cee 498 project

7/27/2019 CEE 498 Project

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CEE498 CONSTRUCTION PROJECT MANAGEMENT

PROF AWAD HANNA

PRODUCTION CONSULTANTS: TJK DESIGNBUILD STUDY REPORT

DOUGLAS FRASER

13 DECEMBER 2007


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Abstract

Our client, TJK DesignBuild construction, hired us to study their jobsite at 22 EastDayton, located in downtown Madison. Their project is a five-story, 48,000 square footcondominium complex of with two underground parking levels of 1600 square feet.Construction began on 17 September, 2007 with a tentative finish date of 1 July 2008.The job supervisor in charge of job site is Douglas McIntosh.

Productivity Consultants conducted their work sample study in mid October 2007. Theresults from our analysis show that the concrete crew was involved in direct work 25% of the time, indirect work 30% of the time, and inefficient work 45%. The Labor Utilizationfactor was approximately 33%. These results were slightly below the averagesexpected, but correlated with the production delays seen later in our study.

The Five Minute sampling study was postponed until mid November to test our hypothesis that the work rates would improve, since this was very early in theconstruction phase. The results of our Five Minute study show the work crew had anefficiency rating of approximately 70%. Therefore, we concluded the data from thesetwo studies supported the general performance factor model in the first quarter of construction phase.

For our macroscopic analysis, we chose to focus on the location of the latrine, work crewnumber, and scaffolding process and composition. Based on our process analysis, the

jobsite should split their latrine location, with one located central to the work area whilekeeping one latrine adjacent to the operations center. The work crew typically had 7men on site during the work sampling study. We recommend cutting this number to 5based on the amount of observed idle time. The scaffolding process could be improved

both in material and safety. Our advice is to rent (or buy) two man-lifts to accommodateworkers, or invest in a more modular plank system with rails.

Our micro-analysis focused on one three man work crew establishing a rebar frame.The current process had two rebar emplacers and one material transporter. We suggestcutting the transport worker and replacing him with a forklift, or pre-staging the rebar closer to the work area

In sum, we concluded this is an average job site with some good habits and room for improvement. The Productivity Consultants recommend that this job site also investmore time supervising the work crew, keep the same work crew to maintain teamcohesion, and invest in a digital productivity system such as MS Project in order to trackprogress. If the company follows our advice, their efficiency and productivity levels willrise; and consequently, their profit margins.


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Introduction

In the twentieth century, mass production and quality control concepts spawnedscientific management: the study of management practices to improve labor productivity.Today, Six Sigma and Lean construction are descendants of scientific management.The core of all of these models is efficiency. Like all industries, productivity is the criticalvariable for the efficiency of a construction company and therefore, its profitability. Considering approximately 90% of construction companies have less than 20 workers,profit margins may decide whether a small business flourishes or fails.

Proving and pricing l ost productivity claims can be a difficult task. However, if certainbasic fundamentals are present, accepted methods of analysis do exist.

- Synergen Consulting, Labor Productivity Analysis

There are many difficulties of measuring productivity. The basic fundamentals of efficient versus inefficient work are constant throughout industry, but uniqueness of the

jobsites, environmental variables, as well as multiple human factors all play a varyingrole in over productivity in construction. However, in order to improve processes, we firstmust analyze quantifiable data. Despite the myriad of variables, we can still performrelatively simple tests to quantify the general productivity of labor.

Objectives and Scope of Study

The overall objective of this work study is to isolate one process of theconstruction system and apply productivity analysis and improvement techniques toidentify problems in the process and system. Our recommendations will then be based

on the results of our study.

The study will be limited to three testing methods: a work sampling study, 5minute rating, macro and micro process analysis. We will discuss them in depth later inthe report, but they can be summarized as follows:

1. A Work Sampling Study is a technique to determine the nature of observableactivity as an indicator of overall performance. Specifically, we used worksampling to identify productivity shortfalls in a concrete foundation crew. In order to limit the bias of our data, we observed the crew on a random interval and froman inconspicuous location.

2. The 5-minute rating technique was conducted as an additional analysis of theconcrete work crews performance.

3. Micro and macro method improvement study. In the micro analysis, a crewbalance chart and process flow diagram will be used to identify inefficiency inconstruction methods.

Initial Site VisitBefore we began our research, we visited a few TJK construction sites in

downtown Madison. During our initial site survey, we took photographs of the site,


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talked with the workers and foreman to determine their work schedule and activities, andgathered necessary information to prepare our productivity analysis. A site diagram andvarious photographs of the job site are included in Appendix 1. The project is a fivestory, 48,000 square foot condominium complex with 2 underground parking levels.Construction began on 17 September 2007 with a completion deadline of 1 July 2008.

The general impression of the work area was congested. However, this is in downtownMadison and workspace is premium. We had to consider the cramped workspace for allour tests and recommendations.

Work Sampling StudyThe first productivity study we conducted was the work sampling study, or

productivity rating. Work sampling is a measurement technique for the quantitativeanalysis of the activities of men, equipment, or any other observable condition of theoperation (Thomas, 1980). A work sampling consists of a sufficient number of observations taken on random intervals over a period of time. During each sampling,the state of the job site, the weather, and the activities of each crew member are noted.See Appendix 1 for our conditions during each sample.

The three classifications of work we used were direct work, indirect work, andineffective work. Direct work, or effective work, is defined as the actual process of constructing the observed unit, such as mixing concrete, emplacing rebar, or erecting aprefabricated wall. The ideal construction model would have productivity factors of 100%, as all tasks would contribute directly to the product being made. In reality, thiscan never be the case: some necessary tasks have little or no direct benefit to theproduct. Due to this fact, we need two more work categories: indirect work andineffective work.

Indirect work, as the name implies, is any task not directly related to the creation

of the finished product, but is essential to the process. In our study, this categoryincludes: receiving or giving instructions, building scaffolding, inspections, or themovement of tools and materials within the work area.

Ineffective work can best be described as performing activities not conducive tothe completion of the product. Standing around idly, walking around empty handed, andsmoking breaks can all be categorized as ineffective work. Since this is a productivityimprovement study, our analysis revolves around identifying and improving ineffectivework.

Activities observed in the Work Sample study At the time of this study, the site was previously excavated and part of the outer

foundation wall was erected. The work study analysis focused on the construction crewemplacing concrete walls and foundational pads. This activity was selected because itwas labor intensive and critical to the completion of the building. Because of therestricted site size, only one crew was typically working at any given time during our study.

The study period was conducted over three weeks. We conducted our worksampling observations separately from our 5 minute rating and macro and micro


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analyses. The general weather during the work study was cloudy with temperaturesranging from 40 to 60 degrees. On two days the ground was saturated from rain theprevious night.

The work sampling study was conducted by both of the members of our group.We used a digital camera to ensure we captured the work at the specific moment for this

study.

Categories of work

It is important to define all criteria and categories for our work crew. In concretework, building or stripping forms, placing concrete, or finishing the surface all will beconsidered direct (effective) work. Activities critical to creating a product, yet do notdirectly lead to the finished product are considered essential contributory work. Carryingmaterials, erecting scaffolds, and clean-up will be categorized as essential contributorywork.

Ineffective work is any activity which does not positively contribute to theprocess. However, it is sometimes difficult to classify differences between essentialcontributory work and ineffective work. For example the idleness can be sometimes dueto waiting of materials or tools rather than because they stop working intentionally. Thisaspect was difficult to distinguish from our vantage point beyond the work site.

Activity Classification and Categories of Work

After much deliberation, we decided to break down work activities into thefollowing categories.

Direct work:

1. Pouring concrete2. Emplacing rebar 3. Emplacing concrete forms4. Mixing concrete

Essential contributory work:

5. Obtain or transport tools and materials6. Give/receive instructions7. Directing machine operator (concrete mixer, fork lift, backhoe)8. Raise scaffolding9. Move scaffolding10. Clean up11. Bracing concrete forms

Ineffective work


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1. Traveling empty handed2. Idleness3. Waiting for materials4. Rest breaks5. Obtaining tools outside of immediate work area

6. Weather delay7. No contact

Confidence Limits and Observations According to the statistical definition, survey sampling is random selection of a

sample from a finite population. Provided the sample size is adequate, the risksassociated with random allocation (such as failing to obtain a representative sample in asurvey, or having a serious imbalance in a key characteristic between a treatment groupand a control group) are calculable and hence can be managed down to an acceptablelevel.

To reach a credible confidence level in our data, we had to compute theminimum number of observations needed. We were given a tolerance level of +/- 5%,giving us a 95% confidence level. We used the following equation to determine thenumber of observations:

Where: N = the number of observations requiredP = the decimal equivalent of the percentageexpected in the categoryS = decimal equivalent of the degree of accuracy

K = the number of standard deviations needed for agiven confidence level

Based on the 95% confidence level, S was computed as .05. We determined thenumber of standard deviations at 95% confidence from statistical charts, and inferred Kas 1.96. The P variab le is the expected variability in our observations. If we have noprior knowledge of the outcomes, we assume P as 50%, allowing the maximumvariability. Since we have previous studies, we assumed our P value as .3

Inserting our chosen confidence and tolerance levels, we calculate the number of observations by solving for N.

N =1.96 2 * .3(1-.3) N = 310 observations.05 2

Therefore, the minimum number required is 310 observations.Random Number GenerationIn order to reduce bias in our study, we had to randomize the timing of our worksampling. First we determined the number of people in the crew we would observe.

Although the number fluctuated daily, the average number of workers was 6. We chose

N =K 2 * P(1-P)

S2


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to observe the crew over 3 days to capture a work week. Therefore, we divided the totalobservations by the product of the number of days observed and the number of crewmembers.

310/(3 days*7 man crew) = 15 observations per day15 samples/day(3days) = 45 sample observations

The formula we used to randomize our 310 observations is as follows:

Random number/100*180+start time = observation timeExample: (13/100)(180)+8:00am = 8:23:40am

This gave us a schedule to collect over 310 randomized data samples on the work crew. A list of all the random computed observation times is included in Appendix 2: RandomNumber Generation

Work sampling data collection

Our observer crew arrived at the worksite approximately ten to fifteen minutes beforebeginning work observation. In order to eliminate as many potential sources of bias aspossible, we established the following rules of observation.

1. Each crew member must be observed when a sample is taken, including if the worker or foreman is present.

2. In order to obtain as much data as possible per work sample, a digital photowas taken for each observation. This ensured no activities were omitted inthe final sample analysis, as well as reducing bias related to work that anindividual was doing in the past as well as work he/she would do in the future.

Only the work activity captured in the photo at that specific time wasrecorded.

3. All observations were recorded from the least conspicuous location near thework area. A parking ramp located across the street provided an elevatedpoint of view for our observations as well as a covered and concealedvantage point. The specific locations of our pictures and data sampling islocated in Appendix 3: Work Sampling

Work Study Results

The observation data collection forms are located in Appendix 3: Work samplingobservation sheets. A complete table categorizing and tallying the data is also located in

Appendix 3. Table 1: work breakdown, summarizes the percentage of each work activityand total number of observations observed within each work activity. Three activities,mixing concrete, waiting for tools, and weather delays were not observed during our study. We did not conclude that the above activities did not occur; they were notobserved over our work sample study. Figure 1 shows a graphical summary of theactivity breakdown. The labor utilization factor can be calculated by the using the


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percentage of direct work plus one quarter of the total percentage of indirect work. Thisfactor will give the managers an indication of overall labor efficiency.

Labor utilization Factor = % direct work + .25(% indirect work)

Work Study Results

The results show that only 25% of the time was devoted to direct work in for the concretework crew. The crew was involved in essential contributory work just under 30% of thetime. The remaining 44% of the time was ineffective work. The Labor Utilization Factor of 32.92% indicates to management that labor is positively contributing to productiononly one third of the total time. These percentages seem lower than normal, but notsurprising based on the amount of standing around observed. A byproduct of thisinefficiency was numerous concrete pouring delays further along. When we were set toobserve their concrete pouring according to their schedule, we were informed that the

pouring was delayed. Nearly a week later, the crew poured the first floor of the building.Reflecting upon our data, this delay could have been predicted early on in our study.

It can quickly be inferred that the work crew productivity can be improved. Much of theineffective work can be eliminated with proper supervision and site improvements. Onenotable change would be the number of workers in the crew. The total crew number observed was typically six or seven workers. At least one worker at any givenobservation could be counted on to be idle. If the crew number was cut to five and theother workers given a different task, it can be inferred that overall productivity wouldquickly climb. We focused more on the crew number in our macro analysis study.

Other possible reasons for the low efficiency are poor management techniques. Itshould be noted that the foreman was rarely seen walking around the jobsite. Since thisstudy was conducted within the first weeks of the construction, this work crew may notbe experienced working together as a team. Additionally, since this work focused on thefoundation, environmental factors such as muddy conditions become moresignificant. We must note that two of the observation days were conducted the day after substantial rainfall. However, this may have slowed progress, but it does not excuse idletime.


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Work Sample activity breakdownDirect Work(concrete, formw ork,excavation, etc)obtain/transport tools

Receive/give instructions

Read draw ings / Plan w ork

Rew ork

clean, stage or moveequipment)

brace concrete f orms

mix c oncrete

build or move scaffolding

Travel empty handed

Unexplained idleness

Waiting for tools/materials

Weather/emergency delay

No contact

Figure 1: Work Category Breakdown

Figure 2: Work Sample Activity Breakdown


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Five minute rating technique

This is a deterministic measurement employed as a general assessment of the workcrew effectiveness. The observer takes a series of observations over a five minuteperiod and sums up the observations to determine effectiveness in a given time span.

Procedure:

To prevent bias, our group chose observation points far enough from the job site not tointerfere with the workers. We used a small video camera to capture the entire process.Our group took a total of six Five Minute ratings, observing 6 laborers, and gathering atotal of 405 data samples. The data was taken between 10 November and 21November 2007.

Results and Conclusion:

From our data in Table 2: Five Minute Rating Results, our group determined the crew

was involved in effective work for 295 of the 405 observations, which is an effectivenessof 73%. See Appendix 5 for the observational worksheets. Based on these results, weconcluded the crew is relatively efficient. However, this data goes in direct contentionwith the work sampling study. One likely explanation for this is the timing of each study.We conducted the work sampling study in mid October, while the crew was justbeginning their concrete wall and foundation production. The five minute ratingtechnique was conducted in mid November, after the crew had been working as a teamfor well over a month. As discussed in our CEE498 class, repetitive activities generallybecome more efficient over time (until boredom sets in) this indicates the crew isimproving.

Table 2: Five Minute Rating Results

Work SampleNumber

TotalUnits Effective

1 85 722 55 403 105 804 55 395 105 64

TotalSamples 405 295

Work Crew %Effectiveness 72.8%


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Scaffolding Modularization

The crew has a number of good work practices in place, such as pre-marked rebar andstandardized concrete formworks. However, their scaffolding procedure could beimproved. During two observation periods in November, two workers devotedapproximately 50% of their time to fabricating scaffolding. It should be noted they arenot building a complete scaffolding system, but only the walking plank and supports.The supports are standardized and reusable; the planks can be reused, but need to berecut to the new plank length. Considering the amount of time invested in creating thesescaffolds, finding a quicker, reusable solution should increase efficiency and cut down onmaterials needed. One note on safety: there were no railings or workers roped into asafety system on these scaffolds. Our solutions include safety railings.

There are multiple possibilities of varying costs that would improve this process. Onequick fix would be to invest in mechanized system as suggested in CEE498 called amanlift. The total cost of an average manlift researched on the internet in t his areavaries from ten to thirty thousand dollars. On this worksite, the maximum use of scaffolding observed was two crews. Generally, buying the equipment will pay for itself in gained efficiency and labor costs as well as tax deductions, but we are limiting our scope to this project alone, so renting in this short term case is more feasible. A quickeconomic analysis shows the scaffold cost and alternative options. Refer to table 5 for the results. The full table and assumptions can be found in Appendix 6. According toour model, the approximate total scaffold cost over five levels will top $24 thousand.Buying a manlift would pay for itself within two construction projects. Additionally, thisequipment can incur a large tax deduction for procurement and depreciation. Investing

in steel scaffolds also proves to be economical. However, the Productivity Consultantsrecommend the company invests in manlifts.

Table 5: Scaffold simplified economic analysis

total projected scaffold cost $24,433cost of average manlift $30,000steel scaffold (20') $597total price (33) $19,701

adjustable lengthplank/stage system 10-17' $229total needed (33) $7,557


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C hurch

Dayton Street

Apartment

Apartment

Operation

Center

La trine

House

Mai n S torage

e x c a v a t o r

parkingHous e

Key:OperationTransportationInspectionDelaystorage

Cutting site worker

Rebar Framework

wor kers

PrestagedWood

parking

Hous e

Scale: ~50feet CURRENT SCAFFOLD PROCESS

TRANSPORTVIA FOOT r a

m p

ramp

Figure 6: Macro analysis: current scaffold emplacement process

C hurch

Dayton Street

Apartment

Apartment

Operation

Cen

ter

La trine

House

Mai n S torage

e x c a v a t o r

parkingHous e


Cutting site

worker

Rebar Frameworkwor kers

parking

Hous e

Scale: ~50feet SCAFFOLD: replace with Manlift

r a m

p

ramp

Figure 7: Macro analysis: proposed scaffold emplacement process option #1


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C hurch

Dayton Street

Apartment

Apartment

Operation

Center

La trine

House

Mai n S torage

e x c a v a t o r

parkingHous e


Scaffold sit e

worker

Rebar Framework

wor kers

r a m

p

Rebar cache

parking

Hous e

Scale: ~50feet CURRENT WORK FLOW

TRANSPOR TVIA FOOT

ramp

Figure 9: Micro analysis: current work flow for rebar emplacement

Table 6: Crew Balance Chart: Rebar Emplacement


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C hurch

Dayton Street

Apartment

Apartment

Opera

tion

Center

La trine

House

Mai n S torage

e x c a v a t o r

parkingHous e


Scaffold sit e

worker

Rebar Frameworkwor kers

r a m

p

parking

Hous e

Scale: ~50feet Option 1

TRANSPOR TVIA FOOT

ramp

Rebar cache

PRESTAGEDREBAR

Figure 10: Micro analysis: Proposed Work Flow For Option 1

Table 7: Micro analysis Crew Balance Chart Option 1


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Figure 12: Performance Factor Curve projected points observed duringproductivity studies

Recommendations

Our overall recommendations for this work crew are to sustain the efficiency ratesobserved in November and cut the number of personnel in the crew to five. We alsopropose more supervision of the work crew to encourage production.

The scaffolding process could be improved both in material and safety. Our advice is torent (or buy, in the long term) two man-lifts to accommodate workers, or invest in a moremodular plank system with rails.

We suggest cutting the transport worker and replacing him with a forklift, or pre-stagingthe rebar adjacent to the workers.

The Productivity Consultants recommend keeping the same work crew to maintain teamcohesion, and invest in a digital productivity system such as MS Project in order to trackprogress.

cee 498 project

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