This document discusses the impact of scheduling decisions on construction project productivity. Specifically, it examines working overtime and increasing workforce size (crowding).
Working overtime can reduce project duration but also decreases worker productivity. The more days and hours worked per week beyond a standard 40-hour week, the lower the productivity. Working overtime for an extended period can decrease productivity by up to 30%.
Increasing workforce size through crowding workers can also lower productivity. The larger the expanded workforce is relative to the normal size, the greater the expected reduction in productivity, according to a presented formula. Doubling the workforce may lower productivity by 15%, for example. Crew stacking multiple groups in a confined area further exacerbates losses.
The
The objective of performing work sampling study on myself as the subject monitoring my daily activities for a period of 20 days is to analyse the proportions of time spent in the various activities performed by me during the period of study and how can use the time more efficiently to achieve my goals. I have selected sports, studying and attending classes as 3 major category of activities I perform during the day and other category for the remaining activities. I chose sports as my first category because playing gives me an opportunity to learn different sport that I am interested in keeping my body active and my mind fresh. Its keeps the adrenaline flowing into my body for the rest of the day or next day. 2nd category i.e. studying helps me fulfil one of my primary objective of maintaining a good GPA in school and the 3rd category attending classes gives me an opportunity to gain knowledge in various topics of industrial engineering to which I am enrolled in UTA.
Performance Rating of workers on Assembly Line or Employees in Industry, Systems of Rating: Pace Rating, Westinghouse Rating, Objective Rating, Synthetic Rating
Work measurement: Job design determines the content of a job, and method analysis determines how a job is to be performed. Work measurement is concerned with determining the length of time it should take to complete the job. Job times are vital inputs for workplace planning, estimating labor costs, scheduling, budgeting and designing incentive systems.
A capsul to explaine a part of industrial engineering,time study, one of the powerful tools that used to adapt the Rhythm inside the value stream, to create an eye on the process and to improve & control the process cost.
Survey of Finance and Engineering Economics Presented byMoha.docxmattinsonjanel
Survey of Finance and Engineering Economics
Presented by
Mohammed Ali Alsendi
Nadia Mohammed Daabis
Instructor
Professor Wajeeh Elali
Time Value of Money
Time value of money refers to the concept that a dollar today is worth more than a dollar tomorrow.
Case study
NATASHA, 30 years old and has Bachelor of science degree in computer science.
Working as Tier 2 field service representative for a telephony corporation located in Seattle, Washington.
She has $75,000 that recently inherited from her aunt, and invested this money in 10 years treasury bond.
Terms of Common Inputs
Current Salary $38,000/-
She don’t expect to lose any income during the Certification or while she earning her MBA.
In both cases, she expect her salary differential will also grow at a rate of 3% per year, for as long as she keep working.
Keep using the interest rate as discount rate for the remainder of the problem
CAMPARISME SUMMARYOption 1 "Network Design"Option 2 "MBA"PositionTier 3Managerial PositionCost$5,000 $25,000 / YearPeriod1 year3 years Salery Increasment$10,000 $20,000 Payment DueEnd of 1 yearBegin of each yearRiskAbove 80% on an exam at end of courseEvening program which will take 3 years to complete
Summary
Timeline
Option 1
Option 2
t0
t1
t2
t3
$38,000
$39,140
$50,614.20
$52,132.62
$38,000 x 3%
($39,140+$10,000) x 3%
$50,614.20 x 3%
($5,000)
($25,000)
($25,000)
($25,000)
$39,140
$40,314.20
$41,523.626
$38,000 x 3%
$39,140x 3%
$39,140 x 3%
t4
$53,696.59
$63,369.33
($41,523.626+$20,000) x 3%
$52,132.62x 3%
Timeline Graph
Current Sutation 38000 39140 40314.200000000004 41523.626000000004 42769.334780000005 44052.414823400009 45373.987268102013 46735.206886145075 Certificate 38000 39140 50614.200000000004 52132.626000000004 53696.604780000009 55307.50292340001 56966.728011102015 58675.729851435077 MBA 38000 39140 40314.200000000004 62123.625999999997 63987.334779999997 65906.954823399996 67884.163468101993 69920.688372145058
Yearly Income
Treasury Bond
Amount $75,000
Period 10 years
Rate 3.52% (1st June, 2009)*
A marketable, fixed-interest government debt security with a maturity of more than 10 years. Treasury bond make interest payment annualy and the income that holders receive is only taxed the federal level.
t0
t1
t2
t10
($75,000)
Treasury Bond
$9027.19
$9027.19
$9027.19
…..
PVA(ordinary) = PMT 1 – (1+k)-n
K
$75,000 = x 1 – (1+0.0352)-10
0.0352
PMT = $9027.190
[ ]
[ ]
C ...
The objective of performing work sampling study on myself as the subject monitoring my daily activities for a period of 20 days is to analyse the proportions of time spent in the various activities performed by me during the period of study and how can use the time more efficiently to achieve my goals. I have selected sports, studying and attending classes as 3 major category of activities I perform during the day and other category for the remaining activities. I chose sports as my first category because playing gives me an opportunity to learn different sport that I am interested in keeping my body active and my mind fresh. Its keeps the adrenaline flowing into my body for the rest of the day or next day. 2nd category i.e. studying helps me fulfil one of my primary objective of maintaining a good GPA in school and the 3rd category attending classes gives me an opportunity to gain knowledge in various topics of industrial engineering to which I am enrolled in UTA.
Performance Rating of workers on Assembly Line or Employees in Industry, Systems of Rating: Pace Rating, Westinghouse Rating, Objective Rating, Synthetic Rating
Work measurement: Job design determines the content of a job, and method analysis determines how a job is to be performed. Work measurement is concerned with determining the length of time it should take to complete the job. Job times are vital inputs for workplace planning, estimating labor costs, scheduling, budgeting and designing incentive systems.
A capsul to explaine a part of industrial engineering,time study, one of the powerful tools that used to adapt the Rhythm inside the value stream, to create an eye on the process and to improve & control the process cost.
Survey of Finance and Engineering Economics Presented byMoha.docxmattinsonjanel
Survey of Finance and Engineering Economics
Presented by
Mohammed Ali Alsendi
Nadia Mohammed Daabis
Instructor
Professor Wajeeh Elali
Time Value of Money
Time value of money refers to the concept that a dollar today is worth more than a dollar tomorrow.
Case study
NATASHA, 30 years old and has Bachelor of science degree in computer science.
Working as Tier 2 field service representative for a telephony corporation located in Seattle, Washington.
She has $75,000 that recently inherited from her aunt, and invested this money in 10 years treasury bond.
Terms of Common Inputs
Current Salary $38,000/-
She don’t expect to lose any income during the Certification or while she earning her MBA.
In both cases, she expect her salary differential will also grow at a rate of 3% per year, for as long as she keep working.
Keep using the interest rate as discount rate for the remainder of the problem
CAMPARISME SUMMARYOption 1 "Network Design"Option 2 "MBA"PositionTier 3Managerial PositionCost$5,000 $25,000 / YearPeriod1 year3 years Salery Increasment$10,000 $20,000 Payment DueEnd of 1 yearBegin of each yearRiskAbove 80% on an exam at end of courseEvening program which will take 3 years to complete
Summary
Timeline
Option 1
Option 2
t0
t1
t2
t3
$38,000
$39,140
$50,614.20
$52,132.62
$38,000 x 3%
($39,140+$10,000) x 3%
$50,614.20 x 3%
($5,000)
($25,000)
($25,000)
($25,000)
$39,140
$40,314.20
$41,523.626
$38,000 x 3%
$39,140x 3%
$39,140 x 3%
t4
$53,696.59
$63,369.33
($41,523.626+$20,000) x 3%
$52,132.62x 3%
Timeline Graph
Current Sutation 38000 39140 40314.200000000004 41523.626000000004 42769.334780000005 44052.414823400009 45373.987268102013 46735.206886145075 Certificate 38000 39140 50614.200000000004 52132.626000000004 53696.604780000009 55307.50292340001 56966.728011102015 58675.729851435077 MBA 38000 39140 40314.200000000004 62123.625999999997 63987.334779999997 65906.954823399996 67884.163468101993 69920.688372145058
Yearly Income
Treasury Bond
Amount $75,000
Period 10 years
Rate 3.52% (1st June, 2009)*
A marketable, fixed-interest government debt security with a maturity of more than 10 years. Treasury bond make interest payment annualy and the income that holders receive is only taxed the federal level.
t0
t1
t2
t10
($75,000)
Treasury Bond
$9027.19
$9027.19
$9027.19
…..
PVA(ordinary) = PMT 1 – (1+k)-n
K
$75,000 = x 1 – (1+0.0352)-10
0.0352
PMT = $9027.190
[ ]
[ ]
C ...
1. Which of the following is INCORRECT regarding the process capab.docxjackiewalcutt
1. Which of the following is INCORRECT regarding the process capability index Cpk
Productivity can be improved by
Increasing inputs while holding outputs steady
Decreasing outputs while holding inputs steady
Increasing inputs and outputs in the same proportion
Increasing outputs while holding inputs steady
2. Productivity can be improved by
Increasing inputs while holding outputs steady
Decreasing outputs while holding inputs steady
Increasing inputs and outputs in the same proportion
Increasing outputs while holding inputs steady
3. Which of the following statements is INCORRECT regarding critical paths?
The path that takes the longest time to complete in a project is the critical path.
Activities on the critical path must have zero slack time.
Some non-critical activities may have zero slack time.
For any project, the (expected) project completion time is equal to the (expected) time duration of the project’s critical path.
4. Suppose a project team has arrived at the following time estimates for an activity: a = 4 days, m = 6 days, and b = 8 days. What is the variance involved in this activity?
0.111
0.250
0.444
0.694
5. Suppose you are asked to determine the Lower Control Limit for a p-chart for quality control purposes. Samples are taken from the production line. The fraction defective is 0.008 and the standard deviation is 0.002 based on the samples. Set z = 3. Which of the following is the LCL of the p-chart?
0.001
0.002
0.006
0.013
6. The least squares method is to find out the intercept and the slope of a regression line that minimizes the sum of the squared differences between
observed values of the independent variable and predicted values of the independent variable
observed values of the independent variable and predicted values of the dependent variable
observed values of the dependent variable and predicted values of the dependent variable
None of the three is correct.
7. Which of the following statements is INCORRECT regarding corporate missions?
They reflect a company's purpose.
They indicate what a company intends to contribute to society.
They are formulated after strategies are known.
They define a company's reason for existence.
8. Given forecast errors of -2, 5, 10, and -3, what is the mean absolute deviation (MAD)?
2.5
3
4
5
9. Which of the following best describes the process focus strategy?
Appropriate for high-volume, low-variety production
Equipment or processes are arranged based on the progressive steps by which a product is made.
Also known as flow shop
Appropriate for low-volume, high-variety production
10. According to the definition of design quality,
Quality is the degree of excellence at an acceptable price
Quality depends on how well the product fits consumer preferences
Even though quality cannot be defined, you know what it is
Quality is the degree to which a specific product conforms to design specifications
11. Which of the f ...
IMPROVING OSH & PRODUCTIVITY OF RMG INDUSTRIES BY IMPLEMENTING LEAN TOOLS AN...Karina Islam
The garment industry has played a pioneering role in the development of industrial sector of Bangladesh. The RMG sector is expected to grow despite the global financial crisis of 2009.As China is finding it challenging to make textile and foot wear items at cheap price, due to rising labor costs, many foreign investors, are coming to Bangladesh to take advantage of the low labor cost. Though Bangladesh produces garment with lowest cost but poor productivity. To survive and prosper in today's economic times, companies can no longer manage using financial measures alone, they have to track non-financial measures also such as customer satisfaction, brand preference, speed of response, employee satisfaction etc.Productivity can improve by applying lean tools like- 5s, JIT, Muda, Root Cause analysis, KPIs, VSM. For improving the ultimate productivity OHS of RMG sector of Bangladesh should be improved. In Ready Made Garments (RMG) sector of Bangladesh, the employees represent an organization's biggest and its most valuable asset. The company's productivity, and ultimately, its profitability depend on making sure all of its workers perform up to their full potential. This paper summarizes that how KPIs analysis improve productivity and OHS of RMG sectors. Appropriate indicators are first selected for KPI scoring then simulate the scores with the help of Adaptive Network-based Fuzzy Inference System (ANFIS) and finally illustrated how KPIs impacts on overall productivity.
Question 1 Copper is a good conductor.True False Questio.docxIRESH3
Question 1
Copper is a good conductor.
True
False
Question 2
Doping is a process of adding impurity atoms to an intrinsic crystal to alter its electrical conductivity.
True
False
Question 3
You can quickly check the condition of a diode with an ohmmeter on a high resistance range.
True
False
Question 4
The letter Q is an abbreviation for quiescent, which represents the AC signal is operating between cut-off and saturation points of the transistor.
True
False
Question 5
The half-wave rectifier has a diode in parallel with a load resistor.
True
False
Question 6
In an NPN transistor, the emitter and collector are both n-type materials.
True
False
Question 7
The dc beta is also known as the current gain because a small base current controls a much larger collector current.
True
False
Question 8
The load line is a visual summary of all the possible transistor operating points.
True
False
Question 9
With the switch in the position as shown in Figure 1 below, the LED is on.
Figure 1
True
False
Question 10
A transistor can be tested using an ohmmeter to check back and front resistances of emitter-base, collector-base, and collector-emitter.
True
False
Question 11
Hard saturation refers to any design that makes the saturation current gain approximately:
1
10
100
1000
Question 12
While testing a transistor with an ohmmeter, a high reverse/forward resistance ratio for the emitter-base and base-collector junctions indicates
this transistor is good.
this transistor is open and should be replaced.
this transistor is shorted and should be replaced.
this transistor is a small-signal amplifier.
Question 13
A major advantage of an optocoupler is the:
electrical isolation between input and output circuits.
electrical connection between input and output circuits.
higher gain.
low cost of manufacturing the device.
Question 14
With normal circuit operation, Vout in Figure 2 is ________.
Figure 2
Approximately 0V
115 Vac
20 V
10 V DC
Question 15
If the 115 V ac is removed from the circuit shown in Figure 2, what would be measured at Vout?
Figure 2
approximately 0 V
115 V
20 V
10 V
Question 16
What type transistor connection is shown in Figure 3 below?
Figure 3
common emitter
common collector
common base
emitter follower
Question 17
What is the device that increases a transistor's power rating by reducing the internal heat faster?
heater wire
chassis
grommet
heat sink
Question 18
Another name for diode offset voltage is:
barrier potential
ripple voltage
surge voltage
filtered voltage
Question 19
The second approximation of a silicon diode is basically the:
the diode appears as a switch in series with a barrier potential of 0.7 V
the diode appears as a switch in parallel with a barrier potential of 0.7 V
the diode appears as a barrier potential of 0.4 V
the diode appears as a short circuit
Question 20
What is the most popular ...
This paper introduces benchmarking as a concept that not only helps provide a framework and a repeatable approach to developing structurally sound schedules (based upon accepted Critical Path/CPM techniques), but equally importantly, bring realism to the schedule.
Standard Costing: Management Accounting Cambridge A Level Paper 3 last 2 questions: Payback period: Discounted Payback period: Accounting Rate of Return (ARR): Net Present Value (NPV): Internal Rate of Return (IRR) : Sensitivity Analysis: Cambridge A2 Standard Costing Past Papers
Standard Costing
Candidates should understand the application of a system of standard costing to an organisation.
Candidates should be able to:
• calculate the following variances:
– direct material price and usage
– direct labour rate and efficiency
– fixed overhead expenditure, capacity, efficiency and volume
– sales price and volume
• reconcile standard cost to actual cost
• reconcile standard profit to actual profit
• explain the causes of the variances and their relationship to each other
• discuss how standard costing can be used as aid to improve the performance of a business
• discuss the advantages and disadvantages of a standard costing system.
Cycle time is the actual time it takes an operator to complete an operation, from start to finish. It includes the time spent on both productive and non-productive activities.
SMV (Standard Minute Value) is the theoretical time it takes an operator to complete an operation at their normal pace, without any delays or interruptions. It is calculated by taking the cycle time and multiplying it by the operator's performance rating.
To learn more about Textile- https://textilemerchant.blogspot.com
A case study on productivity improvement of wearing insert and cutting ringIJECSJournal
The objective of this paper is to present case study on a wearing insert and cutting ring for the efficient improvements in productivity with the help of various work Study Methods. In this study productivity is improved through identifying the process that involves the time required for the process as the main reason to achieve the objectives of increasing the productivity. Time and motion study is one of the necessary factors to set a standard target. The study is aimed at identifying the unwanted work processes which in turn increases the time required, efforts as well as the cost of the product. Thus the changes were made in the areas which require improving using work study methods.
Space Age Furniture Company The Space Age Furniture Company manufa.docxwhitneyleman54422
Space Age Furniture Company The Space Age Furniture Company manufactures tables and cabinets to hold microwave ovens and portable televisions. These products are made in various sizes and with various features, but all follow basically the same production and assembly operations. However, two of these products—the Saturn microwave stand and the Gemini TV stand—have a part (no. 3079) that requires machining on a special lathe used only for making that part. At present the machine is run by Ed Szewczak, a machinist who also operates other machines in Space Age’s shop. Once set up and started, the lathe can run nearly unattended. However, the machinist must be present (even if not actually attending the machine) any time one of the machines, including the lathe, is in operation. At present, Ed works a regular 40-hour week. However, due to the workload for producing part 3079, it has been necessary to schedule frequent overtime for him in order to finish the necessary parts on time.
Coral Snodgrass, operations manager for Space Age, has just heard from Ed’s foremen that Ed is becoming unhappy about so much overtime. As Coral knows, Ed has been with the company a long time and is an excellent, reliable employee. Skilled machinists with Ed’s experience and employment record are extremely difficult to find. Coral wonders what can be done to alleviate this problem.
Recently, Space Age began using an MRP system that has helped reduce inventories greatly and improve on-time deliveries. In fact, Space Age carries no finished-goods inventory. Instead, everything in the master schedule is being produced for customer orders, so all products are shipped almost immediately. Previously Space Age had estimated that it cost $1.25 per week to store each Gemini and $1.50 per week to store each Saturn that wasn’t shipped immediately. The master schedule for producing these two items for the next six weeks is shown below.
Master Schedule
Week 1 2 3 4 5 6 Gemini 600 400 700 500 400 600 Saturn 300 400 400 600 300 300
von70154_09_c09_257-302.indd 294 2/22/13 3:31 PM
CHAPTER 9Discussion Questions
The part in question, 3079, is used in two different subassemblies: no. 435, which is used in the Gemini TV stand, and no. 257, which is used in the Saturn microwave stand. One of part 3079 is used in each subassembly, and one of each subassembly is used in each of the final products.
Part 3079 may be produced in any quantity since the lathe that makes it is not used for anything else. However, both of the subassemblies are produced using the same equipment. To minimize change over time, Space Age has decided that these subassemblies should be made in minimum quantities of 1,000 at a time, although there is no problem with capacity on the equipment that makes them. In fact, an order for 1,000 of subassembly 435 is due to be received in week 1, as is an order for 1,000 of subassembly 257. Lead time for both these subassemblies is one week, and no inventory is expect.
1. Hashemite University
The Impact of Scheduling
Decisions on Productivity
Construction Planning and Scheduling
Shaha Maiteh, Tamara Ta'amneh
2014
2. Abstract
Factors affecting construction in were disclosed in previous studies carried out by the
authors, which confirmed that the construction industry has experienced
productivity problems in many countries. The objective of this paper is to identify
factors that should be focused upon, when productivity improvement is to be initiated.
To do so, 34 project managers working in the construction industry completed a
structured questionnaire survey and the factors were ranked according to their
perception of their levels of influence and their potential for improvement based
on their overall experience in managing projects in the industry. To supplement
the questionnaire data, in depth interviews were conducted with some project
managers.
We will focus in this report on two important factors which are Working
overtime, increasing Workforce (Crowding).
This study is intended to create the foundation for further study of construction
productivity measurement and improvement, which aims to lead to overall
productivity improvement.
4. Table ofContent
Abstract ………………………………………….…………
Table of Content …………………….……….……..………
Introduction ………………………………………….……..
Working Overtime...…………………………………..……
Increasing the Workforce (CROWDING).……………….
Summary and Conclusion…………………..………………
References……………………………………………………
5. Introduction
As a contractor undertakes a construction project, he or she begins to make decisions
that are intended to contribute to the efficient delivery of the final constructed facility
to the owner. These decisions ideally take into account the impact that given strategies
will have on the project costs, schedule, and quality. This requires the decision maker
to be cognizant of the impact that his or her directives will have on the overall project.
While very little is published on the relationship among project costs, schedules, and
quality, it should be clear that there are often very close associations between them.
Many decisions made regarding the schedule are those intended to reduce the
duration of selected activities. While the rationale for these decisions may appear
logical at first glance, they may have adverse impacts on other aspects of the project,
especially in terms of productivity.
6. Working Overtime
A common response to the need to accomplish more work in a smaller time frame is
to have workers work overtime. The workers are already on site and they simply need
to be informed of the need to work additional hours each day or to work on the week-
ends. What will the impact be on productivity if workers are asked to work overtime?
Perhaps, if they are asked to work overtime for two or three days, the adverse impact
may hardly be noticeable or may be nonexistent.
However, it is generally accepted that working overtime for an extended period of
time adversely impacts productivity. While little has been published on this topic,
some have used the following formula to predict the productivity impact of working
overtime for an extended period:
Eff (%) = 100% — 5 [(days — 5) + (hours — 8)] %
Where:
Elf = Worker efficiency based on 100% for a regular 40-hour week.
days = Number of days worked per week.
hours = Number of hours worked per day.
While generic in its format, the equation does give some insight into the impact that
overtime can have on worker productivity/other considerations have to be taken into
account before placing heavy reliance on the equation.
For example, since setting up an operation consumes a considerable amount of time,
it would seem logical that the overtime should first be applied to the existing
workdays rather than adding another workday to the schedule.
If workers carpool, the impact of having; some workers working overtime may
have an adverse impact on morale.
If workers commute considerable distances to get to the work site, there will
be additional considerations.
By examining the above formula, one can get a quick glimpse of the impact of
overtime on labor productivity. Based on the formula, the associated efficiencies have
been determined for given overtime schedules (see Table.1). Note that the normal 40-
hour workweek has been defined as the benchmark for 100% efficiency.
7. For example, if 12 hours are worked each day for seven days per week (84 hours per
week), the efficiency drops to 70%. For this scenario, it can be said the productivity
of this 84-hour workweek is equivalent to working 58.8 hours at 100% efficiency. In
addition to the drop in productivity, the decision maker must also evaluate the
impact of this scheduling decision on the costs of wages. Obviously, in an 84-hour
workweek, more than half of the time will be worked at premium wages.
Table.1
IMPACT OF SCHEDULED OVERTIME ON LABOR PRODUCTIVITY
Hours/Day Days/Week Hours/Week
Efficiency
(based on 40 hr.)
Effective
Fir./Week
8 5 40 100% 40
9 5 45 95 42.75
10 5 50 90 45
11 5 55 85 46.75
12 5 60 80 48
8 6 48 95 45.6
9 6 54 90 48.6
10 6 60 85 51
11 6 66 80 52.8
12 6 72 75 54
8 7 56 90 50.4
9 7 63 85 53.55
10 7 70 80 56
11 7 77 75 57.75
12 7 84 70 58.8
Example:
A contractor employs a workforce of 20 workers on a construction site for a private
owner. The workers are paid an average wage of $12.00 per hour. Because of
slippage in the schedule, it now appears that the project will not be completed on
time, and there is a liquidated damages provision of $1,000 per day for every day
that the project is extended beyond the contractual deadline. The contractor is now
contemplating working 12 hours per day for five days each week. If the contractor
expects to make up or shorten the project duration by ten days, is this a viable
option?
8. Considerations:
By using the formula on overtime or by referring to the information in Table.1, it is
easy to determine that the 60 hours worked each week per worker will be at a level
of productivity achieved with 48 hours of work (using a 40-hour workweek as a
baseline). Thus, if the 20 workers are assigned to this same work schedule, the
project duration will be reduced by eight hours or one day for each week of such
work. Therefore, it will take ten weeks to reduce the schedule by ten days.
What Is the Cost of Overtime?
Since the average wage of the workers is $12.00 per hour and since any work hours
above 40 hours are paid at an overtime rate of $18.00 (assuming time and a half), it
can be determined that the premium pay, the overtime portion of the base wage, is
$6.00 per hour for 20 hours each week, or $120.00 per worker. The cost of the
overtime pay for the entire workforce is $2,400 per week. From this, the contractor
might very well conclude that each day that the duration is shortened will cost
$2,400 (the cost of the overtime portion of the wage).
What Is the Cost of Lost Productivity?
It must be realized that working 60 hours each week nets only 48 hours of regular per-
formance. The contractor's estimate assumed one hour of production for every hour
worked. This means that there are 12 hours of regular work hours lost each
week per worker, which equates to $144 per week per worker, or $2,880 for the
20 workers.
Another way of examining the production and overtime cost issue is to simply look at
the additional labor costs incurred each week. Since the contractor will be paying
straight time wages for 40 hours and time and a half for 20 hours, this is essentially
the same (in terms of costs) as incurring a straight time labor wage cost for 70 hours.
Since only 48 hours of production are realized, it can be said that the contractor
loses 22 hours of wages each week that are attributable to the overtime cost and the
lost productivity.
The 22 hours at straight time would cost $264 ($12.00 X 22) per worker each week.
This equates to a weekly cost of $5,280 for the crew of 20 workers. Note that this is
the same as the sum of the overtime cost of $2,400 and the lost production of
$2,880. Thus, at a cost of $5,280, the contractor can avoid a liquidated damages
charge of $1000.
What Are the Savings?
When compared to the liquidated damages of $1,000 per day, it appears that the added
cost of overtime and the lost production far exceeds the cost of damages. If the
numbers were a little closer, as they might be if there was a five-person crew only,
some additional considerations should be addressed.
9. For example, every day that the project duration is shortened will also reduce the
number of days that the equipment and staff will be required on the project. The
superintendent might be paid $1,000 per week, resulting in an additional savings of
$200 per day. Depending on the type of equipment being used on the site, there will
be additional savings, especially if the equipment is rented or could be utilized on
another site.
There are certainly other considerations that are difficult to quantify.
For example, the company's reputation might be bolstered if it can deliver the project
on time, and this might be beneficial for being awarded future contracts.
INCREASING THE WORKFORCE (CROWDING)
Working overtime may be desirable in situations where a quick response is needed or
where training costs for certain skills are high. However, a contractor may also
decide to add extra workers to the workforce.
In some cases, this added workforce may be asked to work on a second shift. On new
construction projects, this may not be explored due to the requirements for
additional lighting and the lack of supervisory or managerial personnel for the
second shift. If additional workers are employed on the regular shift, it stands to
reason that some complications can arise, especially if the workforce is increased by
a significant amount.
When additional workers are hired on a construction site, management must consider
the impact that these workers will have on the existing resources.
For example, is there an adequate supply of hand tools and various pieces of
equipment? It would be foolish to double the crew size for concrete placement
without also increasing the supply of concrete vibrators and screeds. If the resources
can be provided, the next consideration is the impact that the additional workers on
the site might have on labor productivity.
10. This possible reduction in productivity can be attributed to the crowding that can
occur in a work area, shown in the following formula:
Eff (%) = 115% — 15 (size of expanded workforce/size of normal work force) %
Where:
Eff = Worker efficiency based on 100% for a normal workforce.
From this formula, the productivity can be computed when workers are asked to work
under conditions of crowding (see Table .2).
Table.2
THE IMPACT OF CROWDING
ON LABOR PRODUCTIVITY
Relative Size of Workforce Relative Productivity
Normal %100
10% above Normal 98.5%
2 Times Normal 85%
3 Times Normal 70%
4 Times Normal 55%
5 Times Normal 40%
6 Times Normal 25%
Based on the computed impacts of crowding on productivity, it can be seen that a
10% increase in the crew size will have only a minor impact on worker productivity.
Often, the evaluation should not be based on the total workforce but rather on the
actual work being done.
For example, if a project has 100 workers and 10 additional pipefitters are hired, the
impact on productivity, as assessed with the use of the crowding formula, will be
small. However, the impact might be quite adverse if the pipefitters are assigned to
a work area where 2 pipefitters were already working. This would result in 12
workers in an area previously occupied by 2 workers.
11. The impact will be compounded if crew stacking occurs. This will occur when
concurrent activities are scheduled for the same location as a result of a change or
where some type of project compression is required. Crew stacking is not
specifically addressed by the above formula because it is focused primarily on an
increase in crew size.
If other crews are also forced to work in the same area, productivity will be com-
promised further. This loss in productivity will arise from crews competing for
access to the same doorways and passageways, and they may also compete for the
use of the same tools or power sources. In some cases, their productivity will be
compromised simply through the inability to store materials or tools conveniently
and to move freely. Such crew stacking conditions might require crew sizes to
actually be reduced.
Example:
A specialty contractor employs a workforce of 20 carpenters on a construction site
who are paid an average wage of $12.00 per hour. The carpentry work is running
behind schedule and the contractor is being faced with a liquidated damages
provision of $1,000 per day for every day that the carpentry work is extended
beyond the contractual deadline. The contractor would like to explore the possibility
of increasing the workforce to 30 carpenters. If the contractor expects to make up or
shorten the project duration by five days, is this a viable option?
Considerations:
By using the formula on crowding, it is computed that the 50% increase in the number
of carpenters will result in a level of productivity that is 92.5% that to be expected in
a 40-hour workweek. Normally, the 20 workers would each accomplish 40 hours of
work each week for a total of 800 productive hours per week for the entire crew.
With the additional workers, the productivity level per worker will be reduced to 37
hours each week per worker, or a total of 1,110 productive hours per week for the
crew. From this, it is determined that the 30 workers will reduce the schedule by
0.38 week ((1110-800)/800), or 1.94 days for each week that is worked. If the
additional ten carpenters are employed for three weeks, the carpentry work will be
reduced by more than five days.
What is the Cost of Lost Productivity?
Working with the additional carpenters, the workforce will have 37 productive hours
each week. Thus, the contractor will lose three productive hours for each carpenter
each week, which equates to 90 hours lost each week for the entire crew, or 270
hours over a three-week period. This will cost the contractor $3,240 in lost
production over the three-week period.
12. What Are the Savings?
By working a crew of 30 workers, the schedule will be shortened by five days. When
considering the liquidated damages of $1,000 per day, it is apparent that $5,000 will
be saved in liquidated damages by employing the additional ten workers. Of course,
there are other considerations. Are the additional carpenters as skilled as the 20
already on the project or are they relatively unskilled and unfamiliar with the
company?
This will dictate to a large extent whether the formula to compute productivity is even
realistic. The assumption in the formula is that the additional workers are of the
same skill level as the existing crew. If the added workers are less skilled than the
existing carpenters, the productivity will probably be well below 92.5%.
The specific job site conditions will also impact the productivity of the workers.
Judgment will need to be exercised when considering the addition of workers to a
crew.
For example, suppose an office building is being constructed. Production losses might
be minimal if an additional crew is brought in to perform drywall installation. The
drywall crews would probably be assigned to install drywall in different rooms.
Thus, there would probably be a minimal adverse impact on productivity. If the
additional workers are assigned to perform work in the same location as the existing
workers, the impact on productivity could be considerable.
For example, suppose two plumbers are installing plumbing fixtures in a bathroom. If
two additional plumbers are assigned to assist with the installation of these plumbing
fixtures, the impact on productivity could be considerable. There may be instances
in which the cramped conditions could result in even less work being performed
with the additional workers.
The unique conditions at the job site and the specific tasks being performed will
dictate the reliability of the formula for computing productivity with the addition of
workers.
13. Conclusion
In this report we have found that there have been construction productivity
problems, and disclosed the most significant factors affecting construction
However, various suggestions were raised in order to improve productivity by
alleviating the effect of adverse factors. Improvement of an organization's
productivity should now be focused on, since this will not only make an
organization more profitable, but also increase its chance of survival in the industry,
especially as there is very high competition due to the economic crisis.
If improvement in many organizations' productivity can be facilitated, overall
construction productivity will also be improved. Therefore, using this report as a
foundation, future studies will concentrate on productivity improvement.
14. Reverences
Critical Factors Influencing Construction Productivity ,The
Journal of KMITNB., Vol. 14, No. 3, Jul. - Sep. 200
Partnering in construction: a critical review of issues, problems
and dilemmas, MIKE BRESNEN1 and NICK MARSHALL2, Warwick
Business School, University of Warwick, Coventry CV4 7AL, UK, 2Complex
Product Systems Innovation Centre, Centre for Research in Innovation
Management, University of Brighton, Falmer, Brighton BN1 9PH, UK,Received
16 December 1998; accepted 18 March 1999 Construction Management and
Economics (2000) 18, 229±237
Construction Planning and Scheduling, 3rd edition, Jimmie W. Hinze,
July 2007, Publisher: Prentice Hall.