# Improvements of Design for Safety in Construction through Multi-Participants Perception Analysis
## 4 Results and Discussion
### Relative Importance of the DfS Improvement Alternatives from the Overall Respondents' Perspectives
3.2 Relative Importance of DfS Improvement Alternatives from the Construction Project Designer's Perspective  
The designer graph in Figure 4 shows that the result of the designers' perception of the relative importance of the DfS improvement alternatives was similar to the result of all respondents' perceptions of the same. The designers, however, accorded greater importance to the 'Application of a design alternative' (0.147) compared to all other respondents. The designers think highly of the application of a design alternative because in South Korea, it is the contractor who selects design alternatives in the construction phase. Therefore, it is judged that as the designer wants to reflect the design alternative in the construction phase, thinking that the application of a design alternative is more important than the other alternatives. In contrast, the designer respondents considered 'Involvement of the contractor in the pre-construction phase' (0.097) as less important compared to all other respondents. This suggests that because conflicts may arise between the designer and the contractor due to a difference in opinion between them regarding the design progress in the design phase, the designer places less importance on 'Involvement of the contractor in the pre-construction phase'. 3.3 Relative Importance of DfS Improvement Alternatives from the Construction Project Contractors' Perspective  
The contractor graph in Figure 4 shows that the priorities of the contractor respondents in this study with regard to the DfS improvement alternatives were generally similar to those of all other respondents. Unlike all other respondents, however, the contractor respondents placed relative importance on the 'Development of a decision support system' (0.215). This may stem from the fact that the contractors may end up applying a DfS improvement alternative that is not suitable for the site conditions. Therefore, if the designer suggests a DfS improvement alternative considering the site conditions in the design phase through the decision support system, the contractor will be able to apply a suitable DfS improvement alternative in the field. In addition, the contractors accorded greater importance to the 'Development of a collaboration program' (0.117) compared to all other respondents. As mentioned earlier, in South Korea the contractor cannot participate in the design phase because DfS is implemented only in conventional design-bid-build projects. For this reason, the contractor respondents recognized the need for the development of a collaboration program. Meanwhile, the contractors placed less importance on the 'Application of extended coverage' (0.047) compared to all other respondents because coming up with a DfS improvement alternative is not a prerequisite, and the commencement of construction may be delayed due to the extension of the design period. The numbers within parentheses are the ranks of the alternatives, the numbers shaded in grey are the highest ranked criteria, the boldface and italicized numbers are weighting factors that exceed 0.20, the boldface numbers are the weighting factors that exceed 0.15, and the italicized numbers are the weighting factors that exceed 0.10. 3.4 Relative Importance of DfS Improvement Alternatives from the Construction Project Construction Managers' Perspective  
The construction manager graph in Figure 4 shows that the construction manager respondents in this study accorded greater importance to 'Involvement of the contractor in the pre-construction phase' (0.250) compared to all other respondents, possibly because the construction manager is responsible for the management of the construction site as an agent of the client, and this person investigates if the contractor has taken the risk mitigation measures established in the design phase. If the contractor participates in the implementation of DfS in the pre-construction phase, the contractor discovers the risk factors and establishes risk mitigation measures along with the designer.