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9-1 ELC 347 project management Day 19. Agenda Integrative Project –IP part 4 not graded yet –Part 5 Due Nov 22 (page 318) –Any of the first five sections.

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Presentation on theme: "9-1 ELC 347 project management Day 19. Agenda Integrative Project –IP part 4 not graded yet –Part 5 Due Nov 22 (page 318) –Any of the first five sections."— Presentation transcript:

1 9-1 ELC 347 project management Day 19

2 Agenda Integrative Project –IP part 4 not graded yet –Part 5 Due Nov 22 (page 318) –Any of the first five sections can be resubmitted for rescoring prior to finals week. The recorded score will the average of the original score and the score on the resubmitted section. Assignment 7 posted, Due Nov 18 Exam 2 Nov 22 –Chap 6-10 Today will discuss Project Scheduling: Lagging, crashing and Activity networks 6-2

3 Schedule for rest of semester Today –Chap 10 Nov 18 –Group work –Assignment 7 due Nov 22 –Quiz 2 Chaps 5-10 –IP part 5 Due Nov 29 –Chap 11 Dec 2 –Chap 12 Dec 6 –Group Work –Assignment 8 due Dec 9 –Chap 13 & 14 –IP Part 6 due Dec 13 @ 1 PM –Quiz 3 Chaps 11 - 15 –IP Projects due 6-3© 2007 Prentice-Hall, Inc

4 Project Scheduling: Lagging, Crashing and Activity Networks Chapter 10 © 2007 Pearson Education

5 Lags in Precedence Relationships The logical relationship between the start and finish of one activity and the start and finish of another activity. Four logical relationships between tasks 1.Finish to Start 2.Finish to Finish 3.Start to Start 4.Start to Finish

6 Finish to Start Lag Most common type of sequencing Shown on the line joining the modes –Added during forward pass –Subtracted during backward pass 0 A 6 Spec Design 6 6 B 11 Design Check 5 15 C 22 Blueprinting 7 Lag 4 This lag is not the same as activity slack

7 Finish to Finish Lag Two activities share a similar completion point –The mechanical inspection cannot happen until wiring, plumbing, and HVAC installation are complete 10 A 16 Plumbing 6 16 B 21 HVAC 5 21 C 22 Inspection 1 15 D 21 Wiring 6

8 Start to Start Lag 31 A 33 Plumbing 6 33 B 36 HVAC 5 36 C 37 Inspection 1 30 D 36 Wiring 6 Lag 3 Logic must be maintained by both forward and backward pass

9 Start to Finish Lag Least common type of lag relationship Least common type of lag relationship Successors finish dependent on predecessors start Successors finish dependent on predecessors start 22 A 28 Plumbing 6 28 B 33 HVAC 5 33 C 34 Inspection 1 30 D 36 Wiring 6 Lag 3 fssf.mpp

10 Gantt Charts Establish a time-phased network Can be used as a tracking tool Benefits of Gantt charts 1.Easy to create and comprehend 2.Identify the schedule baseline network 3.Allow for updating and control 4.Identify resource needs

11 Create a Gantt chart based on the activities listed in the table. TaskTimePredTaskTimePred Z8--U3W Y5ZT6V X8ZS7U,T W4Y,XR9S V5W gantt.mpp

12 Gantt Chart With Resources in MS Project

13 Crashing Projects Accelerating a project by committing more resources than initially planned Principal methods for crashing Improving existing resources productivity Changing work methods Increasing the quantity of resources

14 CRASHING PROJECTS – UNDER WHAT CONDITIONS? The initial schedule may be too optimistic. Market needs change and the project is in demand earlier than anticipated. The project has slipped considerably behind schedule. The contractual situation provides even more incentive to avoid schedule slippage. 9-14

15 CRASHING ACTIVITIES – AN EXAMPLE Formula Slope = crash cost – normal cost normal time – crash time Example – Calculating the Cost of Crashing SUPPOSE: NORMAL ACTIVITY DURATION = 8 WEEKS NORMAL COST = $14,000 CRASHED ACTIVITY DURATION = 5 WEEKS CRASHED COST = $23,000 THE ACTIVITY COST SLOPE = 23,000 – 14,000 or, $9,000 = $3,000 per week 8 – 5 3


17 Managerial Considerations Determine activity fixed and variable costs The crash point is the fully expedited activity Optimize time-cost tradeoffs Shorten activities on the critical path Cease crashing when –the target completion time is reached –the crash cost exceeds the penalty cost

18 Project costs PreNormalCrashedCrash/dayDays Gained activityDurationCostDurationCost A51000315002502 BA7700610003001 CA325002400015001 DA5 5 -0 EC,D937506900017503 FB41600325009001 GD62400430003002 HE,F,G990051500020004 Total2245037500



21 Other costs Previous examples only includes direct costs What about –Indirect costs (overhead) $ per day overhead –Late penalties $ per day late


23 What is the lowest cost to complete this project in 53 weeks? Times are in weeks and costs in dollars. ActivityPredNormal Time Min Time Normal Cost Crash Cost A--1495001500 BA5210001600 CA10820002900 DB, C8510002500 ED6516001900 FD9615003000 GE, F746001800 HG151116003600 crash.mppcrash.mpp, crash.xlscrash.xls

24 Activity on Arrow Networks Activities represented by arrows Widely used in construction Event nodes easy to flag Forward and backward pass logic similar to AON Two activities may not begin and end at common nodes Dummy activities may be required


26 Project delta ActivityPreDuration A5 BA5 CA6 DB,C13 EB6 FD4 GC9 HE,F,G2

27 Two Succesors

28 AOA Network

29 Forward Pass

30 Backwards pass

31 1.Use AOA to sketch the network that represents the project as described in the table. 2.Calculate early and late start and finish times for all activities. ActivityTimePredActivityTimePred A3--F4D B5AG2C C7AH5E,F,G D3B,C E5B

32 9-32

33 Controversies in the Use of Networks Networks can be too complex Poor network construction creates problems Networks may be used inappropriately When employing subcontractors –The master network must be available to them –All sub-networks must use common methods Positive bias exists in PERT networks

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