What is a Project Schedule?
A project schedule is basically a model or graphical representation of activities. This schedule is developed by analyzing different type of project information like activities to be performed, their estimated duration, relationship between activities, project constraints, lags and leads etc. A project schedule is a key document which is used to plan, monitor and control activities for successful completion of a project. You can use one of several scheduling softwares to develop a schedule like Primavera P6 and MS project. However basic steps to create a schedule will remain same and need to be properly understood. There are six basic steps to create a project schedule. Let us discuss these steps one by one.
Step 1: Understand your Project
First and a very important step in developing a project schedule is to understand your project thoroughly. This is a step which is important but often neglected. Remember, you cannot make a good schedule unless you have a complete picture of the project in your mind. What I suggest is, if you have 30 days to develop a schedule then spend 25 days in just understanding it. Yes, you have read it correctly. 25 days. This
will make such a picture of the project in your mind that you can recall every single detail of it. And now, developing a schedule will be matter of just 4 to 5 days. But if your boss has told you to make a schedule in 30 days and you are so excited that you started scheduling on Primavera P6 or MS Project the same day, believe me you are going to loose.
Now the question is, how to do this conception work? Very simple. Go through with every document and every detail of the project that is available to you. Not only scope documents but also with cost, risk or other type of documents available to you. Each type of document will help you in a way or another. These documents may include project charter, bill of quantities, contract documents, general and particular conditions of contract, tender documents, drawings, specifications etc.
Step 2: Make Work Breakdown Structure (WBS)
Now that you have clear understanding of your project, you can divide this project into smaller and manageable parts. This breaking down a project into smaller parts or work packages is called Work Breakdown Structure or WBS. WBS is used to organize project activities, summarize project data and in Primavera P6 it is also used to control access of schedulers for different work packages.
WBS is a key to a good schedule, so, spend some time on it. For example, if you are constructing a 2 storey house then you can divide your work as Foundation Works, Ground Floor Works, First Floor Works and Roof Works. Then you can subdivide these areas of works by nature of work. For example, Foundation Works can be subdivided into Earthworks and Structure Works. Ground Floor Works can be subdivided into Structure Works, Architecture Works, Electrical Works, Plumbing Works and HVAC Works. HVAC stands for Heating, Ventilation and Air Conditioning. Same subdivision can be done for First Floor Works and Roof Works. Its a good practice to subdivide a project up to 4 levels of WBS. The lowest level of WBS will contain activities.
Step 3: List down Project Activities
After making WBS, now its time to list down each and every activity under its respective WBS element. For example, Earhworks may include activities such as Excavation for Foundations, Termite Proofing of Excavation Trenches and Backfilling etc. Note that it is not necessary to list activities in the order of their occurrence. You just have to list. Sequence of activities will be determined later.
There are some points which need to be practiced while listing activities. Such as, they should represent sufficient volume of work to avoid large number of activities. Also these should be listed such that duration of a single activity spans between 7 to 30 days. Each activity is assigned an ID to represent these activities. In addition, milestones are also created which are representation of start or finish of some major part of the work. For example, start of earth works is a start milestone and finish of ground floor works is a finish milestone.
Step 4: Determine Activity Resources and Durations
After listing down activities, now its time to estimate resources and durations. Activity resources and activity durations are interlinked with each other. In normal practice, durations are estimated from minimum resource requirement of the activity and if time estimates are large or unacceptable, then resources are increased to shorten duration of activities.
In repetitive projects, like construction projects, resources productivity is known and available in the form of a Productivity Chart. This chart contains information that which resource will work for how many hours in what conditions to give what amount of output? For example, abc excavator will work 8 hours in normal ground conditions to excavate 15000 cubic feet (Cft) of soil. So if we have to excavate 45,000 Cft of soil then this means it should take 3 days to excavate with abc excavator. You see that we have determined both the resources and duration estimate for this activity. It is also important to consider work days in a week, holidays and risk factors like rains etc while estimating durations of activities.
Step 5: Determine Activities Sequence
Now the relationship between activities will be determined. Relationships can be of four types; Finish to Start (FS), Start to Start (SS), Finish to Finish (FF) or Start to Finish (SF). For each activity, first its successor/s will be identified and then one of these four relationships will be given to these successor/s. Successor is an activity whose start or finish is controlled by some other activity or predecessor. For example, foundations will be built after excavation for foundations. In this example excavation is the predecessor, building of foundations is the successor and there is Finish to Start relationship between them. Finish to Start means, successor activity cannot start until predecessor activity has finished.
Sometimes, sequencing of activities is done before estimating their durations. This is also a good practice in order to avoid resource conflicts, however its confusing. With durations estimated you will have a more clear picture of the project which will help activity sequencing.
Step 6: Develop Schedule
Now its time to analyze all the information that we have till now and to develop a schedule out of it. Schedule gives important information like start and finish dates of activities, total and free floats, critical path etc. In CPM, scheduling is done by forward pass and backward calculations which gives early start, early finish, late start and late finish of activities. Total float is then calculated by subtracting early finish from late finish or early start from late start (LF-EF or LS-ES). Longest path is calculated by adding durations of all possible paths of network diagram. In Primavera P6, it is not needed to do this intense calculation. After step 5, you need to press a button and whole scheduling is done for you using CPM technique.
A schedule is an important document as it represents project plan. This includes start and finish dates of activities, their relationships, total and free floats of activities and critical path. Scheduling involves certain steps like understanding a project, making WBS, listing activities, estimating resources and duration of activities, sequencing activities and analyzing this whole data to finally develop a schedule. Scheduling for large and complex projects should be done on scheduling softwares like Primavera P6 and MS Project.
Read Also: Primavera P6 VS MS Project