Table of Content for Project Schedule & Techniques–
- What is Project Schedule?
- Why use a Project Schedule?
- Steps of Project Scheduling
- Linking of Activities
- Tools of Project Scheduling
- Techniques of Project Scheduling- CPM & PERT
What is Project Schedule?
A project schedule is a list of work activities to be done for the completion of the project arranged in a logical and sequential manner with a specified timeline. The project schedule aligns the scope and cost of the project in a timeline. It is an important part of project planning and management.
The project planning helps in defining the methodologies and procedures and the schedule sets them in the timeline. Thus, in broad terms, it can be said that the planning answers the ‘what’ and ‘how’ aspects whereas the project schedule answers ‘when’ and ‘who’.
A project schedule is made on the assumptions. The assumptions are estimated duration of the activities, inter-dependency of the activities, availability of resources, allocation, and leveling of the resources, time constraint, budget constraint, etc. The overall project completion timeline is based on all of the above-mentioned assumptions. The project timeline can be altered by changing any of these assumptions.
Why use Project Schedule?
It helps in achieving the following objectives-
- Project Schedule defines the work activities in a logical manner; thus, it makes the project run smoothly.
- The commitment of the project timeline to stakeholders.
- Planning of resources. The what, when, where, how much, who for a resource can be decided.
- Optimum utilization of resources. The activities are scheduled in such a way that the resources can be utilized to its’ full potential.
- Cashflow projections.
- Identification of occurrence of risks and mitigation plans.
- Monitoring and reporting. The schedule can be used for tracking the work progress. Weekly, fortnightly, or monthly targets and progress reports can be generated.
- Prevention of delay. If the project is getting delayed then it can be brought back on track by crashing activities or rescheduling the activities.
Steps of Project Scheduling
The project schedule should be DCMA guideline compliant. The steps of making a project schedule are as follows-
- Identifying the scope of the project, objective, project start date, mobilization time, working and non-working days, etc.
- Creating a Work Breakdown Structure (WBS). The WBS of a project is the breakdown of the project into measurable, easily estimated, and deliverable activities.
- Define the interdependency of the activities. This step helps in linking activities to each other. It determines the time-behaviour of activity with respect to another activity.
- Estimation of resources. The estimation of resources should be done keeping in mind the availability of the resources, cost-effectiveness, work-space constraint, etc.
- Estimation of the duration of activities. The duration estimation of the activities is to be done as per the earlier estimated resources. It is a very important step as the under-estimation of the duration can lead to delay in the project and over-estimation of the duration can lead to underutilization of the resources.
- Monitoring & controlling the schedule. This step continues until the completion of the project. Target setting, progress reporting, mitigation to delay, mitigation of risks, planning for resource mobilization when required, etc. come under this step.
Linking of Activities in a Project Schedule-
The project activities can be linked with each other by following-
- Start to Start (SS)- It is used when two activities can be started simultaneously.
- Finish to Finish (FF)- It is used when two activities are to be finished at the same time.
- Finish to Start (FS)- FS is used when an activity starts when another activity ends.
- Start to Finish (SF)- SF is used when an activity finishes when another starts. It is rarely used.
Tools of Project Scheduling-
The task lists are the simplest method of project scheduling. The tasks to be performed to complete the project are documented. The tasks are documented for each resource separately. It is a feasible method for small scale projects.
The overall timeline of the project can’t be defined in this method. With the increase in the scale of the project, the activities become complicated due to inter-dependencies and hence this method becomes inefficient. Project tracking and collaboration among resources are also very difficult.
It is the most popular tool for the project schedule. Gantt Chart is a horizontal bar chart having activities on the vertical axis and the timeline on the horizontal axis. It is also very helpful in monitoring, controlling, and reporting. The popularity of the Gantt chart is due to its easy adaptability, easy modification, and ability to assign resource(s) to an activity.
The Gantt chart has its’ own set of limitations such as limited collaboration and no versioning.
The calendar is used as a tool for project scheduling for defining the duration of the tasks and overall project timeline. The calendar can be modified as per the project requirement such as working and non-working days and renamed as required. The team members can share the calendars and can visualize the task overlaps. It is easier to modify.
The calendars are limited in defining inter-dependency of the activities.
Techniques of Project Scheduling-
Critical Path Method (CPM)-
The Critical Path Method defines the shortest timeline to complete a project. The flow diagram of the activities is used for defining the timeline. In the flow diagram, the activities of a project are linked to each other with the estimated duration of each activity. The milestones are also defined.
The path representing the sequence of activities defines the different timelines of the project. The longest path is known as the ‘Critical Path’. The duration of the critical path is the minimum duration for a project. The activities lying on the critical path are called critical activities. The delay in critical activities delays the whole project. These activities are said to have zero float.
The critical path method is reliable for the projects which have a well-defined duration for each activity. The infrastructure industry uses CPM frequently.
Program Evaluation & Review Technique (PERT)–
PERT is similar to the CPM except in estimation of the duration of an activity. The PERT uses three-time estimates for an activity. These time estimates are-
Optimistic Time (to)- The minimum possible time to complete an activity.
Most-likely Time (tm)- The most likely duration of activity for completion under normal conditions.
Pessimistic Time (tp)- The duration to complete an activity under the adverse conditions.
The duration taken into account is the weighted average of the above three estimates.
The variance of an activity is defined as-
The project duration is the total duration of critical activities. And the sum of variances of critical activities is the variance of the project.
The PERT is generally used in projects in which the duration of activities cannot be accurately determined. Such projects can be product development, defence system implementation, etc.
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Dive deeper into the project scheduling with this construction project schedule example.