This study evaluates the cost-effectiveness of using mechanical plant equipment as an alternative to predominantly manual labour in public building construction across South-East Nigeria. A mixed-methods approach was adopted: quantitative cost and time records were collected from a purposive sample of public building projects and contracting firms in the region, while qualitative data were obtained through semi-structured interviews with project managers, site engineers and labour representatives. Data analysis combined cost-benefit techniques (including cost-effectiveness ratios and payback comparisons), basic inferential statistics, and thematic analysis of interview material. Findings indicate that although initial capital outlays for mechanical plants are higher than for purely manual methods, mechanised operations produced substantial reductions in direct labour costs and project durations, and yielded measurable improvements in workmanship consistency and on-site safety. Over typical project life cycles, mechanisation demonstrated superior cost-effectiveness delivering lower life-cycle costs per unit of output and faster project delivery especially for repetitive, heavy-work activities (earthworks, concrete placement, lifting). Sensitivity analysis showed outcomes are most sensitive to equipment utilization rates and operator availability. The study concludes that strategic adoption of mechanical plants in public building works in South-East Nigeria is economically justified. Recommendations include targeted investment in shared/leased plant fleets, training programmes for operators and managers, procurement rules that incentivise life-cycle costing, and pilot mechanisation policies to scale benefits across the region.
Harrison Onyekachi Ugwu (Thu,) studied this question.