2 Project Management Projects are typically characterized as: one-time, large scale operationsconsuming large amount of resourcesrequiring a long time to completea complex set of many activities3 Important Project Management Functions:Planning – determine what needs to be doneScheduling – decide when to do activitiesControlling – see that it’s done right
3 PERT/CPM project management technique (Program Evaluation & Review Technique)/(Critical Path Method)Inputslist of activitiesprecedence relationshipsactivity durationsOutputsproject durationcritical activitiesslack for each activity
4 Excavate & pour footings 12Excavate & pour footingsPour foundationInstall drainsProject Network for House Construction3674895101112161813171514Install roughelectrical & plumbingPourbasementfloorInstallcooling &heatingErectframe & roofLaybrickworkstormdrainsdrywallflooringfinishedplumbingkitchenequipmentPaintFinishroofdrainagegradingfloorswalks;Landscapeelectricalworkcarpeting
5 CPMA project has the following activities and precedence relationships:Immediate ImmediatePredecessor PredecessorActivity Activities Activity Activitiesa f c,eb a g bc a h b,dd a i b,de b j f,g,hConstruct a CPM network for the project using:1.) Activity on arrow2.) Activity on node
9 Critical Path path any route along the network from start to finish Critical Path path with the longest total durationThis is the shortest time the project can be completed.Critical Activity an activity on the critical path*If a critical activity is delayed, the entire project will be delayed. Close attention must be given to critical activities to prevent project delay. There may be more than one critical path.To find critical path: (brute force approach)identify all possible paths from start to finishsum up durations for each pathlargest total indicates critical path
11 Slack TimesEarliest Start (ES) – the earliest time an activity can startES = largest EF of all immediate predecessorsEarliest Finish (EF) – the earliest time an activity can finishEF = ES + activity durationLatest Finish (LF) – the latest time an activity can finishwithout delaying the projectLF = smallest LS of all immediate followersLatest Start (LS) – the latest time an activity can startLS = LF – activity duration
12 Slack Times Slack how much an activity can be delayed without delaying the entire projectSlack = LF – EF or Slack = LS – ESSlackEFLFESLS
13 c = 10g = 12f = 17b =15a = 10e = 15i = 7d = 20h = 9
15 Input Table for Microsoft Project (Example 10.1, page 387)
16 Gantt Chart for Microsoft Project (Example 10.1, page 387)
17 Project Network for Microsoft Project (Example 10.1, page 387)
18 Activity Crashing (Time-Cost Tradeoffs) An activity can be performed in less time than normal, but it costs more.Problem: If project needs to be completed earlier than normal, which activity durations should be decreased so as to minimize additional costs?Guidelines:Only crash critical activitiesCrash activities one day at a timeCrash critical activity with lowest crashing cost per day firstMultiple critical paths must all be crashed by one day
19 Activity Crashing Example Crash project as much as possible.a = 3b = 4c = 8d = 5ActivityDurationCrashedCostCrashingCost/daya324045b45054c8568d3033Minimum duration = 9 days; Total additional cost = $30
20 Program Evaluation & Review Technique (PERT) 3 duration time estimatesoptimistic (to), most likely (tm), pessimistic (tp)Activity duration:mean te = (to + 4tm + tp) / 6variance Vt = [(tp – to) / 6]2Path duration:mean of path duration = T = Σ tevariance of path duration = σ2 = Σ Vt
21 X = T ± ZσpathZ is number of standard deviations that X is from the mean.Example: If the mean duration of the critical path is 55 days and the variance of this path is 16, what is the longest the project should take using a 95% confidence level?
23 probabilityof being late.05ZσcpactualprojectdurationT55X
24 PERT ExampleIf the expected duration of a project is 40 days and the variance of the critical path is 9 days, what is the probability that the project will complete in less than 45 days?in more than 35 days?in less than 35 days?in between 35 and 45 days?
25 probabilityof being lateZσcpactualprojectdurationT4045
26 PERT ExampleThe expected duration of a project is 200 days, and the standard deviation of the critical path is 10 days. Predict a completion time that you are 90% sure you can meet.
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