Contractors’ selection criteria for sustainable infrastructure delivery in Nigeria

The research reported in this study developed and validated a framework for the pre-evaluation of contractors for sustainable infrastructure projects through Public-Private Partnership (PPP) in Nigeria. The proposed framework uses the Analytic Network Process (ANP) to select contractors for build-operate-transfer (BOT) contractors. Theoretically grounded on a system theory, a sustainable infrastructure delivery (SID) model is developed in this research. One of its important features is the ability to solve complex
decision problems, typical of a decision-making process that involves selection of contractors for PPP projects. At the deductive phase of the proposed model is the integration of the ANP (multi-criteria decision-making technique) for data synthesis. An extensive literature review was conducted with regard to selection criteria for contractors. Furthermore, a web-based questionnaire survey was undertaken, aimed at capturing the perception of the Nigerian construction professionals regarding the importance of these criteria
for pre-evaluation of contractors for public infrastructure procurement. A total of 143 questionnaires was received and their feedbacks were analysed with the IBM SPSS statistical
package. The findings revealed a broad range of 55 relevant criteria that were linked to sustainable contractor selection. Through the application of factor analysis, the number of the criteria was reduced to 16, after multicollinearity issues in the data set had been resolved.
The 16 factors were modelled to pairwise comparison matrices, transforming decision making process from linear to a systemic approach. A purposeful sampling methodology was then
applied for the selection of decision-making panel (DM), who completed the pairwise comparison survey. The survey results were synthesised by ANP. The final solution derived
order of significance of the two categories of contractors- multinational construction corporations (MCC) and local construction contractors (LCC) in respect to the delivery of a sustainable infrastructure. Sensitivity analysis of the research findings reveals that the 16 criteria have differential comparative advantages, which requires critical judgement during contractors’ pre-evaluation process. Although the overall priorities rank multinational construction corporations (MCC) higher than local construction companies (LCC), it is not absolute that MCC will deliver a better value for money on all tangible and intangible elements of sustainable infrastructure
attributes. LCC outperform on some of the key criteria such as local employment creation and local material sourcing, which are essential pre-evaluation criteria. This research proposes a novel framework to harmonise sustainability indicators in contractor selection and offers a new theoretical insight into the approach to contractors’ selection criteria during pre-evaluation process, which contributes to the enhancement of PPP delivery in
Nigeria. Overall, the proposed SID model has demonstrated the need for a shift in the modus operandi of the government’s ministries, department and agencies (MDAs) in Nigeria from
unidirectional to systemic selection techniques. It clearly demonstrates the appropriateness of the ANP to predict the contractor that will deliver more sustainable infrastructure.