Deciding which type of schedule is right for your subcontracting business is a crucial element to your success as a subcontractor. In fact, the success of all your construction projects relies heavily on a project’s schedule. In this article, we will go over several different methods of scheduling and schedule representation methods so that you can produce schedules that best align with your company’s construction process.
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What Is Construction Scheduling?
Construction scheduling is a comprehensive plan for completing a construction project by a given deadline. Different schedules are used for different construction projects, but every construction schedule should cover how, when, and what will be used to accomplish construction activities by specific dates.
What Is A Construction Scheduler?
Construction schedulers manage when, where and how resources are used on a construction project. Construction schedulers may also partake in various roles and responsibilities like project management and construction estimating. Companies often have dedicated schedulers or teams of construction schedulers because creating construction schedules is no simple task. For small construction projects, you may be able to finish a schedule in a few hours or days, but construction schedules may take months or years to complete for large, complex construction projects.
Why Do We Need Construction Schedules?
Construction schedules form the basis of all construction activities on a construction project. Whether your company uses Gantt charts, an excel spreadsheet, or a whiteboard to create schedules, your construction schedule should be a primary driver of your construction process.
Below are some of the main reasons for scheduling construction projects:
- Schedules tell you when and where you need resources.
- Delays are going to happen, but being able to look at a schedule and quickly determine ways to mitigate delays is essential.
- Schedules allow you to align your work with the GCs schedule, along with other subcontractor schedules. You can’t have two contractors working in the same location at once. By creating a schedule, you can visualize issues before they arise.
- Without a schedule, you can’t analyze your productivity rates on projects, which can have a direct impact on your future bidding and profit margins.
Types of Construction Schedules
Critical Path Method (CPM)
The critical path method is the most commonly used scheduling method for construction projects. The CPM creates a schedule based on critical activities, which must be completed before another activity can begin. Once critical activities are identified, they are scheduled in sequence to determine the least amount of time a construction project can be completed. Pouring a concrete foundation would likely be a critical activity on a construction project because you can’t start erecting steel if you don’t have a concrete foundation already poured.
Last Planner System (LPS) / Pull Planning
Pull planning is a construction scheduling technique that establishes vital project milestones, like the project completion date, then works backward to outline the steps to achieve each milestone quickly and efficiently. The defining features of pull planning are strong collaboration and the backward timeline. Looking at the project “backward” illuminates how earlier tasks ultimately impact key milestones.
Resource oriented schedules are used when there are limited resources available for a project. Resource oriented schedules are driven by labor and equipment constraints rather than by construction materials. That being said you can still build in material lead times and delivery milestones into your resource oriented schedules. Resource oriented scheduling is especially popular for subcontractors whose primary constraint is construction crews and equipment. Suppose there are multiple projects spread across a city occurring simultaneously. In that case, it is essential to know if you will have the resources available to accommodate the work, making resource oriented schedules a good option for subcontractors. Resource oriented schedules most commonly include elements of a CPM schedule.
Program Evaluation and Review Technique (PERT)
Construction schedulers use PERT to create an initial schedule for a complex project. The process identifies durations of tasks, critical activities, and task dependencies to truly analyze a project before it begins. Every task is given three durations:
- Optimistic Time (O): The least amount of time you think a task will take to be completed.
- Pessimistic Time (P): The most amount of time you think a task will take to be completed.
- Most Likely Time (M): How long you think a task will actually take to complete.
PERT scheduling is used instead of CPM scheduling if the duration of tasks isn’t straightforward. That is why PERT scheduling is a good option at the beginning of a project when you don’t know precisely how long activities will take. The PERT schedule may eventually become a schedule that resembles the CPM once more information can be determined about construction tasks.
Line of Balance
Line of balance schedules are very uncommon but are sometimes used when a construction project consists of highly repeatable and similar tasks. Line of balance schedules are created using crews, and production rates, that are then planned out over a certain period. Line of balance schedules are most commonly used for roadways, pipes, and other horizontal construction projects. For repeated work activities, they allow for intensive cost and time optimization, and it is also much easier to change and update line of balance schedules.
Quantitative Scheduling (Q Scheduling)
Quantitative scheduling, also known as Q scheduling and queue scheduling, uses bar charts to visualize resource quantities and the locations in which the resources will be used. Q scheduling is one of the least common scheduling methods in construction. It is only used when tasks are repeated, but variable quantities of resources are used.
Visual Representation of Schedules
A Gantt chart is a visual representation of project timelines. Gantt charts are very common in construction, and while they are considered a scheduling method by themselves, Gantt charts are also a common way to display LPS, CPM, Resource Oriented, PERT, Line of Balance, and Q schedules.
A bar chart is a graphical representation of scheduling activities. It is the simplest way to display a construction schedule. The bar chart is created by the activities’ start and end date plotted against the project’s timescale.
Percentage Completion vs. Time Graph
A percentage completion vs. time graph shows what percentage of the project is completed in relation to the duration. This is one of the most commonly used graphs to analyze the progress of a construction project.
Resource Usage vs. Time Graph
Resource usage vs. time graphs take the current man-hours used and compare that to the total man-hours on the project, then compare that to the project’s duration. Resource usage vs. time graphs can be analyzed to make sure resources are being used at the rate that you scheduled for. These graphs will tell you why there are cost overruns due to labor.
Software for Construction Scheduling
Construction scheduling is one of the most challenging parts of managing projects, but scheduling software has made the process significantly easier. These are just a few of the construction scheduling options available:
- Microsoft Project
- Autodesk Construction Schedule Manager
- Project HQ – By Foundation Software
Implementing A Scheduling System
If you don’t already have a scheduling system in place, now is the time to create one. It doesn’t matter if you’re working on one project or 20 projects, having a process to schedule construction projects is essential to being able to grow your business and take on more projects.