Presentation on theme: "Project Scheduling Critical Path Method"— Presentation transcript:
1 Project Scheduling Critical Path Method Based on material from Chapter 6 of Project Management and Teamwork, by Karl Smith
2 How do you schedule complex projects? Make a list of things to do?Use an outline?Draw a concept map?Focus on those things we know how to do first?Use project management software?
3 Dinner & Concert How much time do you need to prepare and consume the meal? Menu consists of soup and baked chickenSoup must be boiled 35 minutes and will allow 15 minutes to serve and consumeChicken dish requires 30 minutes to boil rice, 15 minutes to brown chicken in frying pan, 15 minutes to bake rice and chicken in baking dishSauce takes 5 minutes to prepare in frying pan and 15 minutes to boil peasOnly have two pots and one frying panWine takes 5 minutes to uncork and 30 minutes to let breath before servingAllow 25 minutes to serve and consume entrée and wine
5 Critical Path MethodWork breakdown structure ok for simple task with few activitiesWhen number of task large, a systematic solution is to use the Critical Path Method (CPM)to use CPM must know the duration of each activity and the predecessors of each
6 CPM - Forward PassEarly Start (ES) - Earliest time that each activity can start- obtained by adding the earliest start of its latest starting predecessor to the that predecessor’s duration- when two or more activities must be competed before the next one can start, then the maximum must be usedEarly Finish (EF) - Determined by summing the early start (ES) and duration
8 CPM - Backward PassLate Start (LS) - Latest possible starting time that each activity can have- calculated as the earliest starting successor, less the duration of the activity under considerationLate Finish (LF) - The resulting finish time based on late start (LS)
10 CPM - Critical Path & Floats Critical Path - The path for which activities cannot be delayed- activities on critical path will have equal earliest and latest times and are call criticalFloats - The amount the termination of an activity can be delayed before delaying a successor is called free float (FF). FFi = (ESi+1) min - ESi - DiThe amount of slack an activity has before it would cause the path on which it lies to become critical is called the total float (TF). TFi = LFi - EFi
12 CritPath Program http://www.ce.umn.edu/~smith Allows easy entry of activitesProvides critical path calculations (ES, EF, LS, LF, Float) and algorithm stepperCalculates critical pathGives associated Gantt Chart - a time-scaled network (Gantt Chart does not show interdependence)
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