PLANNING ENGINEERING AND PROJECT MANAGEMENT Lecture#07 PLANNING ENGINEERING AND PROJECT MANAGEMENT By Lec. Junaid Arshad DEPARTMENT OF ENGINEERING MANAGEMENT

Topics Covered Network Representation Network Development Dummy Activity Network Scheduling Practice Problems CPM Network Calculations

Network Representation Even though a linked Gantt Chart can include precedence relationships between activities, it is an unsuitable tool if these relationships grow beyond a certain complexity. In such situations, the scheduling should be carried out by a network technique. However, the presentation of the schedule to the project participants may still be done in a Gantt Chart format.

Arrows and nodes are used for construction of Network Arrows and nodes are used for construction of Network. There are two types of network representations: 1. Activity on arrow (AOA) 2. Activity on node (AON) Arrow Node Node

1. Activity on arrow (AOA) Event In AOA Arrow shows activity and precedence relationships 2. Activity on node (AON) Node Activity In AON Arrow shows precedence relationships only

For structure of network Network Development Following information is required in order to develop a network: A list of all activities A list of all precedence relationships An estimated duration of each activity (required for network scheduling) For structure of network

Problem 1 Activity Immediate Predecessor (s) A - B C D Table for network development

Problem 1 Act-ivity Immediate Predecessor A - B C D C D A B Activity on arrow (AOA) Act-ivity Immediate Predecessor A - B C D C D A B

Problem 1 Activity on arrow (AOA) 2 C A 4 1 B D 3

Problem 1 Activity on node (AON) D C A B START END

Dummy Activity An activity inserted into the network to maintain the logic of the network. A dummy takes zero time and do not consume any resources.

Dummy Activity A precedes B and C, B and C precede D B A 1 2 3 D 4 C Incorrect Display

Dummy Activity A precedes B and C, B and C precede D Correct Display 2 Add a Dummy as shown by dash line below. 2 4 1 A C B D 3 5

Problem 2 Activity Preceding Activity A - B C D E C,D F G H Table for network representation

General Hospital’s Activities and Predecessors Activity Description Immediate Predecessors A Build internal components - B Modify roof and floor C Construct collection stack D Pour concrete and install frame A, B E Build high-temperature burner F Install pollution control system G Install air pollution device D, E H Inspect and test F, G Table for network representation

AON Network for General Hospital Start A B C D E F G H Arrows show precedence relationships

AOA Network for General Hospital C Construct stack 1 3 2 4 5 6 7 A Build internal components Install controls F Dummy Activity Build burner E H Inspect/Test Modify roof/floor B Install pollution control device G D Pour concrete/ Install frame

A Comparison of AON and AOA Network Conventions

Problem 3 Activity Preceding Activity A - B C D E F G H D, E I F, G Table for network representation

Network Scheduling The purpose of network scheduling is To determine when the project will finish To determine which activities directly influence the project duration Two techniques of network scheduling are: Critical path method (CPM) Program evaluation and review technique (PERT)

PERT and CPM Developed in 1950’s CPM by DuPont Cooperation for chemical plants (1957) PERT by Booz Allen Hamilton with the U.S. Navy, for Polaris missile (1958) Consider precedence relationships and interdependencies Each uses a different estimate of activity times What circumstances lead the two organizations to develop different, yet similar tools for the management of complex projects? In your discussion of PERT/CPM, you should probably note that PERT helps us identify critical tasks/activities and look at the probability of completing the project by a given date; CPM helps us analyze the cost/time tradeoffs possible if we need to speed the project up.

Questions which may be addressed by PERT & CPM Is the project on schedule, ahead of schedule, or behind schedule? Is the project over or under cost budget? Are there enough resources available to finish the project on time? If the project must be finished in less than the scheduled amount of time, what is the way to accomplish this at least cost?

Six Common Steps to PERT & CPM Define the project and prepare the work breakdown structure. Develop relationships among the activities. (Decide which activities must precede and which must follow others.) Draw the network connecting all of the activities Assign time (and/or cost) estimates to each activity Compute the longest time path through the network. This is called the critical path Use the network to help plan, schedule, monitor, and control the project

CPM Network Calculations CPM calculates a network in several steps: For each event: Earliest possible time: The earliest possible time the event can occur Latest possible time: The latest possible time the event can occur

For each activity: Early start (ES): The earliest possible start time for the activity Early finish (EF): The earliest possible finish time for the activity

For each activity: Late start (LS): The latest possible start time for the activity so as not to delay the completion time of the entire project. Late finish (LF): The latest possible finish time for the activity so as not to delay the completion time of the entire project. Continue to next lecture

Q&A