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Construction Quality

Measuring the Quality and Efficiency of Construction Projects

Peter Furst | September 1, 2023

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A construction worker climbing a ladder and installing plywood to the exterior of a building

Due to various complex factors, the management of site-related issues are somewhat difficult. This relates to the factors beyond control, such as supply chain, weather, industry, and economic issues, and the quantification of these various and diverse factors. Productivity is the efficiency of production of goods or services expressed by some means. The primary measurement of productivity is the number of units produced per worker hours expended.

Work efficiency studies, usually surveying the workforce, generally has a demotivating effect, as employees may perceive they are being spied on. Special precautions must be taken to avoid this perception, such as educational and/or informational sessions. The studies may be labeled as improving efficiency by identifying barriers and pinch points, improving flow and access, and requesting suggestions and input from them.

There are many ways to determine productivity. One practical proven technique proposed by James Adrian and LeRoy Boyer in 1976 is the method productivity delay model (MPDM), which may be used to measure the effectiveness of construction workers and crews. This method may be modified to better address unique or specific site conditions. If for some reason observation is not conducive, the use of intervalometers may provide some time and motion information, though with less detailed information; there is a more advanced means of production efficiency assessment through simulation methods.

Measuring Performance

General Work Performance

There is managing by walking around. Project field supervisors tend to walk around the project for any number of reasons, checking or evaluating progress, giving directions, making changes, and solving problems, to name a few. The superintendent may use this time to arrive at an educated assessment of work progress in general. Using the scheduled allotted time for any trade, they may decide that they are an acceptable percentage completed and, if not, decide if some form of intervention may be required.

The degree of work completed to that point in time needs to be compatible with the supervisor's general comfort with their ability to make a somewhat accurate judgment of how far along that crew has progressed toward completing their work. Another way to make such a general judgment may hinge upon the assumption of how many craft persons were deemed to be required on a daily basis to complete the work in the time allocated in the project schedule. So, if the number of workers is less than the assumed number, it may indicate to supervision that a particular trade or crew needs to be monitored more closely in order to ensure that the work will be competed as planned.

Field Work Performance

An astute supervisor can use the walk-around time to collect more detailed valuable information on the effectiveness of their foremen or subcontractors and the productivity of the workforce. One way to accomplish this is through fieldwork rating. Fieldwork rating is based on a simple method of observing individual workers to determine if they are in one of the three following states.

  • Putting work in place (productive)
  • Engaged in some supporting activity (semiproductive)
  • Waiting around not working (unproductive)

This data is then entered into a form that can later be evaluated to arrive at some useful information regarding the progress of the work in general and the effectiveness of the workforce, as well as project productivity in general.

Table 1. Sample Completed Productivity Assessment Form

Productivity Form

Trade: Carpentry





Total 5 3 2
Percent 50 percent 30 percent 20 percent

The form shows total observations made of workers' effectiveness while engaged in their tasks based on the defined categories. So, the productive observations, which is 5 divided by the total of 10 observations, indicates that that particular worker was productive 50 percent of the time, semiproductive 30 percent of the time, and unproductive 20 percent of the time. If the observer makes comments as to why the worker was possibly semiproductive or unproductive, it may indicate areas where possible improvements may be made. This may require longer observation time to garner such information.

Work Sampling

Another way to accomplish worker productivity assessment is through work sampling, which is based on statistical sampling theory. Work sampling estimates the percentage of time a worker is productive relative to the total time that person is involved in the operation. To accomplish this, the following approach can be adopted.

  • Classify the work categories in the three areas enumerated above or define alternate classifications that may be more applicable or useful.
  • Create a data collection form similar to the one above or one that is more in line with project needs.
  • Randomly observe workers utilizing the same means and methods.
  • Record the observation data, and then calculate the resulting information.

The simplest method is to observe a small number of workers for a short period of time to determine their productivity. For work sampling to be effective, the observer must make a large number (about 4,000) of observations. That number must be determined from statistical sampling theory—a function of the defined sampling error factor 5 percent and a confidence level of 95 percent. The number of required observations may be calculated based on other limits or confidence factors.

To some extent, work sampling measures productivity indirectly, as a result, the criteria selected for evaluation needs to be representative of meaningful scopes of work with useful representative measurement. As an example, residential framing involves nailing. But, to count the number of hammer blows and how long it takes to drive a nail will not provide a meaningful measure of framing productivity. Likewise, evaluating the productivity of placing concrete slabs on grade or on metal decks by evaluating individual workers is not informative. Rather, look at the crew as a whole as a function of the time it took to put in place a certain amount of square footage of concrete.

This can be evaluated as a function of shorter time intervals as in say 5- or 10-minute segments to assess the individual crew member to better understand the proper flow of the work to identify down or idle time. Concrete is placed by a crew involving workers spreading the material, setting screeds, adding rough grading, leveling the material with a bull-float, finishing it, and then curing. This might identify opportunities for multitasking to reduce idle time of some crew members and improve the efficient use of labor.

Field Survey Shortcoming

Some of the sampling methods discussed above highlight efficiencies but do not pinpoint causal factors involved with inefficiency. As a result, the process does not identify means or methods of how to go about "fixing" this serious shortcoming. So, the existing process may have to be modified to capture the necessary information as well as a potentially more intensive observation function.

Another method is to devise a questionnaire to be provided to the foremen and/or craft persons, soliciting input as to what should be changed to reduce or eliminate idle or inefficiently utilized time. A more direct means would involve getting the crew to participate in a fact-finding discussion addressing inefficiency causations. Another method may be to have a focus group participating in a fact-finding session to identify ways to find and reduce inherent performance inefficiency.

A Productivity Evaluation Model (PEM)

The productivity evaluation model (PEM) is a derivation of the MPDM as a method to combine both time study and productivity measurement. It is an effective way to measure productivity and any idle time or delays that impact efficiency, as well as to provide more information than other work sampling or evaluation techniques. Utilizing a spreadsheet program can automate the data collection process with macros aiding the computations.

The observer initials the form indicating the date the production unit was observed as well as the cycle time (i.e., seconds, minutes, or hours) then commences observing and recording the production unit's cycle times. Depending on the production unit, there may be a built-in idle time that will necessitate adjustment to improve the efficiency of the operation. The observations may identify delays that will provide information for further improving the productivity of the operational means and methods.

Determination of the Production Unit

This involves a determination of what work is going to be evaluated. It requires identifying a repetitive part of the work being performed that is easily observable and timed. This could represent any work performed on-site involving material, labor, equipment, or some combination thereof. An example could be moving truckloads of excavated dirt, hanging drywall boards, placing structural steel or concrete block, etc.

Determination of the Production Cycle and Time

The production cycle is the total time that it takes to complete one production unit that the observer times and records. This can be measured in seconds, minutes, or hours depending on the production unit. Each operation has a key component, such as the excavator in excavation, carpenters in framing, a crane in steel frame erection, etc. If any of these stops working, then production stops, and it is easily observable for tracking and timing. If there are no delays during that production cycle, then the time of that operation is noted as the cycle time.

There may be small variations in the various "no delay" cycle times. The average of these production cycles may be treated as the base cycle time for that production unit. If there are any delays, they are noted in the specific delay column. The next step involves identifying the cause of the delays to see which ones need to be modified for production efficiency improvement.

Some production units have a combination of activities, such as the excavation of foundations that require dirt removal, which requires that an excavator dig and trucks move the dirt. This means that there are two key components: a production cycle may start with an empty truck in a position ready to be loaded by the excavator and ends with the next empty truck in position for loading. It is possible that the excavator may be idle waiting for an empty truck to show up or an empty truck is waiting for the one being filled to leave. This idle time indicates a potential built-in delay in the operation, which should be discovered very early in the evaluation process and corrected, as it may be a significant inefficiency impacting the productivity of the operation.

Identification of the Types of Delay

The sample form below has seven identified sources for delays: the site work environment, material, labor, equipment, general contractor field staff, subcontractor supervision, or some other issue. These categories must be tailored to reflect areas that are more in line with the specific project or situational factors. If two different types of delay occur in the same production unit, the observer should determine what the percent of each delay time is applicable to each one and record those times in the appropriate column.

A form for production efficiency data
Data Collection and Processing

After the observer establishes the production cycle and the time it takes to complete it, the number of completed production units is recorded. The observer must also determine whether a delay took place during a given cycle and its nature based on the categories of delays on the form. The length of the production cycles cannot be too short or too long as proper tracking then may become an issue. Time-lapse photography may also be utilized to capture short processing cycles.

After some observation of a production unit, the idle and typical delay times should be resolved, and continuous observation should not be required. So, the person making the observation should be able to establish the number of cycles per hour the typical operation should take. That value can then be used to spot-check the efficiency of the operation on a random basis to make sure production is progressing as expected. If that is not the case, then observations should be reestablished to detect what else requires modification or change.

For production units that are ongoing for some time, the operations are observed to get a sense of the degree of the quality of the productivity—then continuous observation is not required. But, to ensure that the operation is progressing as expected, the base cycle time may be used to spot-check the operation to get a sense of the operational efficiency of the productivity. If various delays are common in the production unit, then an hourly rate may be a more useful measurement standard.

From a review of the collected observation data, a typical group of observed cycles containing the typical number of delays within the span of an hour should provide a number of cycles per hour. This can then be established as a standard production rate per hour. Then the person on the project staff overseeing this work may use the hourly standard production cycles rate as a check to ensure that the level of production is in line with the established standard.

Analysis with Simulation Models

This is a method that imitates a construction operation, and simulation is a powerful tool that can be effectively utilized in various aspects of construction management. One of these is in the area of the estimation and evaluation of operational productivity, which involves utilizing different soft computing techniques to forecast the productivity of construction operations. This methodology may be applicable in some special cases or situations.


There are a variety of factors that impact operational productivity or the amount of work that is put in place per worker hour. There generally are a variety of ways to address this, such as internal and external factors, people and systems factors, or project and organizational factors, to name a few. Another way to address this may involve labor, supervision, management, and leadership factors, along with design, owner, consultant, or possibly financial, execution plan, coordination, or supply chain factors.

Other possible factors are somewhat more difficult to assess. They may involve disruptions, complexity, quantity of changes made, relationships, dependability of partner promises, complexity of the supply chain, etc. Productivity may also be impacted by the "quality" of the production plan, the onboarding of a capable workforce, the task design, the matching of the task demand to the assigned worker's capability, the availability of the appropriate tools and equipment, and the list goes on!

Fundamentally, the method selected to evaluate the effectiveness of the project's productivity must be practical, be appropriate for the project, effectively meet the contractor's needs, and, most importantly, add value to the project operations.

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