GPE engineering project management Project Management in an Engineering Context
Network diagrams in context PM SOW CHARTER SCOPE DEFINITION WBS circulation, negotiation, translation WBS WP à activities ----- estimation Time AOA GANTT Cost PERT AON ----------- planning, resource allocation, cost allocation, control ---------Mainly PMBOK chapter 6
Network diagrams WBS
PERT Program Evaluation & Review Technique
WBS GANTT PERT
Network Analysis (PERT Program Evaluation & Review Technique; CPM Critical Path Method) Network modulation approach used in planning, scheduling and controlling projects. Beyond the analysis they facilitate, they represent a common ground to discuss options so they are excellent communication tools. They facilitate thematic brain-storming analysis Network diagrams are entity/relationship models (interrelations among instances of resources) usually used in project planning, namely on scheduling and time management Using these models we need to take into account: interrelation of activities (sequencing relations) and relations among activities and resources (allocation) There are more complex models, using statistics but we will eventually address them later
Critical Path Method (CPM) (deterministic) A schedule network analysis technique used to determine the amount of scheduling flexibility (the amount of float) on various logical network paths in the project schedule network, and to determine the minimum total project duration. Early dates are calculated by means of a forward pass, using a specified start date. Late dates are calculated by means of a backward pass, starting from a specified completion date, which sometimes is the project early finish date calculated during the forward pass calculation. Program Evaluation and Review Technique (PERT) (probabilistic) A technique used to improve the accuracy of the cost or duration estimates of project components when there is uncertainty. PERT uses weighted averages of optimistic, pessimistic, and most likely estimates (the well-known three-point estimates) of the components' cost or duration. Different weighting schemes represent different probability distributions of the possible cost or duration of a component. For instance, the typical formula is [(optimistic + 4 times the most likely + pessimistic) divided by 6], approximates a beta distribution.
CPM/PERT Critical Path Method (CPM) DuPont & Remington-Rand (1956) Deterministic task times Activity-on-node network construction Project Evaluation and Review Technique (PERT) US Navy, Booz, Allen & Hamilton Multiple task time estimates (probabilistic) Activity-on-arrow network construction
PERT elements Events (states), activities (nature and time), preceding, allocation, context (context must always be defined and clarified) Some examples of PERT representation - AOA activity on arrow, or ADM - arrow diagramming method; and AON activity on node A,3 B,5 C,7 D,2 E,6 F,3 G,10
PERT elements Events (states), activities (nature and time), preceding, allocation, context (context must always be defined and clarified) Some examples of PERT representation - AOA activity on arrow, or ADM - arrow diagramming method; and AON activity on node A,3 B,5 C,7 D,2 E,6 F,3 G,10 17 19
Examplesof different notations
Parallel activities signaled as we exemplify are not allowed A B A,B A B dummy If you fail this notation in the exam you will have 0 in the entire question
Task B can only be started after activity A is completed. The same with D and C A,3 B,7 C,4 D,6 10 10
Network Analysis example AOA A,3 B,7 C,4 D,6 There is a dummy activity duration 0 (only a logical dependency)
Network Analysis example AOA A,3 B,7 C,4 D,6 10 10 Are all paths identified?
Network Analysis example AOA A,3 B,7 C,4 D,6 10 10 11 No, there are three paths, not two! And that makes quite a difference!!
Network Analysis example AOA A,3 B,7 C,4 D,6 10 10 11 (A,B) (C,B) (C,D) Instant time - 5 Time interval - 6
Network Analysis example AOA A,3 B,7 C,4 D,6 10 10 11 Activity Duration Early St Early Fi Latest St Lat. Fi. Float A B C D Dummy
Network Analysis example AOA A,3 B,7 C,4 D,6 10 10 11 Activity Duration Early St Early Fi Latest St Lat. Fi. Float A 3 0 3 1 4 1 B 7 4 11 4 11 0 C 4 0 4 0 4 0 D 6 4 10 5 11 1 Dummy 0 4 4 4 4 0 Instant times
PERTS, and projects 1. Define the project and all its activities. The project is made of tasks and all tasks should have a single start and a single finish 2. Develop the relationships among the activities. Decide which activities must precede, which must follow others, and the ones that can be executed in parallel. If you are short in time try to put in parallel as much activities as you can 3. Draw the network diagram connecting all the activities. Each activity is unique. Dummy activities are immaterial in time but relevant in sequence, they impose logical dependences 4. You can assign time and cost to each activity Preceded by a planning effort by the project management team. This planning effort is part of the Develop Project Management Plan process 5. Compute the longest time path through the network. This path is called the Critical Path 6. Use the network to help plan, schedule, monitor and control the project and also as a communication tool documented in the schedule management plan
PERTS, and projects
PERTS, and projects
WBS GANTT PERT
Late start and backward path backward pass Early dates are calculated forwards, using the forward path. Late dates are calculated in reverse direction, starting at the date of the finishing of the project this is the backward path In this example one backward path leads us to event 3 through activity B. So we have: Total project time (critical path) = 11 11-7 = 4. This means that the late start for activity B is 4 Relating to event 2 we have to evaluate two paths, Dummy and D. Through Dummy we have 4-0 = 4, this means that Dummy late start is 4 and through D we have 11-6 = 5, so activity D late start is 5 Activ ity Dura tion Early St Early Fi Lates t St Lat. Fi. Float A,3 3 B,7 A 3 0 3 1 4 1 B 7 4 11 4 11 0 C 4 0 4 0 4 0 D 6 4 10 5 11 1 Dum my 0 4 4 4 4 0 DUMMY,0 C,4 D,6 2 4
So you already have the rule to compute early starts and late starts. Early starts are computed in the forward path from the beginning to the end, adding duration and late starts are computed in the backwards path, subtracting duration from the end Project management tools compute this for you, you just have to manage according to situated conditions (environment, resources, risk, )
Your project is to design and develop an electric motor. Activity durations and predecessors are identified at the following table. A) construct a PERT AOA; B) Which is the duration of every path? Which path is the critical one? C) What happens if activity E duration becomes 8? Activity duration predecessor A 10 - B 20 - C 4 - D 2 A E 10 B,C F 8 B,C G 4 B,C H 2 C I 6 G,H J 2 D,E
Network Analysis example AOA Activity duration predecessor A 10 - B 20 - C 4 - D 2 A E 10 B,C F 8 B,C G 4 B,C H 2 C I 6 G,H J 2 D,E
Network Analysis example AOA Activity duration predecessor A 10 - B 20 - C 4 - D 2 A E 10 B,C F 8 B,C G 4 B,C H 2 C I 6 G,H J 2 D,E 8 paths CP
Network Analysis example AOA Activity duration predecessor A 10 - B 20 - C 4 - D 2 A E 10 B,C F 8 B,C G 4 B,C H 2 C I 6 G,H J 2 D,E 8 paths E from 10 to 8: 30 CP CP 14
Network Analysis example AOA à AON A,3 AOA AON C,4 A,3 B,7 D,6 B,7 END BEGIN C,4 D,6 With AON you don t have dummies
Network Analysis example AON A,10 Activity duration predecessor A 10 - B 20 - C 4 - D 2 A E 10 B,C F 8 B,C G 4 B,C H 2 C I 6 G,H J 2 D,E D,2 J,2 B B,20 C,4 E,10 END F,8 G,4 H,2 I,6 ADJ 14 BEJ 32 BF 28 BGI 30 CEJ 16 CF 12 CGI 14 CHI 12