Journal of Civil Engineering Vol 68 No 2

Volume 68 Number 2 June 2026  Journal of the South African Institution of Civil Engineering 12 the results of a study or computation do not significantly change due to variations in underlying assumptions, they are consid- ered to be robust (Maverick 2021). Figure 10 illustrates the summary of the overall weights of the grades for each scenario. Scenario A incorporated professional registration as the fourth sub-criterion for the technical capacity criteria. Scenario B checked the effect of variations in the main criteria weighting. The plant and equipment and financial status criteria have equal weight as opposed to the technical capacity, experience, past per- formance, management capability, and health and safety. In scenario C, the effect of variations in the experience sub-criteria of weightings is assessed. Projects com- pleted by key staff are reduced by 50%, and company project completion is increased by 50%. Scenario D analysed the effect of variations in the past performance sub- criteria weighting. Scenario E checked the effect of variations in the main criteria weighting. This resulted in all the main criteria having equal weight. Scenario F incorporated leadership skills as a second sub-criterion for management capability criteria. Leadership skills are defined as the contractor’s ability to manage the pro- ject team, problem-solve, communicate, and negotiate, as indicated by Edum-Fotwe and McCaffer (2000). The results indicate that there is no significant change due to variations in underlying assumptions. The scenarios checked the effects of variations on the main criteria and sub-criteria. It is noted that scenarios B, C, D, and E have similar results for technical capacity, plant and equipment, and management capability criteria, and slight variations in other criteria. Scenario A and F also have similar overall weights in plant and equipment, with slight variations on the other criteria and sub-criteria. The overall project prior- ity vector of these scenarios is indicated in Figure 6. Contractor performance evaluation results As indicated in Table 7, the AHP depicts that, of the three contractor performance alternatives (refer to Figure 6), alternative 3 (experienced contractor) has the highest ranking, followed by alternative 2 (estab- lished contractor) and alternative 1 (emerg- ing contractor), respectively. Alternative 3 has the highest priority weight of 0.534, followed by alternative 2 (0.288) and alternative 1 (0.151). Thus, the weighting of an experienced contractor would be higher than the weighting of an established and emerging contractor. A sensitivity analysis was conducted on three different scenarios to check the reli- ability and robustness of the AHP results achieved. The results indicate that there is no significant change due to variations in underlying assumptions. TOWARDS THE DEVELOPMENT OF THE GRADING AND PERFORMANCE ASSESSMENT FRAMEWORK In developing the framework, the results of the comparison matrix for AHP, which involved pairwise comparisons between the sub-criteria in relation to each main criterion, were utilised. Weight allocation To determine the weight of the sub-criteria for academic qualifications, the following assumptions were applied. The overall weight obtained for the sub-criteria in level 2 of the AHP hierarchy (Figures 5 and 6) was divided by the number of criteria. For example, academic qualification is subdivided into five criteria, as shown in Table 8. The weight of the criteria (0.633) was divided by 5, which equals 0.1266. To get the criteria for the lowest qualification, the value obtained (0.1266) was further divided by 2 because the first lowest quali- fication is the second after no qualification. Thereafter, the same answer would be added to get the next higher level. The formula is as follows: Weight of academic qualifications = 0.633 (from level 2 of the AHP model Table 8 Weights of the academic qualifications sub-criteria Technical capacity Academic qualifications Weight Key staff experience Weight Number of key staff Weight No certificate 0 0 years 0 0 0 Certificate 0.0633 0-2 years 0.026 1 0.0106 Diploma 0.1266 3-5 years 0.052 2 0.0212 Degree 0.1899 5-10 years 0.078 3 0.0318 Postgraduate 0.2532 More than ten years 0.106 More than 3 key staff 0.0424 Total 0.633 0.260 0.106 Table 7 Overall weights of contractor performance assessment alternatives Priority matrix for contractor performance Overall project priority vector V Main criteria priority vector Alternatives Technical capacity Experience P&E Financial status Past performance Management capability OHS Technical 0.380 1 0.273 0.064 0.064 0.086 0.079 0.064 0.098 0.151 Experience 0.199 2 0.318 0.267 0.267 0.272 0.271 0.267 0.275 0.288 P&E 0.038 3 0.408 0.669 0.669 0.641 0.650 0.669 0.627 0.534 Financial status 0.071 Past performance 0.199 Management capability 0.023 OHS 0.090