What is the Line of Balance/Linear Scheduling Method?
-Line of Balance (LOB) scheduling or Linear scheduling (LSM) is a method that shows the repetitive work that may exist in a project as a single line on a graph. Unlike a Gantt (Bar) Chart, which shows the duration of a particular activity, a LOB graph shows the rate at which the work that makes up all of the activities has to be undertaken to stay on schedule, the relationship of one process or trade to the subsequent trade or process is defined by the space between the lines. If one group is running behind the time schedule, it will impact on the following group & this is shown by the lines intersecting.
-LOB is a simple diagram to show the time and location at which a certain crew will be working on a given operation.
-Line of Balance is a good visual tool that lets us see if a construction program can be achieved with the minimum waiting time between tasks
The purpose of the Line of balance or Linear Scheduling Method is to ensure that the many activities of a repetitive production process stay “in balance” that is, they are producing at a pace which allows an even flow of the items produced through a process & at a speed compatible with the goals set forth in a plan.
The advantages of Line of Balance :
- The linear scheduling method shows Clearly the amount of work taking place in a certain area at a specific time of the project.
- LSM has the ability to show & optimize the resources used for a large number of repeated activities, executed in several zones or locations.
- It’s Easy for optimization analysis of cost and time analysis because of all the information available for each activity in the project.
- Ease of setup and its superior presentation & visualization.
- Easier to modify, update and change the time schedule.
- Better managing of all the various main contractors/sub-contractors in the project.
- It allows for simpler resource management & resource optimization functions.
- Visualization of productivity & location of crews.
- It allows construction project/project managers to see, in the middle of a project, whether they can meet the schedule if they continue working as they have been.
- LOB is a Good Visual tool that lets us see if a construction program can be achieved with the minimum waiting time between tasks
Line of Balance Calculation
- The goal of using the Linear scheduling method (LSM) is to achieve a resource-balanced schedule by determining the proper crew size and number of crews to employ in each repetitive activity.
- This is done such that:
1.the units are delivered with the rate that meets a pre-specified deadline
2.the logical CPM network is respected for each unit
3.crews’ work continuity is maintained.
- The analysis also involves determining the start & finish times of all activities in all units and the crews’ assignments.
Types of Diagrams Used in LOB
- Production Diagram: It shows the relationships between activities for a single unit.
- Objective Diagram: Used to plot the actual or planned number of units produced vs. time.
- Progress Diagram: Shows the number of units for which the activity has finished.
Drawing LOB Schedule
Line of Balance Calculation
The CPM-LOB formulation involves:
- Crew synchronization
- Calculating resource needs
- Drawing the LOB schedule