PLANNING ENGINEERING AND PROJECT MANAGEMENT Lecture#06 PLANNING ENGINEERING AND PROJECT MANAGEMENT By Lec. Junaid Arshad DEPARTMENT OF ENGINEERING MANAGEMENT

Topics Covered Dependent and Independent Activities Dependency and Precedence Relationship Project Scheduling Guidelines for Estimating Duration Probability Considerations in Project Scheduling Gantt Chart

Dependent and Independent Activities An essential concept behind project planning is that some activities are dependent on other activities being completed first. As an example, you cannot start building a bridge before you have finished designing it. These dependent activities need to be completed in a sequence, with each activity being completed before the next activity can begin. We can call dependent activities sequential or linear.  Independent activities are not dependent on completion of any other activity. These are nondependent or parallel activities.

Dependency and Precedence Relationship Dependency is the timing relationship that exists between two activities. The earlier activity in a dependency relationship is referred to as the predecessor and the later is known as successor. The precedence relationship is given by defining the immediate preceding activities.

Precedence Relationship Immediately preceding Activity Description

Precedence Relationship Predecessors (Dependencies)   Activity Predecessors (Dependencies) A - B C D E F G H I J G - H

Project Scheduling Project scheduling involves sequencing and allotting time to all project activities. At this stage, managers decide how long each activity will take and compute how many people and materials will be needed at each stage.

Accurate Project Scheduling requires an understanding of : The interdependencies among project activities and events (network diagramming) The duration of various activities that comprise the network (duration estimating) The availability of resources (resource leveling) Mathematical models for analyzing these interdependencies and availabilities (Pert and CPM)

of starting and completion (dates) of the Project Schedule: Project Schedule shows the time frame of starting and completion (dates) of the activities constituting the project. PMI defines the Project Schedule as The planned dates for performing project activities and meeting project milestones.

Activity In the definition of schedule, activities refer to the lowest level elements of WBS. An activity consume resources and takes time to complete. Event The start point or the finish point of one or more activities. An event occurs at a particular point in time without duration. Event does not consume resources. Milestone Milestones refer to key events in a project. Milestones are important checkpoints for a project. Milestones can be used to catch scheduling problems early.

Guidelines for Estimating Duration Duration estimating involves assessing the number of work periods (hours, days, weeks) required to complete each individual activity. Guidelines for Estimating Duration The following guidelines are offered to assist in the duration estimating process and to improve estimating accuracy.

Note: These guidelines have been developed assuming that resources are being considered conceptually, but not actually assigned at this time. Obviously, the labour resources assigned to a task can affect its overall duration. It is common to estimate task duration first by thinking conceptually about the level of resource assignments. Once resources are actually assigned, the activity durations can be further refined and adjusted as necessary.

Whenever possible, make use of in-house experience Whenever possible, make use of in-house experience. Seek out individuals who may have performed activities in the past. Have the people who will be responsible for performing a given task provide duration estimates. This does not mean talking only to task managers, but also to technicians, field engineers etc. These individuals have a tremendous amount of knowledge that should not be overlooked. Make all time estimates realistic, without an optimistic or pessimistic view.

Assume that the work will be performed with a normal level of labour and equipment. Although completion of tasks can often be accelerated by adding more people and/or equipment it is best not to assume an exaggerated level of effort. An exception would be where an analysis of the network indicates that the customer’s required finish date can not be met with a normal level of effort. Assume a normal workweek and a normal workday. Use consistent time units for all activity durations.

7.Be willing to break activities into smaller units (work packages) if there seems to be great difficulty in estimating a particular activity. (If this is done the work breakdown structure and network diagram will require updating) 8.Do not assume that a worker will have eight hours of uninterrupted time to work on a task e.g. office workers are constantly interrupted by phone calls, other office personnel, meetings. 9.Because reports require revisions, be sure to include editing time (beyond your original estimate) for making the necessary changes.

Probability Considerations in Project Scheduling Two types of time estimates are used for activity duration. Deterministic times or definite times, where the activity duration can be calculated from the quantity of work, rate of work done with a specific resource allocation. Probabilistic time estimates are used when past data or knowledge is insufficient or where uncontrollable environmental factors exist.

TE=(a + b + 4m)/6 Expected Time: Probability considerations are incorporated in project scheduling by assuming that the time estimate for each activity is based on three different values a = optimistic time (which will be required if execution goes extremely well) b = pessimistic time (which will be required if execution goes badly) m = most likely time (which will be required if execution is normal) TE=(a + b + 4m)/6 Expected Time:

mid point=(a + b)/2 most likely time=m The most likely time is given double weightage than the mid point for calculating the arithmetic means Arithmetic means of (a + b)/2 and 2m = (a + b)/2 + m + m 3 = (a + b + 4m)/6 Expected Time

Note: Activity Optimistic time a Most likely time m Pessimistic time b Expected time (TE) x 4 10 16 y 2 12 11 z 6 38 18 Note: The most likely estimate ‘m’ need not to coincide with the midpoint (a + b)/2

Gantt Chart One popular project scheduling approach is the Gantt chart. Gantt charts are low cost means of helping managers to make sure that All activities are planned for Their order of performance is accounted for The activity time estimates are recorded The overall project time is developed

In a Gantt chart, each activity takes up one row In a Gantt chart, each activity takes up one row. Activities may run sequentially or in parallel. Dates run along the top in increments of days, weeks or months, depending on the total length of the project. Decide what resolution to use in the timeline. For projects of three months or less, use days, for longer projects use weeks or months, and for very short project use hours. The expected time for each activity is represented by a horizontal bar whose left end marks the expected beginning of the activity and whose right end marks the expected completion date.

Gantt Chart Task Duration Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1 2 mo.   2 3 4 5 6

Monitoring When a project is under way, Gantt Charts are useful for monitoring its progress. You can immediately see what should have been achieved at a point in time, and can therefore take remedial action to bring the project back on course. As the project progresses, the chart is updated by filling in the bars to a length proportional to the fraction of work that has been accomplished on the activity.

This way, one can get a quick reading of project progress by drawing a vertical line through the chart at the current date. Completed activities lie to the left of the line and are completely filled in. Current activities cross the line and are behind schedule if their filled-in section is to the left of the line and ahead of schedule if the filled-in section stops to the right of the line. Future activities lie completely to the right of the line.

In constructing a Gantt Chart, keep the activities to a manageable number (no more than 15 or 20) so that the chart fits on a single page. More complex projects may require subordinate charts which detail the timing of all the subtasks which make up one of the main tasks. For team projects, it often helps to have an additional column containing numbers or initials which identify who on the team is responsible for the task.

Gantt Chart

Gantt Chart

Gantt Chart

Q&A