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PROJECT SCHEDULING WITH KNOWN ACTIVITY TIMES 373

Table 9.1 List of Activities for the Souk Al Bustan Shopping Centre Project
Activity Immediate Activity
Activity Description Predecessor Time (weeks)

A Prepare architectural drawings — 5
B Identify potential new tenants — 6
C Develop prospectus for tenants A 4
D Select contractor A 3
E Prepare building permits A 1
F Obtain approval for building permits E 4
G Perform construction D, F 14
H Finalize contracts with tenants B, C 12
I Tenants move in G, H 2
Total 51

There are a few things to note about the diagram. The first is that when you are
drawing the diagram manually it will usually take several attempts before it is right,
particularly with more complex projects. You should always check your diagram to
make sure that the sequencing of activities is correct and that the precedence
structure is correct. Secondly, the length of the arrows does not necessarily corre-
spond to the actual time taken. The length of arrows is determined by how we need
to show the diagram in terms of logical precedence of activities. Thirdly, this type of
diagram is referred to as an activity-on-node diagram (or precedence diagram).
An alternative approach is the activity-on-arrow diagram which is described in
Appendix 9.1. In this chapter we focus on the activity-on-node approach primarily
because this is the approach typically adopted by project management software such
as Microsoft Project.

The Concept of a Critical Path

To facilitate the PERT/CPM calculations, we have modified the project network as
shown in Figure 9.2. Note that the upper left-hand corner of each node contains the
corresponding activity letter. The activity time appears immediately below the letter.

Figure 9.1 Project Network for the Souk al Bustan Shopping Centre

E F
Prepare Obtain
Permits Permits
A D
Prepare Select G
Drawings Contractor Construction

C H I
Start Develop Finalize Tenant Tenants Finish
Prospectus Contracts Move In

B
Identify
New Tenants

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