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11.
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Project Management A project is an interrelated set of activities with a
definite starting and ending point, which results in a unique outcome for a
specific allocation of resources (Krajewski et al., 2010). The complexity of
the project will increase with the size and number of activities within the
project. Extensive planning and co-ordination activities are required for
larger projects to ensure that the project aims are met. Examples of projects
include installing an IT system, building a bridge or introducing a new
service or product to the market. |
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11.1. |
Project Management Activities The project management process includes the following main
elements : |
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11.1.1 |
Feasibility Analysis This step involves evaluating the expected cost of resources needed to execute the project and compare these to expected benefits. At the start of the project a plan of the resources required to undertake the project activities is constructed. If there is a limit on the amount of resources available then the project completion date may have to be set to ensure there resources are not overloaded. This is a resource-constrained approach. Alternatively the need to complete the project by a specific date may take precedence. In this case an alternative source of resources may have to be found, using subcontractors for example, to ensure timely project completion. This is called a time-constrained approach. Once a plan has been constructed it is necessary to
calculate estimates for the time and resources required to undertake each
activity in the project. Statistical methods should be used when the project
is large (and therefore complex) or novel. This allows the project team to
replace a single estimate of duration with a range within which they are
confident the real duration will lie. This is particularly useful for the
early stage of the project when uncertainty is greatest. The accuracy of the
estimates can also be improved as their use changes from project evaluation
purposes to approval and day to day project control. The PERT approach allows
optimistic, pessimistic and most likely times to be specified for each task
from which a probabilistic estimate of project completion time can be
computed. |
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11.1.2. |
This stage estimated the amount and timing of resources needed to achieve the project objectives. The project management method uses a systems approach to
dealing with a complex task in that the components of the project are broken
down repeatedly into smaller tasks until a manageable chunk is defined. Each
task is given its own cost, time and quality objectives. It is then essential
that responsibility is assigned to achieving these objectives for each
particular task. This procedure should produce a work breakdown structure
(WBS) which shows the hierarchical relationship between the project tasks. |
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11.1.3. |
Control This stage involves the monitoring the progress of the project as it executes over time. This is important so that any deviations from the plan can be addressed before it is too near the project completion date to take corrective action. The point at which the project progress is assessed is termed a Milestone. The type of project structure required will be dependent on the size of the team undertaking the project. Projects with up to six team members can simply report directly to a project leader at appropriate intervals during project execution. For larger projects requiring up to 20 team members it is usual to implement an additional tier of management in the form of team leaders. The team leader could be responsible for either a phase of the development or a type of work. For any structure it is important that the project leader ensures consistency across development phases or development areas as appropriate. For projects with more than 20 members it is likely that additional management layers will be needed in order to ensure that no one person is involved with too much supervision.\ The two main methods of reporting the progress of a
project are by written reports and verbally at meetings of the project team.
It is important that a formal statement of progress is made in written form,
preferably in a standard report format, to ensure that everyone is aware of
the current project situation. This is particularly important when changes to
specifications are made during the project. In order to facilitate two-way
communication between team members and team management, regular meetings
should be arranged by the project manager. These meetings can increase the
commitment of team members by allowing discussion of points of interest and
dissemination of information on how each team’s effort is contributing to the
overall progression of the project. |
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11.2. |
Network Analysis This section describes the major stages in the
construction of the critical path method (CPM) and program evaluation and
review (PERT) project networks. The stages in network analysis are now
outlined. |
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11.2.1. |
Identifying Project Activities In order to undertake network analysis it is necessary to break down the project into a number of identifiable activities or tasks. This enables individuals to be assigned responsibility to particular tasks which have a well-defined start and finish time. Financial and resource planning can also be conducted at the task level and co-ordinated by the project manager who must ensure that each task manager is working to the overall project objectives and not maximising the performance of particular task at the expense of the whole project. Activities consume time and/or resources. The first stage
in planning a project is to break down the project into a number of
identifiable activities with a start and end. Performance objectives of time,
cost and quality can be associated with each activity. The project is broken
down into these tasks using a work breakdown structure. This is a
hierarchical tree structure which shows the relationship between the tasks as
they are further sub-divided at each level. |
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11.2.2. |
Estimating Activity Durations The next stage is to retrieve information concerning the
duration of the tasks involved in the project. The can be collated from a
number of sources, such as documentation, observation, interviewing etc.
Obviously the accuracy of the project plan will depend on the accuracy of
these estimates. There is a trade-off between the cost of collecting
information on task duration’s and the cost of an inaccurate project plan. |
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11.2.3. |
Identifying Activity Relationships It is necessary to identify any relationships between tasks in the project,. For instance a particular task may not be able to begin until another task has finished. Thus the task waiting to begin is dependent on the former task. Other tasks may not have a dependent relationship and can thus occur simultaneously. Critical path diagrams are used extensively to show the activities undertaken during a project and the dependencies between these activities. Thus it is easy to see that activity C for example can only take place when activity A and activity B has completed. Once a network diagram has been constructed it is possible to follow a sequence of activities, called a path, through the network from start to end. The length of time it takes to follow the path is the sum of all the durations of activities on that path. The path with the longest duration gives the project completion time. This is called the critical path because any change in duration in any activities on this path will cause the whole project duration to either become shorter or longer. Activities not on the critical path will have a certain amount of slack time in which the activity can be delayed or the duration lengthened and not affect the overall project duration. The amount of slack is a function of the difference between the path duration the activity is on and the critical path duration. By definition all activities on the critical path have zero slack. It is important to note that there must be at least one critical path for each network and there may be several. There are two methods of constructing critical path
diagrams, Activity on Arrow (AOA) were the arrows represent the activities
and Activity on Node (AON) were the nodes represent the activities. The
issues involved in which one to utilise will be discussed later. The
following description on critical path analysis will use the AON method. |
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11.2.4. |
Drawing the Network Diagram For the activity-on-node notation each activity task is represented by a node with the following format. Thus a completed network will consist of a number of nodes connected by lines, one for each task, between a start and end node. Calculating the Earliest Start/Finish times (forward pass) From the duration of each task and the dependency
relationship between the tasks it is possible to estimate the earliest start
and finish time for each task as follows. You move left to right along the
network, forward through time. |
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1. |
Assume the start (i.e. first) task begins at time = 0 |
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2. |
Calculate the earliest finish time where : Earliest Finish = Earliest Start + Duration Calculate the earliest start time of the next task where:- Earliest Start = Earliest Finish of task immediately before If there is more than one task immediately before take the task with the latest finish time to calculate the earliest start time for the current task. Repeat steps 2 and 3 for all tasks Calculating the
Latest Start/Finish times (backward pass) It is now possible to estimate
the latest start and finish time for each task as follows. You move right to
left along the network, backward through time. |
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1. |
Assume the end (i.e. last) task end time is the earliest
finish time (unless the project end time is given). |
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2. |
Calculate the latest start time where : - Latest Start = Latest Finish - Duration Calculate the latest finish time of the previous task where:- Latest Finish = Latest Start of task immediately after. |
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If there is more than one task immediately after take the task with the earliest start time to calculate the latest finish time for the current task. Repeat steps 2 and 3 for all tasks Calculating the slack/float times The slack or float value is the difference between the
earliest start and latest start (or earliest finish and latest finish) times for
each task. To calculate the slack time |
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1. |
Slack = Latest Start - Earliest Start OR Slack = Latest
Finish - Earliest Finish |
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2. |
Repeat step 1 for all tasks. Identifying the Critical Path Any tasks with a slack time of 0 must obviously be
undertaken on schedule at the earliest start time. The critical path is the
pathway connecting all the nodes with a zero slack time. There must be at
least one critical path through the network, but there can be more than one.
The significance of the critical path is that if any node on the path
finishes later than the earliest finish time, the overall network time will
increase by the same amount, putting the project behind schedule. Thus any
planning and control activities should focus on ensuring tasks on the
critical path remain within schedule. |
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11.2.5. |
Identifying Schedule Constraints - Gantt Charts Although network diagrams are ideal for showing the relationship between project tasks, they do not provide a clear view of which tasks are being undertaken over time and particularly how many tasks may be undertaken in parallel at any one time. The Gantt chart provides an overview for the Project Manager to allow them to monitor project progress against planned progress and so provides a valuable information source for project control. To draw a Gantt Chart manually undertake the following steps : |
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Draw a grid with the tasks along the vertical axis and the
time-scale (up to the project duration) along the horizontal axis. |
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Draw a horizontal bar across from the task identifier
along the left of the chart starting at the earliest start time and ending at
the earliest finish time. |
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Indicate the slack amount by drawing a line from the
earliest finish time to the latest finish time. |
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11.2.6. |
Project Crashing The use of additional resources to reduce project completion time is termed crashing the network. This involves reducing overall indirect project costs by increasing direct costs on a particular task. One of most obvious ways of decreasing task duration is to allocate additional labour to a task. This can be either an additional team member or through overtime working. To enable a decision to be made on the potential benefits of crashing a task the following information is required. |
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The normal task duration |
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The crash task duration |
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The cost of crashing the task to the crash task duration
per unit time |
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The process by which a task is chosen for crashing is by
observing which task can be reduced for the required time for the lowest
cost. As stated before the overall project completion time is the sum of the
task durations on the critical path. |
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