458 www.ijergs.org Methodical Approach of Determining Labour Constants Models for Building Construction Processes in Nigeria

Abstract — Construction planners and estimators in Nigeria often guess the standards of building tradesmen. These standards are usually given as constants in the form of time necessary for the manual completion of a defined quantity of work – standard time (St), or in the form of unit output – standard output (Sop) for a specified working period. Since it is difficult to draw reliable construction programmes or make accurate cost estimates without any available baseline standards or constants, this study therefore, systematically developed statistical models for determining labour constants for building construction processes. It was a field survey where detailed work study was carried out on two major work sections (concrete work and blockwork) in six building project purposely selected across the South East, Nigeria. Time study technique and a three-time estimate technique were used to determine the most probable duration time (expected time (t)) to complete each operation that makes up an activity relative to the quantity of work performed. From this, the duration time (tka), of key process was determined and subsequently, the standard time (St) and standard output (Sop) (labour constants) were evolved. Thereafter, these were fitted into regression models and the resultant showed that labour constant could be statistically determined. The models were further tested for adequacy, and it was found that all the generated models for various building operation