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  • Address problems: in particular: resource constrained scheduling
  • Other definitions: the path with the least slack
  • DEMO use the file DEMO Perfect Critical Path.mpp; it will show a fragmented Critical Path and this will introduce that concept quite nicely!
  • Other issues:Estimates are future-oriented and have, by definition, a probalistic nature: Hidden Critical Paths Protecting the Critical Path
  • Other definitions considered:A constraint is any value entered into the schedule that affects the start and/or finish dates of activities. A constraint is something that should be respected by any scheduling algorithm. A constraint is a factor that limits the system from having more throughput (from the Theory of Constraints and Critical Chain Project Management).
  • Schedule data typically includes WBS, estimates, dependencies, resources, assignments, priorities and schedule constraints.
  • http://scheduleanalyzer.com/sa_long_theory.htm
  • We discussed hard about introducing new term of “Resource Total Float”; decided against it because it does not have meaning in non-resource constrained schedules. Also, total float would be useless in resource-constrained schedules.
  • Critical Path 3.0: may require that financial constraints are also taken into account
  • This view reveals: Who is Critical When?
  • This view reveals: Why is the Critical Path 2.0 what it is?
  • This example shows that CCP takes resource, date and calendar constraints into account!!
  • This is the “All-Paths algorithm”
  • POINT if you need to look at all logical paths as well as all resource paths, you end up with 1000’s of paths to calculate!! Each resource assignment is a path! In last path, “4, 3” is a resource dependency!
  • 111

    1. 1. Critical Path 2.0The Next Edition of the Critical Path TheorySoftware Specification for Critical Path 2.0Compliance Eric Uyttewaal, PMP ProjectPro Corp. www.ProjectProCorp.com
    2. 2. Presenter Intro: Eric Uyttewaal, PMP  President ProjectPro Corp.  Specializes in Microsoft Project and Project Server  BS, Engineering; MS Business Administration  Author “Forecast Scheduling with Project 2010” and “Dynamic Scheduling with Microsoft Office Project 2003”  Formerly: Executive Director at IIL as developer and manager of the Orange, Blue, Black Belt certification curriculum  Email: EricU@ProjectProCorp.com  Tel: 613-692-7778
    3. 3. Consulting by ProjectPro: Specialties1. Project Server 2007/2010 Implementations2. Scheduling of Programs (with many links between subprojects)3. Schedule improvement and raising scheduling maturity © ProjectPro Corp.
    4. 4. Members of the Working GroupRobyn Antill Sai PrasadMichelle Colodzin Wayne RobinsonBrian Evans John KrahulaTimothy Mather Gary HartnettFernando Nunes de Oliveira Vladimir LiberzonRaul Römer Jack DahlgrenMurali Puthiyarambath Charles FollinJohn Stiles Eric UyttewaalAli Vessali © ProjectPro Corp.
    5. 5. Objectives of the Working Group Improve Critical Path Theory – Address problems experienced in practice Develop Critical Path 2.0 Theory – No “best practices” Elevate entire field of scheduling software Publish paper at PMI-SCOP (PMI-COS) conference in May 2011 © ProjectPro Corp.
    6. 6. Critical Path 1.0Critical Path 1.0 (CPM 1.0) was first defined by: Kelley, James. Critical Path Planning and Scheduling: Mathematical Basis. Operations Research, Vol. 9, No. 3, May-June, 1961 Critical-Path Planning and Scheduling, Kelley, James E. Jr., and Walker, Morgan R., Proceeding of the Eastern Joint Computer Conference, Boston. December 1-3, 1959, pp. 160-173. 10. © ProjectPro Corp.
    7. 7. Critical Path 1.0 DefinitionGenerally, but not always, the sequence ofschedule activities that determines the durationof the project. It is the longest path through theproject.Source: PMBOK (4th Edition) ©ProjectPro Corp.
    8. 8. Assumptions of Critical Path 1.01. Activity estimates are normally distributed PERT or Monte Carlo Simulation2. There is no merge-bias or path-convergence Monte Carlo Simulation3. You have unlimited resources available Critical Chain, Resource Critical Path and Simulation © ProjectPro Corp.
    9. 9. “Activity is Critical when Total Float <=0” leads to: Software displays too many critical tasks: Software displays too few critical tasks: Parts of the Critical Path ©ProjectPro Corp.
    10. 10. Scheduling Software DisplaysToo Few Critical Tasks when: Incomplete network logic Constraint Dates Elapsed Durations and Elapsed Lags Resource Calendar: Unavailability of Resources Task Calendars External Predecessors Workload Leveling © ProjectPro Corp.
    11. 11. DEMO Incomplete Critical Path Use: DEMO Perfect Critical Path.mpp ©ProjectPro Corp.
    12. 12. How Leveling Affects the Critical Path 1.0Write X Harry 3 D OptimisticWrite Y Harry 2 D Forecasts levelingWrite X Harry 3 D IncompleteWrite Y Harry 2 D Critical Path © ProjectPro Corp.
    13. 13. Resource Dependencies Differ fromLogical DependenciesA logical dependency imposes the sequence: Write PrintA resource dependency does not impose sequence. Therelationship is that both tasks share the same resource.Write X Harry Write X Harry ORWrite Y Harry Write Y HarrySource: Forecast Scheduling with Microsoft Project 2010 © ProjectPro Corp.
    14. 14. Summary: Issues with Critical Path 1.0 Weak definition: it contains literally “Generally, but not always…”. PMBOK 4th edition Critical Path 1.0 assumptions are no longer tenable Critical Path 1.0 cannot handle date, calendar and resource constraints. Problems: – Incomplete Critical Paths – No Resource-Critical Paths © ProjectPro Corp.
    15. 15. Introduction of Terminology forCritical Path 2.0 Schedule Schedule Data Constraints Project Schedule Project Scheduling Application
    16. 16. Project Schedule Data WBS Constraints: Estimates  Logical constraints Dependencies  Resource availability constraints Resources: Materials, Machines,  Date constraints Labor, Facilities, Land, Three-  Calendar constraints: Project, Dimensional Space Resource, Activity, Lag/Lead Priorities: Project, Deliverable/Activity, Resource  Financial constraints Constraints (see next column)  Physical constraints  Organization policy constraints  Regulatory or Legal constraints  Ecological constraints  Political constraints © ProjectPro Corp.
    17. 17. Constraints: DefinitionConstraints are a special type of project schedule datathat the scheduler needs to take into account in orderto produce a realistic and feasible schedule.Source: Proceedings of Critical Path 2.0 working group, Mar. 2011 © ProjectPro Corp.
    18. 18. Critical Path 2.0 DefinitionThe Critical Path 2.0 is the subset of activities thatdetermines and explains the entire duration of the schedulewhen all schedule data that are entered into the schedulingapplication are taken into account.There can be more than one Critical Path that run in parallelin a schedule.Source: Proceedings of Critical Path 2.0 working group, Mar. 2011 ©ProjectPro Corp.
    19. 19. Term “Subset” Path – The word is in the term to define – Implies logical links (resource dependencies?) Chain – Implies logical links Series – Implies logical links Subset: – Reveals added value of the theory: focus! © ProjectPro Corp.
    20. 20. Term “Longest Path”Longest Path = the string of directly related activitiesthat comprise the longest path from the data date tothe last activity in the schedule (Source: Ron Winter) Deals effectively with most constraints mentioned except with resource constraints Does not deal well with a situation where a few, short activities start from a start-no-earlier-than constraint that finish later than any other path © ProjectPro Corp.
    21. 21. Term “Total Float” Critical Path 1.0 (PMBOK 4th edition): The total amount of time a schedule activity may be delayed from its early start date without delaying the project finish date, or violating a schedule constraint. Critical Path 2.0: The total amount of time a schedule activity may be delayed from its early start date without delaying the project finish date, or violating any schedule constraint (including resource constraints) based on the current schedule. © ProjectPro Corp.
    22. 22. “…based on the current schedule”A necessary stipulation when calculating the Critical Path 2.0 inresource-constrained schedules: Write X Harry Write X Harry OR Write Y Harry Write Y Harry OR Write X Harry Over-allocation; resource constraint Write Y Harry violated! © ProjectPro Corp.
    23. 23. The Differences between Critical Path 1.0 and Critical Path 2.0  Critical Path 2.0 applies in resource-constrained schedules  Critical Path 2.0 standard requires that (at least) the next four schedule constraints should be taken into account: logical, resource, date and calendar constraints  Critical Path 2.0 always produces a complete Critical Path when these constraints are used in schedules  You can end up with a different Critical Path under Critical Path Method 2.0 than you would under Critical Path Method 1.0. Critical Path 2.0 compliant scheduling software must:be able to deal with logical, resource, date and calendar constraints, and produce a complete Critical Path when those constraints are used © ProjectPro Corp.
    24. 24. Critical Path 1.0: How a Date- andCalendar-Constrained Schedule Looks 1 of 2 An Incomplete Critical Path © ProjectPro Corp.
    25. 25. Critical Path 2.0: How It Could Look“Complete Critical Paths 2.0” from www.ProjectProCorp.com 2 of 2 A Complete Path with Gaps Explained © ProjectPro Corp.
    26. 26. Critical Path 1.0: How a Resource-Constrained Schedule Looks Gaps in the Critical Path 1.0 © ProjectPro Corp.
    27. 27. Critical Path 2.0: How It Could Look“Complete Critical Paths 2.0” from www.ProjectProCorp.com 1 of 3 Complete Path that Reveals Who is Critical When © ProjectPro Corp.
    28. 28. Critical Path 2.0: How It Could Look“Complete Critical Paths 2.0” from www.ProjectProCorp.com 2 of 3 Complete Path Explained to You © ProjectPro Corp.
    29. 29. Critical Path 2.0: How It Could Look“Complete Critical Paths 2.0” from www.ProjectProCorp.com 3 of 3 Complete Path even with Date, Calendar and Resource Constraints © ProjectPro Corp.
    30. 30. How to Find the Critical Path 2.0 inResource-Constrained Schedules? 1 of 21. List all activities and enter all effort estimates2. Determine all relationships including type of dependency (FS, SS, FF and SF) and lags (or leads)3. Enter all resources and their resource calendars4. Assign resources to the activities and allocate the effort5. Determine the duration of each activity6. Enter all other constraints: date and calendar constraints7. Level the workloads of all resources completely.8. Determine all possible paths of the logical dependencies and resource dependencies9. Determine the duration of each path through the network taking all logical dependencies, resource dependencies and all other constraints into account.10. Identify the longest path(s) of all possible paths that explain the entire project duration; this is Critical Path 2.0. © ProjectPro Corp.
    31. 31. How to Find the Critical Path 2.0 -Example Paths Duration path 2, 3, 5, 6 2+4+2+2=10 path 2, 4, 5, 6 2+5+2+2=11 path 2, 4, 3, 5, 6 2+5+4+2+2=15 © ProjectPro Corp.
    32. 32. How to Find the Critical Path 2.0 inResource-Constrained Schedules? 2 of 2 Mark the project finish milestone Mark the resource-critical task(s) and analyze each separately Do logical and/or Yes resource dependencies drive it to this date? No Do other causes Yes than the project start date Find the next RCP task drive it to this date? No All resource-critical tasks marked © ProjectPro Corp.
    33. 33. Software Specification forCritical Path 2.0 Compliant Software1. Is able to capture logical, resource, date and calendar constraints2. Will alert the user to incomplete network logic3. Will alert the user to over-allocations4. Is able to level the workloads in the schedule5. Is able to produce a complete Critical Path that explains the entire project duration when those constraints are used © ProjectPro Corp.
    34. 34. Thank You for Attending ! Discuss with professional schedulers online: LinkedIn group “Forecast Scheduling” To receive a PDF-file of the Critical Path 2.0 paper, email: EricU@ProjectProCorp.com

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