A good schedule should be structured in a way that is easy to understand, but still provides enough detail for experienced personnel to get useful information. The following steps to create a good schedulecan be distinguished:
- Define the work structure (WBS)
- Define milestones and activities.
- Define the logic between activities.
- Define resources and work.
- Define work time (calendar)
- Analyze the schedule.
Work structure (WBS)
One of the fundamental aspects when creating a schedule is the grouping of activities into work packages (WBS. This organization ensures that activities are structured in a way that eases their management and control. The objective is to make large projects more manageable by breaking them down into manageable work packages and processes.
Two types of WBS can be distinguished, the functional and the deliverable type. While hybrid structures do exist, they are often based mainly on one of these two types.
- Functional WBS: This type divides the project into phases or steps related to the various disciplines required for project completion. Organizing activities this way aligns the schedule with the project’s construction logic and the steps to be followed. For example, phases could include initiation, engineering, planning, execution, control, and commissioning. Within each phase, further subdivisions can be made based on deliverables or responsible individuals.
- Deliverable WBS: This approach divides the project into the physical deliverable components essential for project completion. It aids in visualizing the overall project scope and the relationships between deliverables.
The WBS can have various levels depending on the project’s scope and size. Work packages represent the most detailed level within the WBS, requiring multiple work packages to complete a single element of the WBS. These work packages are structured to include all the activities necessary for completing the higher-level elements of the WBS.
Work packages should be formulated in a way that clearly illustrates the actions to be taken on specific elements. Earned value data is typically captured at this level to ensure proper tracking of project status.
Using activity codes can be highly beneficial for quick and easy grouping. This allows for the creation of different activity views. For instance, if a deliverable-based WBS is defined, appropriate codes should be assigned to visualize activities by processes and vice versa. This flexibility enhances the efficiency of schedule management and reporting.
Definition of activities
The activities are the last level in the planning of a project and therefore are the basic elements of a schedule. All activities must have at least:
- ID – It is the alphanumeric code that uniquely identifies each activity within the schedule. IDs are not random! In a good planning program each activity should be coded.
- Name – The name of the activity should be brief and concise but descriptive so as to explain as best as possible what the activity consists of.
- Duration – The duration of an activity can be entered by the technician in the case of activities not conditioned by effort, or calculated by the software itself based on the work to be done and the allocation of resources. In Primavera P6 hours are the basic unit of duration, if days or weeks are entered, a number of hours will be recalculated based on the parameters entered in the calendar. Very long activity durations should be avoided.
- Calendar – All activities have a calendar associated, in which the working hours, working days are defined… In the case of MS Project, if no specific calendar is assigned, the software will take the project calendar.
- Predecessor and successor -All activities except the first and last must have a predecessor and successor so that all dates are based on relationships and not on constraints.
- Resources – All activities must be associated with some resource, be it the person responsible, material, machinery, or the necessary human resources. The definition and allocation of resources requires a detailed analysis of the amount of work to be done or material to be consumed. Resources allow you to calculate the duration of activities, track project costs and generate progress curves (man hours).
- Codes – It is advisable to define and assign codes to effectively group and filter activities throughout the project. The Global Activity Code should be used when those same codes are going to be used in several projects other than the company’s portfolio and the Project Activity Code for those codes that are only applicable for one schedule.
In the case of payment milestones and contractual milestones, they must always be present in the schedule (there are cases in which the milestones are marked first and then the schedule is requested).
Define the logic
Logic is an essential factor in a properly designed schedule, it must be ensured that the logic is accurate and correct. Only Hard logic is valid within a program, since any other form of logic can reduce the effectiveness of the tools used and require modifications during execution. There are four types of relationships, with Finish-to-Start being the most common and easiest to understand and apply. Three types of logic can be distinguished:
- False Logic – used to arbitrarily modify the sequence of activities in a program to achieve preconceived results on the start and/or end dates of an activity. For example, shipments should start when the civil work is finished.
- Soft logic – logic used to organize activity dates based on work preference. This type of relationship should be avoided for everything on the critical path of the project, otherwise there is a risk that it will change easily. For example, the installation of a building facade must be finished before the installations can begin.
- Hard Logic – Generates rigid and valid links between activities. For example, the nacelle of a wind turbine cannot be installed without having completed the tower.
Analysis of the schedule
Upon completing the schedule, a critical evaluation is necessary to determine if the planned sequence aligns with the collective experience and knowledge of the project’s technicians. The main method to analyze a schedule is the critical path method, the critical path must be examined by questioning all relationships and durations of critical activities.
Once the critical path has been reviewed, it is necessary to check that there are no activities without predecessors or successors and in the event that there are activities with restrictions (constrains) on the start or end date, check if it is possible to adjust the relationships to avoid that restriction.
Contractual obligations must always be fulfilled and in case of not doing so, it is necessary to check where the problem is. If the date of any contractual milestone is not met and it has been verified that the durations, calendars and constructive logic are correct, it is necessary to communicate to the rest of the team that according to the planning the target date will not be reached. In that case, the allocation of resources and logic will have to be re-evaluated.
Every planning engineer should define the steps to create a good schedule that works best for them.