Engineeringhome Office Estimating

1. STATISTICAL HISTORICAL

a) overall project breakdown(*pie-chart")

b) home office breakdown

2. ENGINEERING HOURS PER EQUIPMENT ITEM a) approx. 1000 - 1500

3 engineering hours per discipline/item a) pipelines/item/tons/c.y./ft.etc.

4 manhours per drawingidocument a) count by design groups

5 add ons/extra functions a) see typical estimate sheet(sub total c)

Figure 6-15.

HOME OFFICE MAN-

HOUR BREAKDOWN

FOR FULL SCOPE EPC

PROJECT

Description

% Man-hours

Design i Drafting

Full-Scope (SJ

Civil i structural

25.00

1Ü.ÜÜÜ

Vessels

7,50

3.ÜÜÜ

Electrical

15.ÜÜ

6.ÜÜÜ

Plant design (piping)

41.ÜÜ

18.4ÜÜ

Piping engineering

5.25

2.1ÜÜ

Bill of material

5.25

2.1ÜÜ

Model

1.ÜÜ

Ü.4ÜÜ

1ÜÜ.ÜÜ

4Ü.ÜÜÜ

Administration-indirecl drafting

4.ÜÜÜ

Engineering

Instrument (engineering ft drafting

)

3.000

Mechanical (rotating machinery.

3.000

plant utilities, metallurgy, etc.)

Mcchnnical (consultants)

Ü.2ÜÜ

Project management

7.5ÜÜ

Project cnRÍnccrin¡r

6 ono

Project (operating expenses.

Ü.2ÜÜ

services administration)

Process design

3.ÜÜÜ

technology services

Ü.1ÜÜ

Project services

67% Engineering

Estimating & cost control

4.ÜÜÜ

Proposals

Computer control

Computer systems

1.ÜÜÜ

Initial operations-office

Ü.2ÜÜ

Technicnl information

Ü.2ÜÜ

Scheduling

2.ÜÜÜ

Procurement

Purchasing

5.ÜÜÜ

Inspection and Expediting

5.ÜÜÜ

General office

Stenogrnphic

4.5ÜÜ

Accounting

7.ÜÜÜ

services

2.ÜÜÜ

Labor relations

Ü.1ÜÜ

Construction (office)

2.ÜÜÜ

Total 1ÜÜ.ÜÜÜ

PRODUCTIVITY LOSS FOR EXTENDED WORKWEEK

There are occasions when a project is placed on extended overtime to shorten the schedule. In many cases, under normal economic conditions, productivity will be reduced and costs will increase. If this condition was not part of the original estimate, an assessment of the increased cost, as well as the schedule advantage, should be made. The schedule evaluation should recognize increased manhours in the duration calculation. It is also possible that absenteeism will increase, sometimes to an extent that there is no schedule advantage for the increased workweek.

Figure 6-23 presents data compiled from the sources indicated and plots labor efficiency against overtime hours worked, based on 5-, 6-, and 7-day workweeks. This data applies only to long-term extended workweeks. Occasional overtime can be very productive with no loss of efficiency. The exhibit shows a recommended range of productivity loss by project size (small-large).

Application

This figure can be useful in an overall evaluation of the impact of overtime hours on schedule and cost. It can establish an increase in total labor hours required for a loss in efficiency due to an extended workweek. However, judgment should be used on an individual location basis. Some areas, particularly less developed countries (LDCs), work 60-hour weeks which are as productive as 40-hour weeks.

Example:

Assume that a project has a total construction scope of 1 million manhours and is based on a 5-day, 40-hour workweek. If the same workweek were increased by 8 hours to 48 hours, look to the chart for 8 hours of overtime, and using the (NECA) 5-day (large project) curve, read across to an efficiency of 90%. This indicates that 10% more hours will be required to accomplish the same amount of work due to a loss in efficiency. Thus, we estimate that the total manhours will be 1 million x 1.10 = 1,100,000 manhours. Schedule and cost evaluations can now be made for an additional 100,000 manhours, but at an increased level of work. Obviously, there is a schedule advantage. Note: These curves do not include efficiency losses for a second shift, which can be about 20%. However, shift work losses depend on the type of work, company organization and experience. In the Offshore Industry, where shipyards traditionally work on a shift basis, losses can be minimal, or zero.

Figure 6-16. Typical Data Points - Engineering.

The following are typical data points for evaluating estimating levels or monitoring project performance.

This data applies to large U.S. process plants. Adjustments should be made for overseas locations and for small projects.

Engineering NOR. U.S.

• Manhoursper drawing (total drawings) 1701185 1 5011 60

• Manhours per piece of equipment 115011400 100011200

• Manhours per piping isometric 15/20 8/10

• Manhours per P & I diagram 4501570 4001500

• Manhoursper plot plan 2301350 200/300

• Manhours per material requisition 9/12 8110

Figure 6-17. Construction Estimate Basis

ITEM

ESTIMATE BASIS

1. Direct Field Labor

Quantities updated by field take off

Productivity factor for time & location

Unit manhours per work operation

Handing & rework by factor

2. indirect Field Labor

Factor on direct labor manhours

(non-productive & lost time)

3. Field Staff

Organization chart

Time frame schedule

Relocation & local living

Replacement &training

4. Temporary Facilities

Dimensioned layouts

Quantity take off

Unit rates

Maintenance by factor

5. Construction Equipment

Listing by category & number

Time frame schedule

Unit rates (rental vs. purchase)

Maintenance by factor

6. Small Tools & Consumables

Factor on direct labor

Loss allowance

7. Field Office Expenses

Factor on direct labor

Listing for office furniture/equipment

8. Escalation & Contingency

By judgment &formula

Note: Direct material purchase by the field is usually covered by the material

estimate.

CONSTRUCTION OVERHEAD COSTS COST ESTIMATING LOGIC

field labor * pmkjuctiv1ty -

aojusted

Labor hahhour5

résultant x composite

L^ce^ME, direct field labor cost fringe benf fit coït labor bijrden cost

SHaLL

TOOLS cost

ihâuaàncës

cost

direct held labor mahhours

DIRECT FIELD LASO MANHOURS

direct field labor

MflWfOURi direct riELO labor mau rs direct held labor mahhours

DIRECT FIELD LASO MANHOURS

direct field labor

MflWfOURi direct riELO labor mau rs

Figure 6-19. HOME OFFICE EXPENSE BREAKDOWN

Figure 6-19. HOME OFFICE EXPENSE BREAKDOWN

Project Management for Engineering and Construction Figure 6-20.

Productivity Without Pain

Productivity Without Pain

Being able to do little yet reap a lot is every individuals ideal work formula. Though not always possible there are some interesting ways this can be achieved to some level of satisfaction for all.

Get My Free Ebook


Post a comment