MANAGEMENT:CIVIL II_ MCIV 2/0

MODULE FIVE(5): LINE OF BALANCE(LOB) PLANNING JB NARTEY

LINE OF BALANCE(LOB)• In construction there are some projects in which a predominant feature is that of

repetition.

• The following are typical examples: • Housing contract• VIP Toilets• Piling contract• Capping piles• A block of flats• A hotel with a series of identical rooms• etc. • For such work it is extravagant, as well as difficult, to draw and maintain critical path

networks illustrating the detail of the construction process for each of the units involved.

•

LOB REQUIREMENTS

• A required delivery programme/Rate of delivery for completed units.

• Contract Period• The dependency and relationship of work

activities . • Labour input per section of the unit

EXAMPLELOB TUTORIALS

Your company has been appointment for construction of 40 similar RDP houses in East London rural areas. Details of the contract are as follows:

You are required to deliver the houses at a rate of 4 units/ week. Total project period not to exceed 15 weeks. You plan to work a 5 day week. You plan to work 8hrs per day.

The table below illustrate the information after you have done the calculations.

Operation Man-hours/unit

Gang/Team Size

Foundations 240 3

Brickwork/plastering 160 6

Roof 75 5

You are required to do the following:

(a) Draw the LOB chart graph. Allow a 4-day buffer period between activities.

(b) Use the information provided to determine the number of units expected to be started and completed after 50 days of construction.

(c) Does the project meet the specified duration for completion? Provide explanation to support your answer.

(d) How many planned days does it take to complete the project?

FOUNDATIONSSolution;

a) Foundations;

Duration = Man-hours/unit/ [Gang Size/unit x hrs/day] = 240/3x8 = 10 days

No. of Gangs needed(theoretical) = Desired prod rate x man-hours/unit/[gang size/unit x hrs/dayxdays/week] =4 x240/3x8x5 = 8 gangs

No. of Gangs needed(Actual) = 8 gangs

Start of foundations on unit 1= day 0

Finish of foundations on unit 1= day 10

Start of foundations on unit 40 = 0 +(40-1)x10/8 = day 48.75

Finish of foundations on unit 40= day 58.75

Rate of Construction = Desired prod rate x Actual No.of gangs/Theoretical No.of gangs= 4x8/8 = 4 units per week.

Checks: Rate of Construction = 40 units/ (58.75/5) = 3.75 units per week approx 4 units per week.

Keep the rate of construction as uniform/balanced as possible between the activities and close to 4 units per week

58.75 days( 11.75 weeks)

0 10

Foundunit1

10 days

48.45 58.75

Found unit 40

10 days

BRICKWORK/PLASTERINGBrick work/Plastering;

Duration =Man-hours/unit/ [Gang Size/unit x hrs/day] = 160/6x8 = 3.33 days

No. of Gangs needed(theoretical) =

Desired prod rate x man-hours/unit/[gang size/unit x hrs/dayxdays/week] = 4 x160/6x8x5 = 2.67 gangs

No. of Gangs needed(Actual) = 3 gangs

Start of brickwork/plastering on unit 40= 58.75 + 4 = day 62.75 ( 4 days buffer)

Finish of brickwork/plastering on unit 40 = 62.75+3.33 = day 66.08

Start of brickwork/plastering on unit 1= 62.75-(40-1)x 3.33/3 = day 19.46

Finish of brickwork/plastering on unit 1= 19.46+3.33 = day 22.79

Rate of Construction = Desired prod rate x Actual No.of gangs/Theoretical No.of gangs =4x3/2.67 = 4.49 units per week> 4 units/week

46.62 days( 9.32 weeks)

Checks; Rate of Construction = 40 units/9.32 weeks =4.2 units per week>4 units/week,ok

Keep the rate of construction as uniform/balanced as possible between the activities and close to 4 units per week

19.46 22.79

Brickwork/plasteringunit1

3.33 days

58.75+4/62.75 66.08

Brickwork/plastering unit 40

3.33 days

ROOFINGRoofing;

Duration = Man-hours/unit/ [Gang Size/unit x hrs/day] =75/5x8 = 1.87 days

No. of Gangs needed(theoretical) = Desired prod rate x man-hours/unit/[gang size/unit x hrs/dayxdays/week] =4 x75/5x8x5 = 1.5 gangs

No. of Gangs needed(Actual) = 2 gangs

Start of roofing on unit 40= 66.08+4 = day 70.06 ( 4 days buffer)

Finish of brickwork/plastering on unit 40 = 70.06+1.87 = day 71.93

Start of roofing on unit 1= 70.06-(40-1)x 1.87/2 = day 33.60

Finish of roofing on unit 1= 33.60+1.87 = day 35.47

Rate of Construction = Desired prod rate x Actual No.of gangs/Theoretical No.of gangs =4x2/1.5 = 5.33 units per week> 4 units/week

Checks: Rate of Construction = 40 units/7.67 weeks = 5.2 units per week>4 units per week,ok

38.33 days( 7.67 weeks)

Keep the rate of construction as uniform/balanced as possible between the activities and close to 4 units per week

33.60 35.47

Roofingunit1

1.87 days

66.08+4/70.06 71.93

Roofing unit 40

1.87 days

LOB Diagram/chart4 days buffer 4 days buffer

10 20 30 40 50 60 70 80403938373635343332

Units 31302928272625242322212019181716151413121110

987 Time of Completion6543210 10 20 30 40 50 60 70 80

Duration(days)Time of measuring progress

FoundationsBrickwork/PlasteringRoofing

CONCLUSIONS

• Refer to LOB Chart/Graph;• After 50 days of construction;• Foundations are expected to be completed on 33 units• Brickwork/plastering is expected to be completed on 25

units• Roofing is expected to be completed on 18 units.• • Refer to LOB Chart/Graph;• Expected period of completion ; 71.93 days = 14.3

weeks< 15 weeks•