeAssess time plan: possibilities of delay e.g. client sign off, force majeure Resource constraint: availability of people (on leave??), availability of plants/machines (set priority if sharing plants and machines with other project)Determine your commitment: make sure we have enough time to resolve the issues in the schedule
- #14: Communicating tool: putting project brief into schedules against timeAssess time plan: possibilities of delay e.g. client sign off, force majeure Resource constraint: availability of people (on leave??), availability of plants/machines (set priority if sharing plants and machines with other project)Determine your commitment: make sure we have enough time to resolve the issues in the schedule
- #15: The network provides the logic for the order in which activities need to be carried outTime estimates show the time that the project requires for completionResource capability is the set of tasks that the resources available to the project manager can reasonably undertake. Often referred to as resource pool.Resource capacity depends on the volume of resources available and issues such as resource calendar. E.g. machine utilisation is not to be taken into the same consideration with human.
- #18: Gantt chart becomes cluttered when the number of activities and logical relationship increase inductive reasoning takes events and make generalizationsdeductive reasoning arrives at specific conclusion based on generalization
- #19: Gantt chart becomes cluttered when the number of activities and logical relationship increase inductive reasoning takes events and make generalizationsdeductive reasoning arrives at specific conclusion based on generalization
- #20: Gantt chart becomes cluttered when the number of activities and logical relationship increase inductive reasoning takes events and make generalizationsdeductive reasoning arrives at specific conclusion based on generalization
- #21: Gantt chart becomes cluttered when the number of activities and logical relationship increase inductive reasoning takes events and make generalizationsdeductive reasoning arrives at specific conclusion based on generalization
- #23: Slack time: time differential between the scheduled completion date and the required date to meet critical pathSlack: the difference between the latest allowable date and the earliest expected date. Allowable deviation between when an activity must take place at the latest and when it can take place at the earliest LS-ES, LF-EF
- #31: Finish-Start is the most commonly used dependencyDefault setting for MS Project
- #32: Finish-Start is the most commonly used dependency
- #34: The predecessor is the task that determines the scheduling for the successorUsed to determine the task prior to but dependent on another taske.g: new theatre building n selling ticket tasks