## 2 Literature Review
### Prequalification Criteria  
Contractor selection research often focuses on developing methods and tools similar to supplier selection. In these types of studies, emphasis has been placed on investigating clients' criteria in contractor prequalification and selection. [PERSON] et al. [25] established a hierarchical structural model attempting to understand the preemptive qualification criteria and their links to contractor performance. Their model adopts 29 technical attributes over five confirmatory factors according to structural equation modeling: overall project success (OPS), past performance (PP), quality performance (QP), planning and control (PC), and soundness of business and workforce (SBW). [PERSON] and [PERSON] [26] stated that contractors' quality performance is typically gauged by safety, query response time, quality assurance programs and quality control, safety records, tender timeliness, and tender quality. [PERSON] et al. [27] developed a framework based on 12 criteria to evaluate sub-contractor performance. [PERSON] and [PERSON] [5] found substantial variation in contractor selection criteria expression and classified the criteria into five categories: reputation, safety, managerial capability, technical ability, and financial soundness. A wide variety of criteria have been proposed based on the literature (Table 2). Although contractor prequalification has common characteristics, distinct projects can exhibit different criteria. The following 12 criteria are most considered in prequalification:  
* Financial stability (C1): The general financial situation and performance of a contractor must be known to the contracting authority;
* Credit rating (C2): A credit rating indicated the probability that a company or government entity will become insolvent. It is usually performed by a credit rating agency;
* Engineering experience (C3): The contractor must demonstrate previous participation, especially in similar bidding projects;
* Personnel qualification (C4): The qualification of personnel requires adequate knowledge of the technical principles underlying the nondestructive tests to be performed;
* Engineering ability (C5): Engineering ability is a professional discipline that addresses the designing, planning, construction, and managing of infrastructure;
* Performance and quality (C6): Quality affects project performance. Defects or failures in constructed facilities require reconstruction and can result in degraded operations and high costs;
* Project management organization (C7): This ensures that required tasks are completed in a timely manner and reports a company's business requirements and staffing levels; \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Methodology**} & \multicolumn{3}{c}{**Principal Characteristics**} \\ \cline{2-3}  & **Known Usage** & **Degree of Subjectivity** \\ \hline Bespoke methods & Profile amongst industry practitioners & Input and output very subjective \\ \hline Multiattribute analysis & Simple scoring models used by industry, some & Input reliant upon subjective evaluation of attributes \\  & usage by academia & Input converts qualitative data to quantitative \\ \hline Multiattribute utility theory & Evidence of academic usage & Achieving interval data prone to \\  & Evidence of academic usage & subjective evaluation \\ \hline Cluster analysis & Limited & None of the raw multivariate data are used \\ \hline Fuzzy set theory & Evidence of academic usage & Scope for development of attribute profiles \\ \hline Multivariate discriminant analysis & Previous usage & Quantitative \\ \hline General performance model & Evidence of academic usage but in other areas &
\begin{tabular}{c} Combines subjective inputs and \\ empirical information \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of contractor selection methodologies (Adapted from [PERSON] ([PERSON] 1998)).