PROJECT PLANNING TOOLS GANTT CHARTS The Gantt chart is a popular tool for planning and scheduling simple projects. It enables a manager to initially s...
PROJECT PLANNING TOOLS GANTT CHARTS The Gantt chart is a popular tool for planning and scheduling simple projects. It enables a manager to initially schedule project activities and then to monitor progress over time by comparing planned to actual progress. To construct a Gantt chart, major activities and their duration and the sequence needs to be identified. Horizontal bars are drawn for each activity along a time line. The obvious advantage of the Gantt chart is its simplicity and therefore it has become very popular. Identify the tasks required to make a cup of tea & the correct sequence ACTIVITY
DURATION (minutes)
Gantt Chart for making a cup of tea
Time (mins)
Gantt Chart for a wedding
Time
Work Breakdown Structure WBS is a hierarchical decomposition of the project into phases, deliverables and work packages
Exercise (Group) Construct a WBS and Gantt Chart for a wedding ceremony
PERT (Program Evaluation and Review Technique) For each activity in PERT we must specify an optimistic time, a most probable time and a pessimistic time estimate. We then use these three time estimates to calculate an expected completion time and variance for each activity. We can use the formula: t
=
a + 4m +b 6
and
v
=
where a
=
optimistic time for activity completion
b
=
pessimistic time for activity completion
m
=
most likely time for activity completion
t
=
expected time of activity completion
v
=
variance of activity completion time
b–a 6
2
EXAMPLE
Compute the expected times and variances of completion for each activity based on the following time estimates: ACTIVITY
a
b
(time
m
(time
in
(time in weeks)
weeks)
weeks)
a+4m+b
t
in
b-a 6
2
SQUARE ROOT
Clear site
3
4
5
24
4
2/6
0.111
Dig foundation
1
3
5
18
3
4/6
0.198
Pour concrete
5
6
7
36
6
2/6
0.012
Build walls
6
7
8
42
7
2/6
0.012
EXERCISE 2 – PERT The following data was collected: Activity 1
CRITICAL PATH METHOD (CPM) CPM (Critical Path Method) is a widely used techniques for planning and coordinating large-scale projects. According to Heizer they follow six basic steps: (i)
Define the project and prepare the work breakdown structure.
(ii)
Develop the relationships among activities together with their sequence.
(iii)
Compile the network connecting all activities.
(iv)
Assign time or cost estimates to each activity.
(v)
Calculate the longest time path through the network. This is known as the critical path.
(vi)
Use the network to help plan, schedule, monitor and control the project.
Finding the critical path is a crucial step in controlling the project. The activities on the critical path represent the tasks that will delay the entire project unless they are completed on time. PERT and CPM answer the following questions: (i)
When will the entire project be completed?
(ii)
What are the critical activities – the ones that will delay the project if they are late?
(iii)
What are the non-critical activities – the ones that can run late without delaying the completion of the project?
(iv)
What is the likelihood that the project can be completed by a specific date?
(v)
At any particular time, is the project behind, on or ahead of schedule?
(vi)
Are we meeting our budget?
(vii)
Are there sufficient resources to complete the project?
(viii) If the project is to be completed in a shorter time, what would it cost us?
THE NETWORK DIAGRAM The network diagram of a project shows sequential relationships by use of arrows and nodes (circles). The arrows represent the project activities and the nodes (circles) indicate events. The activities are project tasks that consume resources and or time and the nodes (circles) indicate the starting or finishing of events. A path is a sequence of activities that leads from the starting node to the finishing node. The critical path is the longest path of the network. Critical activities are the activities on the critical path. Dummy activities are inserted into the network to maintain the logic and sequence of the network – they consume no time or resources.
C 4
F 3
A 6
H 4
D 2
G 6 B 7 E 8
Required: 1. Identify paths through the network 2. Identify the Critical Path (longest path through the network) 3. Calculate the expected completion time for this project.
Exercise 1 Activity A B C D E F G H I J K
Predecessor A B C,D B F B H H E
Duration (days) 4 5 6 7 2 9 4 3 8 8 7
CALCULATE RESOURCES OFF THE NETWORK DAIGRAM
Exercise 1 The following table represents a project you are working on: ACTIVITY A B C D E F G H I J
Construct the network and then calculate the daily labour requirements and assuming each worker, works an 8 hour day and is paid R 27.50 per hour; Calculate the daily labour cost.
Exercise 2 Activity A B C D E F G H I J
Predecessor B A,D C E F,G E H,I
Duration 2 1 3 2 3 5 2 1 2 1
Labour Required 6 7 7 8 9 11 15 10 6 8
Calculating Early Start/ Early Finish/ Late Start/ Late Finish
