Friday, August 11, 2006

Chapter 6: Developing a project plan (continue)
The project network

Last week I learned about AOA and bar chart of the project network. In this week, we start with a question: if you want to decrease a project time, what will you do? The first, I tried to reduce the critical path time, but some activities are fixed, we can’t do. We can do by divide of some activities by logistic thinking (activities on node need logic), use of lags time: start to start relation (SS), or finish to start relation (FS). Form example: the pipeline project, it has 5 activities, mobilize and survey (MS), excavate trench (ET), purchase pipe (PP), lay pipe (LP), and backfill (BF). We can divide ET to 3 sub activities, after finish the first sub activities, we can start LP, use of lags time or start to start, SS = 2, it means after ET start 2 days, LP will start, we no need to wait until SS finish (finish to start). SS can reduce the project time 3 days.
We can reduce the project time by use of lags:
FF: Finish to Finish
SF: Start to Finish
SS: Start to Start
Hammock Activities mean the activity span over a segment of a project, use to aggregate section of the project to smooth the right amount of detail for specific sections
Basic rules of project network
Networks flow from left to right.
An activity cannot begin until all of its activities are complete. (ES)
Arrow indicates precedence, flow, can cross over.
Activity number: a unique number, and greater than its predecessors.
No looping.
No condition
Use common start and stop nodes.

The first I tried to do an AON by Microsoft Project, after finish, I read basic rules of project network, and found some mistake, such as: number of activities that smaller than its predecessors (I adjust a sequence again, make a sequence follow a number in right hand must bigger than left hand), some path not connect to their predecessors, and some activities are same name but different group (use indent). I think we have to understand and follow the basic rules in developing project network; the rules can help project manager and participants easy to understand the network.

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