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MANAJEMEN PROYEK PERANGKAT LUNAK Program Pendidikan Vokasi Universitas Brawijaya Tahun 2011

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Pertemuan 5 Perencanaan Proyek : PDM (Presedence Diagramming Method) PDM (Presedence Diagramming Method) CPM (Critical Path Method) CPM (Critical Path Method)

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Critical Path Method Advantages: Identifies activities that control the project length Determines shortest time for completion Identifies activities that are critical (i.e. cannot be delayed) Shows available float for non-critical activities Allows evaluation of what-if scenarios Allows monitoring & control of fast-track projects With software can be resource loaded and leveled

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Critical Path Method Disadvantages Only as good as the effort put forth to properly model the plan Can be difficult to properly update Can be easily misused May lead to a false sense of security Actual conditions may necessitate significant modifications to model to accurately reflect reality

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Precedence Diagramming Method (PDM) PDM network rules: Activities are represented by boxes or nodes that are assigned properties of the activity they represent Precedences are shown by arrows that have both direction and time properties Precedences consist of two parts: A relationship and a lag value or constraint Finish – to – StartFS Finish – to – FinishFF Start – to – StartSS Start – to – FinishSF Lag = x Days ( a negative lag is called a lead)

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PDM – Precedence Diagram PDM activities are comprised of: Activity descriptions Nodes representing the activity Arrows representing relationship / dependency Points indicating direction of relationship / dependency

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PDM Logic Relationships Finish to Start (FS) – Activity A must Finish before Activity B may Start. The lag is usually zero. FS is the most common type. Start to Finish (SF) – Activity A must start before Activity B may Finish. The lag is usually greater than either activity duration. FS is the least common type. Activity AActivity BActivity AActivity B

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PDM Logic Relationships Finish to Finish (FF) – Activity A must Finish before Activity B may Finish. The lag value is usually greater than zero. FF is a less common type. Start to Start (SS) – Activity A must Start before Activity B may Start. The lag value is usually greater than zero. SS is a less common type. Activity AActivity BActivity AActivity B

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PDM Time Calculations Once the Network is constructed and duration of each activity is estimated, we can determined the following four time values: Earliest Start (ES) – The earliest possible time an activity can begin Earliest Finish (EF) – The earliest possible time an activity can finish Latest Start (LS) – The latest possible time an activity can start without delaying project completion Latest Finish (LF) – The latest possible time an activity can start without delaying project completion

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PDM Time Calculations ES and EF are determined by making a Forward Pass (left-to-right) through the Network. ES of an activity is equal to the latest of early finish times of its predecessors. EF is the total of the activity ES plus its duration. LS and LF are determined by making a Backward Pass (right-to-left) through the Network. LF of an activity is equal to the smallest of the LS times of the activities exiting from the activity in question. LS of an activity is equal to its LF minus its duration.

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PDM Activity Notation and Assumptions Each activity box consists of six cells For the following example assume all activities: Begin on the morning of the scheduled start date End the evening of the scheduled finish date Using a 7-day workdays per week calendar 4E6 11213 ES EF Activity Duration LSLF 0 Lag

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Forward Pass Example 6D9 4 8E8 1 4F10 7 12G18 7 2 0 0 (F to G) 10 + 0 + 1 = 11 (E to G) 8 + 0 + 1 = 9 (D to G) 9 + 2 + 1 = 12 Largest ES Early Start Calculations Early Finish Calculation 12 + 7 – 1 = 18

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Backward Pass Example 18H24 25731 18I21 24427 18J 341 14K17 19422 2 0 0 (H to K) 25 - 2 - 1 = 22 (I to K) 24 - 0 - 1 = 23 (J to K) 34 - 0 - 1 = 33 Late Finish Calculations Late Start Calculation 22 - 4 + 1 = 19

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CPM Example Exercise A 6d B 11d C 20d H J D 13d E 9d F 20d G 6d I 13d FSFFSSSF

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CPM Example Exercise Forward Pass Results A 6d B 11d C 20d H J D 13d E 9d F 20d G 6d I 13d 1d6d7d17d18d37d63d82d 1d20d21d33d34d42d43d62d 34d39d40d52d

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CPM Example Exercise Backward Pass Results A 6d B 11d C 20d H J D 13d E 9d F 20d G 6d I 13d 1d6d7d17d18d37d63d82d 1d20d21d33d34d42d43d62d 34d39d40d52d 4d9d10d20d43d62d63d82d 1d20d21d33d34d42d43d62d 44d49d50d62d

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CPM Example Exercise Backward Pass Results A 6d B 11d C 20d H J D 13d E 9d F 20d G 6d I 13d 1d6d7d17d18d37d63d82d 1d20d21d33d34d42d43d62d 34d39d40d52d 4d9d10d20d43d62d63d82d 1d20d21d33d34d42d43d62d 44d49d50d62d

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CPM – Float (or Slack) and Critical Path Additional Network calculations provides other important information allowing analysis and control: Total Float (TF) – The amount of time an activity can be delayed without delaying the overall project completion, which is equal to Late Finish minus Early Finish. Free Float (FF) – The amount of time an activity can be delayed without delaying the start of another activity. Can be determine by subtracting the smallest Total Float going into an activity from each predecessor into that activity. Critical Path – The path through the Network that has the longest total duration, thus it defines the shortest period of time in which the project may be completed.

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Float Calculation Example

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CPM Example Exercise Continue with Exercise A 6d B 11d C 20d H J D 13d E 9d F 20d G 6d I 13d 1d6d7d17d18d37d63d82d 1d20d21d33d34d42d43d62d 34d39d40d52d 4d9d10d20d43d62d63d82d 1d20d21d33d34d42d43d62d 44d49d50d62d

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CPM Example Exercise Float Results A 6d B 11d C 20d H J D 13d E 9d F 20d G 6d I 13d 1d6d7d17d18d37d63d82d 1d20d21d33d34d42d43d62d 34d39d40d52d 4d9d10d20d43d62d63d82d 1d20d21d33d34d42d43d62d 44d49d50d62d 3d 25d0d 10d

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CPM Example Exercise Critical Path Traced A 1d6d 4d3d9d B 7d11d17d 10d3d20d C 18d20d37d 43d25d62d H 63d20d82d 63d0d82d J 1d20d 1d0d20d D 21d13d33d 21d0d33d E 34d9d42d 34d0d42d F 43d20d62d 43d0d62d G 34d6d39d 44d10d49d I 40d13d52d 50d10d62d FSFFSSSF

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SEKIAN 23

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