The proper evaluation of worker productivity is one very important measure in the determination of project status. To have a complete picture of the status of any project there must be some sort of measure of the productivity of the work force. Certainly, one would be interested in the physical progress, the amount of money expended, the amount committed, absenteeism and turnover rates, safety incident rate, supervision to worker ratio, craft distribution, worker density, manpower history, etc. to properly evaluate the status of a project. But one key factor in evaluation of status is worker productivity. There must be some consistent measure of the productivity of the workers on a project in order to frame the complete picture of project status.
Generally, productivity evaluation is focused on the construction craft workers. However, no less important is the productivity of the office design and engineering staff. Having said that, this article is focused on the field construction staff and evaluation of productivity in the field.
The first step in determination of productivity is understanding what is meant by the term “productivity”. Productivity is how much work is actually being accomplished for the effort expended. In terms of a formula, my view is represented by (the total number of scheduled or estimated hours earned for the completion of a specific task or group of tasks) divided by (the actual hours expended for that specific task or group of tasks). The application of the result would be to divide the manhour estimate for the project by the productivity factor derived from the formula above to determine the forecast number of hours that is expected to be necessary to complete the scope of work. An example is: if it took a crew of workers 125 hours to accomplish 100 hours of estimated work, that would represent a productivity of 100/125 or 0.80. This number would be used to divide into the total estimated field hours to accomplish the work on the project to arrive at a projected total number of hours for the construction work. The forecast number of manhours would then be Estimate divided by 0.80, or Estimate times 1.25.
Productivity is a relative term, not absolute. While productivity from one project to another can be compared, the most valuable aspect is the productivity for one specific project at various times in the life of that project. Why is productivity not absolute? This is true simply because the basis for establishing productivity is the estimate and no two estimates are one hundred percent consistent and accurate. The closer the base estimates are to being consistent and accurate, the closer the productivity numbers are to being absolute. Whatever the situation, the important point is that productivity must be evaluated and done so in a consistent manner using consistent tools and measures.
Productivity can be evaluated using the sophisticated means of computer-based schedules, estimates, earned value measurements, etc. However, it is often important to have an instantly available measure of productivity on a job site. This is not difficult to achieve. The results will never be absolutely infallible or completely accurate. However, they will be consistent and provide a very sound measure of productivity. It is better to be consistent and approximately correct than inconsistent and totally wrong. Consistency provides more accurate and valid results upon which decisions can be based with reasonable confidence.
Enough background, how is productivity evaluated quickly and in a consistent manner? In a tour of the work area, count the number of workers visible. This number will be the denominator of the formula discussed above. While counting the total workers present, also count the workers engaged in actual work – those performing a true work-related task. For example, if there were only two people encountered in the work site tour, a welder and a welder’s helper, then the denominator would be two. If the welder is striking an arc – actually welding, then he is productive and would be counted. If the helper is watching the welder perform the weld, then he is not doing productive work and thus would not be counted as such. So, given this situation, the productivity would be 0.50. Generally, productivity is not expressed with a unit of measure or even a percentage – just a simple number. In this case of the welder and helper, if when we were doing our tour, the two were standing over the weld looking at it and discussing it, neither would be counted as doing productive work and the resultant productivity would be 0 divided by 2 or zero. Another possibility is the welder is watching the helper clean the weld in preparation for laying another pass on the weld area. There is only one worker engaged in productive work and only one would be counted as such. Again, the productivity would be 0.50. This evaluation performed on a consistent basis at several intervals of time will provided a reasonably valid assessment of the productivity. Forecasts of manpower can then be constructed. Decisions related to manpower, craft distribution, labor cost, schedule duration, etc. can be made with reasonable confidence and certainty.
Overall, productivity is easily evaluated. If a worker is actively engaged in meaningful work, he is productive. If he is not actively engaged in productive work at the moment of evaluation, then he is not productive. The key is be consistent in evaluating techniques and “rules of application” – do not vary from one evaluation time period to the next.
On a personal note, while being driven from the gate to the construction trailers on a large construction site, I quickly counted the workers I thought were actively engaged in productive work and the total number of workers I could see. Our route carried us through several work areas and at a slow speed, allowing for reasonable counting and evaluation. I came up with a productivity of 0.10 for the site. I determined that it would be no better than 0.25 regardless of what alterations or allowances I made in the evaluation. As it turned out, the official calculated value given by the contractors was in the 0.15 to 0.20 range. This quick evaluation gave our team several ideas for improvements and areas of further investigation for potential improvement of construction productivity. It also gave us a solid feel for projected end date and final overall construction cost.
This evaluation can be performed several times in a day or once a week. Remember to be consistent in the evaluation method. You will almost never be absolutely right, neither will you be totally wrong. You will always be at least approximately correct.
Richard S. Troell, P.E., President
Copyright 2011 – all rights reserved