Introducing the Relationship Diagramming Introducing the Relationship Diagramming Method Variant of

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  • Introducing the

    Relationship Diagramming Method Variant of the Critical Path Method of Planning & Scheduling Analysis

    Fredric L. Plotnick, Esq., P.E. Engineering & Property Management Consultants, Inc. Benson Manor #117 – 101 Washington Lane – Jenkintown, PA 19046

    www.fplotnick.com fplotnick@fplotnick.com 215-885-3733

    http://www.fplotnick.com/ mailto:fplotnick@fplotnick.com

  • • RECENT DEVELOPMENTS highlighted in the professional and technical societies and in academia, relating to the field of CPM Planning and Scheduling, have drawn attention to the focus upon information relating to individual and groups of activities and the lack of focus upon the relationships between these activities that was the hallmark of the original ADM and PERT methodologies

  • Gantt Charts are Easy to Read

  • But if you want to make even a small change...

  • ...to the duration of one activity ... you have a great deal of work to perform to determine the impact

    ??

  • CPM requires you to record the relationships between activities ...

  • ... and allows the computer to recalculate the impact of changes made ...

  • ... reducing the 40%+ rework effort to that of a keystroke

  • Logic Network Based Methods

    • CPM – Critical Path Method – 1956 E. I. du Pont de Nemours Company, Newark DE – and later known as

    • ADM = Arrow Diagramming Method – or as AOA = Activity on Arrow • PERT – Program Evaluation Review Technique

    – 1958 Special Projects Office of the Navy Bureau of Ordinance – for Research and Development of the Polaris Missile Program – also known as the Program Evaluation Research Task method

    • PDM – Precedence Diagramming Method – 1964 IBM implementation for H.B. Zachry Co. – and also known as AON = Activity on Node

    http://en.wikipedia.org/wiki/Image:Uss_george_washington.jpg

  • CPM

    http://www.amazon.com/exec/obidos/ASIN/0071344403/qid=957662118/sr=1-2/102-3541701-1708038

  • ADM K.I.S.S.

    Activity Descriptioni jduration of

    activityES EF LS LF__ TF

    __ TF

    TE = = TL

  • PERT

    logic onlyEvent #1 Description duration

    between eventsTETL

    TE TL__ TF

    __ TF

    Event #2 Description

  • PDM? Activity Descriptioni jduration of

    activity

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    ES=TEi LS≥TLi__

    TF __ TF

    EF≤TEj LF=TLj

  • PDM

    Activityi jduration of activity

    ES EF LS LF__ TF

    __ TF

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    issues with proper usage of non- traditional restraints

    A 10

    C 10

    SS 5

    A

    B

    B 10 FF 5

    need never finish

    C may start anytime

    C may start before NTP A is not required for project completion

    visible open ends hidden open ends

  • PDM

    Activityi jduration of activity

    ES EF LS LF__ TF

    __ TF

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    issues with continuous versus

    interruptible activities

    continuous duration interruptible duration

    A 20

    B 10

    FF5

    SS5

    A 20

    B 10

    FF5

    SS5

    SS5 SS5

  • PDM

    Activityi jduration of activity

    ES EF LS LF__ TF

    __ TF

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    issues with an activity based methodology

    Drywall 10

    Elect 5 PS2 FR2

    Drywall 10

    Elect 5 SS2 FF2

    Loop Error Detected

    activity A to activity B to activity A loop event 1 to event 2 no loop

  • PDM

    Activityi jduration of activity

    ES EF LS LF__ TF

    __ TF

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    A OD=10 3 RD=3

    B 10

    Seven days complete Seven days passed

    SS7 Calculated early start of activity B desired when A is 70% complete

    A OD=10 5 RD=5

    B 10

    Five days complete Seven days passed

    SS7 Activity A starts on time but loses two days in first week Calculated early start of activity B is two days early – when A is 50% complete

    issues with measuring from start versus from

    partial performance

    passage versus progress

  • PDM

    Activityi jduration of activity

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    partial-to-start partial-to-finish

    finish-to-remainder start-to-remainder

    ES=TE LS≤TL__

    TF

    TE TL__ TF

    TE TL__ TF

    EF≤TE LF=TL__

    TF

    “… but what we meant to say …”

    passage versus progress

  • PDM

    • start B 7 days after A has started • start B when 7 days of A are complete • start B when 70% of A is complete • start B when 35cy of 50cy is excavated

    • finish B 4 days after A is finished • finish last 4 days of B after A is finished • finish last 40% of B after A is finished • finish last 20cy of 50cy after A is finished

    Activityi jduration of activity

    finish-to-start start-to-start

    finish-to-finish start-to-finish

    start-to-start start-to-finish

    finish-to-start finish-to-finish

    duration between activities

    logic only

    partial-to-start partial-to-finish

    finish-to-remainder start-to-remainder

    ES=TE LS≤TL__

    TF

    TE TL__ TF

    TE TL__ TF

    EF≤TE LF=TL__

    TF

    “… but what we wanted to say …”

    passage versus progress

  • Notice to Proceed 0

    Foundation Excavation 5

    North FDN Form 6

    South FDN Form 6

    North FDN Strip 1

    East FDN Form 6

    East FDN Rebar 2

    East FDN Pour 1

    East FDN Strip 1

    North FDN Pour 1

    South FDN Pour 1

    West FDN Pour 1

    South FDN Strip 1

    West FDN Strip 1

    Foundation Backfill 2

    FS 2FS 2 FS 2 FS 2

    North FDN Rebar 2

    West FDN Form 6

    South FDN Rebar 2

    West FDN Rebar 2

    Resources

    Scheduling Resources is Not CPM

  • What can we do? • Maths of 50s watered down to 50s computers • PCs provide tools (but not skills) to the masses • More powerful PCs benefit glitz – not maths • GUI and WYSIWYG i/o favors bar charting • Wizards further reduce need for skills • Where is the logic?

  • Notice to Proceed

    0

    Foundation Excavation

    5

    North FDN Form

    6

    North FDN Rebar

    2

    North FDN Pour

    1

    North FDN Cure

    2

    North FDN Strip

    1 East FDN Form

    6

    East FDN Rebar

    2

    East FDN Pour

    1

    East FDN Cure

    2

    East FDN Strip

    1 South FDN Form

    6

    South FDN Rebar

    2

    South FDN Pour

    1

    South FDN Cure

    2

    South FDN Strip

    1 West FDN Form

    6

    West FDN Rebar

    2

    West FDN Pour

    1

    West FDN Cure

    2

    West FDN Strip

    1

    Foundation Backfill

    2

    Plan – then Schedule

    Notice to Proceed 0

    Foundation Excavation 5

    North FDN Form 6

    North FDN Rebar 2

    North FDN Pour 1

    North FDN Strip 1

    East FDN Form 6

    East FDN Rebar 2

    East FDN Pour 1

    East FDN Strip 1

    South FDN Form 6

    South FDN Rebar 2

    South FDN Pour 1

    South FDN Strip 1

    West FDN Form 6

    West FDN Rebar 2

    West FDN Pour 1

    West FDN Strip 1

    Foundation Backfill 2

    FS 2

    FS 2

    FS 2

    FS 2

  • Notice to Proceed

    0

    Foundation Excavation

    5

    North FDN Form

    6

    North FDN Rebar

    2

    North FDN Pour

    1

    North FDN Cure

    2

    North FDN Strip

    1 East FDN Form

    6

    East FDN Rebar

    2

    East FDN Pour

    1

    East FDN Cure

    2

    East FDN Strip

    1 South FDN Form

    6

    South FDN Rebar

    2

    South FDN Pour

    1

    South FDN Cure

    2

    South FDN Strip

    1 West FDN Form

    6

    West FDN Rebar

    2

    West FDN Pour

    1

    West FDN