The computation of production efficiency factors depends upon numerous variable which affect worker’s productivity in actual job conditions at the project site. These variables vary from project to project, and over place and time. Some of the typical factors affecting the works production efficiency are given in the following. The values for changes in the productivity rate or human effort  are indicated for conceptual purposes; these should be considered as guidelines and not mathematical rules.

Work complexity

A simple, familiar work, is easier to execute than an unfamiliar, complex one. The extra effort needed for the latter type of work, specially in the initial stages, may range from 10-100% of the normal expected productivity.

Repetition of work

While the first- time execution of an unfamiliar work needs extra effort and results in low output, the skill acquired in the process, when utilized over a period of time to execute similar works, improves productivity rate, especially when crew of workers is the same. This improvement in productivity rate continues till a certain limit is reached.
The limit corresponds to the stage when the crew acquires the necessary skill and becomes throughly conversant with the process, and the work is performed at its peak productivity rate. This impact of repetitive work on the productivity rate varies with time. nature of task and the characteristics of the crew. As thumb rule, the improvement in productivity rate can be taken from 5-15% for each repetition, from its initially assessed rate of about 60-80% of the average output rate till it reaches about 120% of the average rate.

Quality control

Stringent quality control is sensitive projects, like in the construction of the nuclear reactor call for frequent inspections, which involve elaborate documentation and is a time consuming task. They increase the non-productive time of workers and in turn reduces productivity by 10-25%.

Equipment-intensive tasks

The construction tasks which can be performed wholly or partly with equipments include excavating, handling, transporting, filling, compaction, grading, hoisting, fabricating, precasting, erecting, plastering, finishing, paving, trenching, cable-laying, pipe-laying, and so on. Generally, special-purpose equipments are required for preforming these tasks. The equipment-intensive tasks are less susceptible to productivity changes than the labour-intensive ones.

Supervision

A supervisor manages his assigned technical work as well as the workers under him. The accomplishment of tasks economically and on schedule mostly depends upon the competence of the supervisor, which in turn affects the worker’s productivity. An efficient and effective supervisor can get a higher productivity from workers.

Climatic and weather conditions

Generally, under average weather conditions with temperature varying from 40-700F and relative humidity of 60%, the workers continue working at the same productivity level. But extreme weather situations and seasonal changes like extreme hot or cold climate, high humidity, and strong winds and rains affect both productivity as well as the work performance.
Since construction projects are spread over several months or even years, it is necessary to adjust the effect of weather changes month-by-month on worker’s productivity as well as work execution. This adjustment in productivity can best the assessed by experience or it can be derived from available area productivity index.

Labour availability

The labour productivity also depends upon the employment opportunities available in the market. If jobs are plenty and labour is scarce, the labour productivity tends to become less. During a slump in the construction market, labour is easily available while there is a dearth of jobs. In such situations, employers can afford to be selective as hiring and firing of workers become easy. In scarce job situation, the overall productivity improves since the employers can then sort out labour with a light productivity. There is also a tendency among labour to move to high-value, large-sized projects since they offer them longer service, better job opportunities and more stability.

Role of management

The project management has a key role to play in planning and controlling productivity. It is responsible for specifying the weekly target of work to be accomplished by the workers as well as how the works are to be executed and using which resources.
During the execution stage, the management provides the necessary resource support and closely monitors the performance. Each week, it compares the planned target with the work accomplished, evaluates variances, analyzes causes for variances, and takes corrective measures.
It provides feedback to the workers on their past performance, and communicates performance improvement measures. It suitably rewards the workers who have done exceptionally well, and keeps the morale of the work force high. The productivity is bound to suffer if the management fails to fulfill its role and obligations effectively.