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Networks Part 2

Networks Part 2. More than you wanted to know!. Slack. Difference in the latest allowable date and the earliest possible date Activities with slack are where we can manage!. Standard Labeling. EF = Early Finish Earliest possible Finish date of event LF= Late Finish

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Networks Part 2

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  1. Networks Part 2 More than you wanted to know!

  2. Slack • Difference in the latest allowable date and the earliest possible date • Activities with slack are where we can manage!

  3. Standard Labeling • EF = Early Finish • Earliest possible Finish date of event • LF= Late Finish • Latest possible Finish date for an event without extending the due date for a project • S = LF - EF • Time we can wait (time we can manage!)

  4. Standard Labeling • ES = Early Start • Earliest possible Start date of event • LS= Late Start • Latest possible Start date for an event without extending the due date for a project • S = LS - ES • Time we can wait (time we can manage!)

  5. Depiction on Chart Name or Identification Early Start Early Finish A(8,10) 2(15,17) Duration Late Start Late Finish

  6. Example Activity Predecessor Duration A -- 3 B -- 2 C A 3 D A 7 E B 5 F C 6 G D,E 5

  7. Draw the Network Activity on Arrow A S B

  8. Draw the Network Activity on Arrow C A D S B E

  9. Draw the Network Activity on Arrow C A F D F S B G E

  10. Steps Front Pass • All numbers at start are 0 • Front Pass • Early Start (ES) is the Highest of the Early Finishes for all predecessors • Early Finish (EF) for an activity • ES for an activity + its own duration • EF/LF for finish is always the same

  11. Steps Back Pass • All numbers at Finish are equal to the highest early finish of predecessors • We will find late start and late finish • Late Finish (LF) for an activity • Lowest of late starts of all successors • Late start (LS) is LF – its own duration

  12. Slack • Slack = LF – EF • Slack = LS – ES • These should be the same • Critical Path is where slack is 0

  13. Depiction on Chart Name or Identification Early Start Early Finish A(8,10) 2(15,17) Duration Late Start Late Finish

  14. Draw the Network You make the call! C(3,6) 3(6,9) A(0,3) 3(0,3) F(6,12) 6(9,15) D(3,10) 7(3,10) F S G(10,15) 5(10,15) B(0,2) 2(3,5) E(2,7) 5(5,10)

  15. Now We Will Add Cost • Duration of activities can be affected by resources expended • The expected range of cost varies • There is a relationship that can be defined by a function • We will stick to linear relationships

  16. Crash • We define these relationships: • Range between costs at “normal time” and the fastest possible time (Crash) • Normal time/Crash time = TN/TC • Normal Cost/Crash Cost = CN/CC • Cost Slope CC - CN Cost slope = TC - TN

  17. Cost Slope Activity TN TC CN CC A 8 5 9 18 CC - CN Cost slope = TC – TN = 18 -9 5 – 8 = -3 Cost of Activity 18 9 5 8 Duration of activity

  18. Cost Slope • Slope of -3 means? • For every day (unit of time) that you speed up and activity it will cost you 3 $ • Each activity can be sped up • It costs money! • Where do we want to spend our money??

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