Single-Prime versus Multi-Prime Contracting: Impact on Performance Metrics in Road Infrastructure Projects - A Kenyan Case Study

This study explored the difference in performance metrics between single-prime contracting methods and multi-prime contracting methods in terms of Cost and overall performance (project’s financial, timeliness, overall quality, compliance with Safety and utilization of resources) as they are used in road infrastructure in Nairobi City County in Kenya. The study employed primary data collection using a Semi-structured Likert-Scaled questionnaire to collect data from professionals who have been involved in both contracting and methods of road construction in the County over the past 10 years. The study targeted a sample size of 385 out of which 267 respondents (69.4%) participated in the study. Purposive and snowball sampling methods were used to recruit and select the study participants. The Cronbach's alpha for contract cost overruns is 0.933, indicating the excellent reliability of the tool used to collect the data. With a Cronbach’s alpha of 0.615, overall contract performance demonstrated acceptable reliability. Inferential analysis of data collected revealed a statistically significant difference in construction costs between single-prime and multi-prime contracting methods (U = 798.00, z = 0.326, p= 0.017). The mean rank was higher for single-prime (42.71) compared to multi-prime (40.97), suggesting that single-prime projects tend to have higher costs. The analysis of construction costs revealed a statistically significant difference between single-prime (x̄=3.4286, σ=0.53385) and multi-prime (x̄=3.3735, σ=0.53785) contracting methods; t (81) = 0.461, p =0.006. The mean difference of 0.05504 (95% CI: -0.18277 to 0.29285) indicates that single-prime projects had slightly higher construction costs than multi-prime projects. The result suggests that single-prime contracting may actually be associated with marginally higher costs, possibly due to the prime contractor's markup on subcontractor work. This study concludes that multi-primes perform better than single-prime contracting methods in terms of cost and overall performance in large and complex road construction projects in Nairobi City County-Kenya Nairobi City County where a lot more technical expertise may be required.