Presentation on theme: "CE 403 Construction Methodology Construction Productivity."— Presentation transcript:
CE 403 Construction Methodology Construction Productivity
Construction Methodology 2 Measures of Construction Performance Construction performance involves all aspects of the construction process. It is a broad inclusive term that includes four elements: – Safety – Timeliness – Quality – Productivity
5/30/ WORK INJURY AND ILLNESS RATES Incidence rates expressed as number of cases per year or days per 100 full-time employees or 200,000 employee hours per year Incidence Rate = (# of cases or days per year x 200,000)/Total employee hours per year Can be computed for each category of cases or days.
Construction Methodology 4 Construction Performance: Timeliness Interpreted both as on schedule and everything is on hand when needed
Construction Methodology 5 Construction Performance: Quality Means that the facility and all its elements meet the specification requirements Owners Perspective: Test performances Craft (Field) Perspective: Rework
Construction Methodology 6 CORRECTION: Field Productivity Actual productivity determines whether or not the project will be completed within the cost budget and time schedule Labor Productivity = Production Output/Workhours Factor Productivity = Production Output/Total Cost Productivity Factor = BCWP/ACWP Direct Work Rates (i.e. tool time or wrench time)
Construction Methodology 7 Factors Affecting Labor Productivity
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9 Factors that have an adverse effect on productivity Overtime and/or fatigue Errors and omissions in plans and specifications Multitude of change orders Design complexity Design completeness Stacking of trades Dilution of supervision Reassignment of manpower from task to task Material location – Above ground level – Above floor level Adverse temperature or weather Inadequate lighting
Construction Methodology 10 CORRECTION: Field Productivity Actual productivity determines whether or not the project will be completed within the cost budget and time schedule Labor Productivity = Production Output/Workhours Factor Productivity = Production Output/Total Cost Productivity Factor = BCWP/ACWP Direct Work Rates (i.e. tool time or wrench time)
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What causes change orders…at least in Highway Work. Reason CodeFrequencyAvg. CO Amt. ($) Avg. Percent Change in Original Contract Amt. Asphalt Lot Pay Adjustment 188$7, % Fuel & Asphalt Adjustment 218$82, % Contract Omission243$57, % Utility Issue60$35, % Contract Item Overrun 227$104, % Geotechnical Issue71$90, % Owner Induced Enhancement 186$88, % Environmental Issue20$19, % F-Value P-Value0.000 KYSPR Statistical Analysis of Change Order Data 610 Projects 246 New Construction 364 Maintenance Projects Projects Completed between 2005 and 2008
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Construction Methodology 18 Factors that have an adverse effect on productivity Overtime and/or fatigue Errors and omissions in plans and specifications Multitude of change orders Design complexity Design completeness Stacking of trades Dilution of supervision Reassignment of manpower from task to task Material location – Above ground level – Above floor level Adverse temperature or weather Inadequate lighting
Construction Methodology 19 Factors that have an adverse effect on productivity Regulations of various types High absenteeism High turnover Material shortages High accident rates Jurisdictional disputes Work rules and restrictive work practices Availability of skilled labor Attitude of the workforce Crew size and composition Timeliness of decisions
Construction Methodology 20 Construction Inflation Empire State Building Costs: $40,498,900 (1931 Dollars) $559,321,201 (2006 Dollars CPI Adjusted) Freedom Tower Proposed Costs: $1.6 to 2.1 Billion (2006 Dollars)
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Construction Methodology 22 Why Train? What are the Benefits? Data from winners and finalists of the Workforce Development Excellence Award (Houston Business Roundtable) OSHA Recordable Injuries down 67%, First Aids down 90% Productivity up 10 to 24% Rework down 50 to 70% Turnover down 32 to 43% Unexcused Absences down 59% Worker Morale and Company Loyalty is up
Construction Methodology 23 Company A: Absenteeism and Turnover Data The study found that workers receiving training had a lower turnover and absenteeism rates than workers without training. Workers without Training Company Certified Workers Worker Receiving Training Turnover Rate6.51%3.39%0.63% Absenteeism Rate7.28%0.27%2.51%
Construction Methodology 24 Company B: Productivity Data Company B Productivity Performance Factor vs. Percentage of Certified Plus TM Craft Workers R 2 =0.39 F value =6.478 P value = A declining performance factor indicates productivity improvement TM Certified Plus is trademarked by NCCER
Construction Methodology 25 Factors that have an adverse effect on productivity Regulations of various types High absenteeism High turnover Material shortages High accident rates Jurisdictional disputes Work rules and restrictive work practices Availability of skilled labor Attitude of the workforce Crew size and composition Timeliness of decisions
Construction Methodology 26 Factors that have an adverse effect on productivity Impractical QA/QC tolerances Uncontrolled breaks Time of day and day of week Inadequate temporary facilities: parking, change rooms, restrooms, etc.
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Construction Methodology 28 Preconstruction concepts which promote productivity Improve site access Early procurement of materials Identification of materials in known locations Pre-planned procedures Pre-assembled components Proper sequence of work Adequate construction equipment Obtain necessary small tools Secure licenses, permits and inspections Level manpower
Construction Methodology 29 Engineering concepts which promote productivity Timely information Simplified details Practical tolerances Avoid interferences Minimize changes Allow prefabrication
Construction Methodology 30 Four Methods for Determining Cost and Time Allotments 1. Horseback, or Ballpark, Estimates 2. Estimates by Qualified Experts 3. Historical or Statistical Estimates 4. Estimating by Computed, or Engineered, Standards
Construction Methodology 31 Method 1: Horseback, or Ballpark, Estimates Draw on knowledge of similar projects done in the past Apply adjustments for such factors as inflation, relative costs between geographical areas Considered approximate E.g. X dollars per lineal foot of floor area
Construction Methodology 32 Method 2: Estimates by Qualified Experts Relies on personal knowledge and skill of an expert Relies on the experience of an individual and their knowledge of the conditions under which the task will be done Common practice is to involve field personnel – Superintendents, foreman, lead-man
Construction Methodology 33 Method 3: Historical or Statistical Estimates Relies on records of previous projects to determine cost and time required for appropriate: – Individuals – Crews – Machines – Other conditions For those without in-house information, books and other publications give unit performance rates for more common construction operations – Eg. Means, Richardson Process Plant Estimating Standards, Dodge Unit Cost Books
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Construction Methodology 36 Method 4: Estimating by Computed, or Engineered, Standards Computed standards utilized measured values of time required for trained individuals to carry out basic movements Pro: Can be very accurate Con: Very time consuming for the planner
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Construction Methodology 39 Current Methods for Assessing Work-Face Productivity Work-face activities often get little attention Most construction analyses involve examining project cost and schedule performance. A projects success can be made or ruined at the workface. Two categories of workforce assessment methods – Informal – Formal
Construction Methodology 40 Current Methods for Assessing Work-Face Productivity Informal: – All construction managers will tell you they can judge how well a work-face task is going by merely watching for a short period of time. – However, they may not be asking themselves such questions as: Are materials and tools available and suitable? Is the work procedure and its sequencing the most efficient? Have tasks been assigned among members of a crew that best uses available skills and keep all hands busy?
Construction Methodology 41 Current Methods for Assessing Work-Face Productivity Formal: – Most common assessment methods: slippages in schedule and cost overruns. – Problems: Can be based on after-the-fact information May be inaccurate (not recorded accurately) – Errors in coding – Falsified to hide slippage
Construction Methodology 42 Current Methods for Assessing Work-Face Productivity Other formal methods: – Time studies using photographic or video methods – Questionnaires and Interviews Eg. Foreman Delay Surveys – Work Sampling
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Construction Methodology 44 Work Sampling Consists of observing and classifying a small percentage of a projects labor activity Involves making and analyzing the results of field observations to determine what individual workers are doing at specific instants in time. Most of the data is recorded in the following Categories: – Productive Work Direct Work Tools Materials Information – Non-Productive Personal Travel Waiting
Construction Methodology 45 Work Sampling Direct Work (25-65%): – Activities directly involved in the actual process of putting together or adding to a unit being constructed – Includes necessary disassembly of a unit that must be modified and movements essential to the process where the work is being done – E.g. painting a wall, placing bricks, nailing boards to a wall, hauling material from an excavation, threading pipe, mixing mortar, cutting boards before nailing.
Construction Methodology 46 Work Sampling Support Work: – Preparatory Work or Instructions Receiving instructions Receiving drawings Using telephones or radios for work related reasons Discussing material, tool, or equipment needs – Tools and Equipment Locating a tool in a gangbox and transporting it to the task areas Obtaining and transporting slides, shackles or similar tools equipment Putting on and adjusting personal protection equipment (PPE) – Material Handling Supporting crafts transporting bulk materials (Operators and Teamsters are Direct Work)
Construction Methodology 47 Work Sampling Delays: – Doing something that is in no way necessary to complete the job. – Waiting – Travel (empty handed (toolbelts), walking to and from work areas) – Personal (rest periods outside break times, adjusting personal clothing, rest room or water breaks outside break time).
Construction Methodology 55 Work Sampling The rating should be taken at the first instant of observation. Dont anticipate a persons action Counts should not begin until at least ½ hour after start time and ½ hour before quitting or lunch time. Must be an equal likelihood of observing every worker. Sample shall contain no less than 384 observations Basic characteristics of the work situation must remain the same.
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Construction Methodology 59 Direct Work Support Delay Want to maximize Total Construction Time 0% 25% 50% 100% Work Sampling Break down into subcategories for class project.
Case Study Idaho Falls Nuclear Decommissioning Project. Treating nuclear, sodium- bearing waste from a liquid to a solid state using a steam reforming process Primary Trades: Piping, Concrete, and Instrumentation Initial Budget: $84M Final Budget: $176M Construction Methodology 60
Construction Methodology 69 Work Sampling Example: Edmonton Project
Construction Methodology 70 Work Sampling Limitations Work Sampling provides a measure of worker efficiency Worker efficiency can only be considered an indirect measure of productivity. Reviewed with great suspicion by craftsmen and foremen
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75 Percent Direct Work by Crafts* Pipefitters/Welders28% Boilermakers27% Electrical Workers28% Laborers41% Carpenters42% Insulators26% Operating Engineers39% Ironworkers31% Millwrights32% * Productivity in Power Plant Construction, Marjatta Strandell, 1976 AACE Transactions, pp
Construction Methodology 76 Source: Oglesby, C., Parker, H., and Howell, P. (1989) Productivity Improvement in Construction. McGraw-Hill, New York, New York.