Bar schedule (Gantt chart)
One of the most widespread graphical representations of scheduling is the bar chart schedule. Without a construction schedule, it is impossible to organize construction. We don't know when to request concrete delivery or when the specialized trades should arrive. Besides these, it also provides important information for making decisions related to organization.
If you search online, you will find two types of bar chart schedules. One is static, the other is dynamic. Their representation is similar, but their subsequent modification and optimization differ significantly.
Static Schedule
This is well-suited for smaller workflows, as it is easy to create – even with a hand drawing or using Excel – but its modification is cumbersome.
Below you can see an example of this, where I have divided the construction into larger workflows. Above it, you will also find a resource diagram.
It clearly separates how processes should follow each other; however, if one of them falls behind, or if additional work needs to be inserted in the meantime, the entire diagram must be redrawn, just as with resource optimization.
(By resource optimization, we mean shifting some workflows, or calculating with a longer activity duration to avoid overloading the work area. For example: to prevent a situation where 50 people are working one day and only 10 the next, as this can affect the parameters of supporting units.)
Once we've seen how cumbersome it is to update a static bar chart schedule, we will appreciate the dynamic bar chart schedule much more.
Dynamic Schedule
We represent it similarly to the static bar chart schedule, but we create logical connections between activities. I write about these connections in another article, but you can read the essence here.
In a dynamic schedule – similarly to a static one – we define the activities and their durations, but we create connections between the processes. Then, a program calculates the project's lead time for us and indicates the tasks that must be completed at a given time to prevent the project from falling behind (critical path).
How does this help us in updating and modifying the schedule? If any modification occurs (resource optimization, inclusion of additional processes), the program recalculates the lead time for us. What programs can be used? There are several. The widely used and professionally applicable one is Microsoft Project, but among free programs, I recommend GanttProject, which has worked very well for me. Of course, it has its flaws and not everything can be done in it, but for a free program, it is quite usable.
Summary:
For any larger construction project, it is highly recommended to create a schedule to determine what needs to be delivered and completed by subcontractors and when. However, to make it usable and to define the workflows, we need detailed plans and appropriate professional knowledge. Once we are done and using it, we realize how useful such a calendar is.
Sources:
YBL lecture notes
personal experience