OPMA 5364 Project Management Part 5 Project Scheduling Topic Outline Project Scheduling Identifying relationships among activities Project network diagrams Identifying critical paths and critical activities Determining activity slack times Gantt charts Project scheduling exercise Microsoft Project example Other precedence relationships Management of project schedules Part 5 Project Scheduling 2 Identifying Activity Relationships In addition to estimating activity time duration and cost relationships among activities must also be identified Relationships What task immediately precedes this task What task immediately follows this task What tasks can be done concurrently These are referred to as precedence relationships The main relationship for scheduling is what task immediately precedes the current task which is referred to as the immediate predecessor task Part 5 Project Scheduling 3 Project Network Diagrams Network diagrams show the precedence relationships among activities It s easier to understand these relationships graphically Network diagrams help to understand the flow of work in a project Network diagrams are a useful tool for project planning and control as well as for scheduling One perhaps exaggerated claim is that the network represents of the planning process Part 5 Project Scheduling 4 2 Versions of Network Diagrams Activity on Arrow AOA networks also called Arrow Diagramming Method ADM simpler for projects with many dependencies emphasizes events milestones can be easily flagged sometimes requires dummy activities Activity on Node AON networks also called Precedence Diagramming Method PDM easier to draw for simple projects emphasizes activities no dummy activities Part 5 Project Scheduling 5 Activities vs Events Activity a chunk of work that is part of the project an activity may be broken down into multiple subactivities Event a significant point in time during the project such as a milestone event an event could be the time at which an activity is completed or the time at which related concurrent activities have all completed Dummy Activity an artificial activity with zero time duration that only shows a precedence relationship among activities Part 5 Project Scheduling 6 Activity on Arrow AOA Networks c e b g d f k k k or j j j Dashed lines are called dummy activities Activity m n r s Predecessor m n n m r n s Part 5 Project Scheduling 7 Install rough electrical plumbing 6 Pour basement floor Install drains 10 9 Erect frame roof 1 Excavate pour footings 2 Pour foundation 3 Install finished plumbing Install drywall Install cooling heating 7 11 8 Lay flooring 12 Install kitchen equipment Paint 4 Lay brickwork Finish carpeting 5 16 Finish electrical work Finish roof Project Network for House Construction Lay storm drains 13 14 Finish floors Install roof drainage AOA network 15 Part 5 Project Scheduling Finish grading 18 Pour walks Landscape 17 8 Project Network Example Task Pred Dur Task Pred a 4 g b 3 h c a 3 i d a 2 j e b 6 k f b 4 Draw AOA and AON networks Dur c d e f e g h i Part 5 Project Scheduling 1 4 5 6 1 9 Activity on Arrow AOA or ADM Network Initial Network Part 5 Project Scheduling 10 Activity on Arrow AOA or ADM Network Final Network c a d b e h f i g j k Part 5 Project Scheduling 11 Activity on Node AON or PDM Network Part 5 Project Scheduling 12 Project Network Example A project has the following activities and precedence relationships Predecessor Predecessor Activity Activities Activity Activities a f c e b a g b c a h b d d a i b d e b j f g h Draw AOA and AON networks Part 5 Project Scheduling 13 Activity on Arrow Initial Network Part 5 Project Scheduling 14 Activity on Arrow Final Network b a e c d g j f h i Part 5 Project Scheduling 15 Activity on Node Part 5 Project Scheduling 16 Critical Path path any route along the network from start to finish Critical Path path with the longest total duration This is the shortest time in which 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 Part 5 Project Scheduling 17 Critical Path Brute force approach to finding critical path 1 identify all possible paths from start to finish 2 sum up durations for each path 3 largest total indicates critical path This approach is inefficient but is instructive Part 5 Project Scheduling 18 d 4 2 6 k e c 4 i 4 f 5 3 6 3 b 2 1 a 6 g 9 7 8 j h 9 Part 5 Project Scheduling 7 5 19 Slack Times EST Earliest Start Time Largest EFT of all predecessors EFT Earliest Finish Time EST duration for this task LFT Latest Finish Time Smallest LST of following tasks LST Latest Start Time LFT duration for this task Slack LFT EFT or LST EST Part 5 Project Scheduling 20 Computing Slack Times EST EFT Task duration slack xxxx LST LFT Part 5 Project Scheduling 21 Slack Times Example Task Pred Dur Task Pred Dur a 4 g c d 1 b 3 h e 4 c a 3 i f 5 d a 2 j e g 6 e b 6 k h i 1 f b 4 For each task compute ES EF LF LS Slack Part 5 Project Scheduling 22 c 3 slack EST Task dur slack xxx LST g 1 slack a 4 slack EFT LFT j 6 slack d 2 slack Finish Start e 6 slack h 4 slack b 3 slack k 1 slack f 4 slack i 5 slack Part 5 Project Scheduling 23 Gantt Charts The main purpose of a Gantt chart is to display the schedule of activities They are easy to understand They are flexible in that you can also show other information on the chart such as resources required who is responsible critical activities percent complete etc All project management software packages will create Gantt charts Part 5 Project Scheduling 24 Gantt Chart Activity a b c d e f g h i Time weeks Part 5 Project Scheduling 25 Project Scheduling Exercise DynaTech Equipment Corp case Divide into small groups Read case 5 minutes Assignment 40 minutes List the immediate predecessors and WBS number for each activity Draw project network diagram lowest level Draw Gantt chart Determine project completion time Part 5 Project Scheduling 26 Microsoft Project Example Part 5 Project Scheduling 27 Microsoft Project Example Part 5 Project Scheduling 28 Microsoft Project Example Part 5 Project Scheduling 29 Other Precedence Relationships The typical precedence relationship between two activities is that when the first activity has finished then the second activity can start In this case the first activity is called the immediate predecessor of the