1. LINEAR BALANCE METHOD & MATRIX SCHEDULE
CHAPTER 3 PART 2
LINEAR BALANCE METHOD & MATRIX SCHEDULE

2. Lines of Balance Scheduling Method
Introduction
LOBSM or Linear Scheduling are planning and scheduling techniques commonly used in construction and manufacturing industries.
Involves repetitive operations.
Linear scheduling methods that allows balancing operations (activities is continuously and efficiently performed in each consecutive unit).
Examples of projects: pavement construction, multi-housing projects, tunnels, railroad tracks and high rise building construction.

3. Introduction LOB in construction offers 2 main advantages:
It allow project managers to see, in the middle of a project, whether they can meet the schedule if they continue working as they have been.
It exposes process bottlenecks, allowing the project manager to focus on those points responsible for slippage.

4. Introduction
LOB scheduling technique based on underlying assumption that the rate of production for an activity is uniform.
Production rate of an activity is the slope of the production line (expressed in terms of units per time).
LOB schedule plotted:
Horizontal axis or X-axis represent Time
Vertical axis or y-axis represent Units or Stages of an activity.

5. Example
A typical project (A Housing Project) consisting of several houses where the same type of work such as foundations, brickwork, roof construction and internal trades are undertaken on each house.
When the activities programmed in a bar chart, the program will look like the example in Fig. 1

6. Example

7. Example Using LOB the same operation will look like in Fig.2
Figure 2: Linear Schedule for Housing Project

8. LOBst Vs. Bar chart
LOB Chart able to summarize a group of similar activities onto one line and consequently a large number of common activities onto a much smaller document.
LOB Chart shows the rate at which the work that makes up all of the activities has to be undertake to stay on schedule.
LOB Chart shows an output relationship between the different operations, not between individual activities.

9. Progress reporting via lob chart
Lob Chart is progressed by plotting on the chart the work achieved to allow for the planned rate of completion of various trades to be compared with the actual.
Rate achieved lower than planned, adjustment needed to increase the output.
Figure 3 show progress of House Construction up to week 12.
The Foundations are on schedule & almost complete
Brickwork and Roof are running behind schedule.
Internal works have not started. (anticipated rate was plotted on the chart & by extrapolation, the first 3 units will be completed 3 weeks late)

11. Linear scheduling methods
Interpretation Of LOB Graph
Location
Quantity of Work
Slope represents rate of progress (e.g. cubic yard per day)
Duration
Time

12. Linear scheduling methods
Interpretation Of LOB Graph
Location
Time buffer
Distance buffer
When we have two or more activities, the production rate will differ from one to another. The horizontal distance between two lines represents the float of the earlier activity, we called it Time Buffer in LOB.
The vertical distance between two lines represent the distance separating the two operations (called the distance buffer)
Activity A
Activity B
Time

13. Linear scheduling methods
General Notes
LOB is done for limited number of activities
LOB is done for Repetitive activities
Working group is called “Team”, “Crew” or “Gang”.
Default working week is of 5 working days per week and of 8 working hours per day.
The rate of construction of an activity is the slope of the production line and need to keep it constant. (i.e. the lines of activities are parallel).
In order to maintain the Rate of Construction to be constant , it is necessary to provide the needed crews whom can achieve the construction rate (line of balance).

14. Linear scheduling methods
Steps required to Build Schedule by using LSM:
Determine the work activities (a few activities only expected involves in LSM/LOB).
Estimates activities production rates.
Develop an activity sequence
Formula ;
Duration needed to construct 1 unit: Man Hours Required
Optimum gang size * hrs/day
No. of gangs needed: Units per week * hrs for 1 week
Optimum gang size* hrs/day * days/week
Rate of Construction: Actual no. of gangs
Calculated no of gangs

15. Case example Housing Construction Project Given:
No. of Houses: 40 units
Desired rate : 4 units/week
8 working hours/day
5 days/week
Buffer: 4 days
Production rate for 1 unit:
Activity
Man hours
Gang Size A
240 3 B
160 6 C 75 5

16. SOLUTION Operation A Duration of A = 240 = 10 days 3*8
No of gangs needed = 4*240 = 8 gangs
3*8*5
Start of unit 1A = Project Start (day 0)
Finish of unit 1A = Project start + Activity duration
= 0+10 = 10 days (day 10)
Start of unit 40A = Start of unit 1+(n-1)* duration
no of gangs
= * 10/8
= (day 48.75)
Finish of unit 40A = days
= (day 58.75)

17. SOLUTION
Operation B
Please refer to attached LOB Full notes for the answer

18. SOLUTION
Operation C
Please refer to attached LOB Full notes for the answer

19. SOLUTION Plotting the LOB lines

20. Matrix Schedule
Matrix schedule are used on construction projects where there is a large amount of repetitiveness in the building design, such as construction of offices, apartment buildings or hotels.
The key principles is to keep the crews working on the same activity and consistently moving through the building in a pattern following immediately behind the preceding activity.

21. Matrix Schedule
Matrix schedule is fairly simple, usually used for small, less complex projects.
Does not have a clear way of showing interaction between different task.
Matrix Schedule work by first breaking down the building into manageable sections.

22. Matrix Schedule
Section sizes are determined by the durations for the amount of work that needs to be completed.
e.g. if the matrix schedule is for pouring slabs, it would be most efficient to break the floor plan up into sections no larger than the maximum square footage of concrete that can be poured in one day

23. Matrix Schedule CASE EXAMPLE
The project that utilize the matrix scheduling technique is the construction of 10-storey Office Building in Washington D.C. The matrix schedule was created for the cast in place concrete activity for level P3 through the ground level and for 2nd level to the roof level. Those two areas are shown on the same schedule but are not related matrix schedules due to the difference in area size and design.

24. Floor plan for 2nd floor to the roof floor
Floor plan for 2nd floor to the roof floor. The levels were broken up in to eight sections and labeled A through H. Each section is roughly 7,000sq feet. Next the sequence was developed for each sections.

25. Matrix Schedule CASE EXAMPLE
Activity sequence for 2nd level to roof:
Using matrix schedule, duration for every activity were calculated by using daily output data from Resources Schedule Means (R.S. Means). Using formula D=Q/PR (Duration=Quantity/Production Rate). Fairly detail resource management is necessary to ensure an effective and smooth running of the construction. Too many resource at one time can cause congestion and problems with movement of crews through the building.

26. Matrix Schedule CASE EXAMPLE
Color legend for Matrix Schedule
Another interactive way to display the matrix schedule is using color legend. Color code use to represent each activities involves for the construction.

28. End of Chapter 3
Thank You