Safety performance evaluation model for off-site construction through the integration of key leading and lagging factors

Off-site construction, a growing alternative to traditional building methods, offers advantages such as reduced environmental impact, improved productivity, and cost efficiency. However, off-site construction introduces new and unique safety challenges across its multiple phases of fabrication, transportation, and assembly. The Experience Modification Rating (EMR), a widely used insurance metric in traditional construction, remains the primary factor used by insurance carriers to adjust workers' compensation premiums for off-site firms. However, the industry's reliance on an outdated metric that relies on lagging safety indicators, broad classifications, and other nonsafety factors raises significant concerns over its applicability in reflecting the distinct safety risks and operational contexts of off-site work. Therefore, this research examines the inadequacies of EMR in this sector and identifies 70 key safety factors specific to off-site processes through an extensive literature review of 76 research publications. A structured survey was used to validate the relevance and importance of these factors and was distributed to professionals from both the off-site construction and insurance industries, yielding 30 valid responses. Based on the findings, this paper explores the potential for alternative safety evaluation approaches that are off-site-specific and data-driven and considers all relevant leading and lagging factors. Thus, using the Relative Importance Index (RII), this study establishes 36 validated, high-priority safety metrics, laying the groundwork for future multicriteria-based assessment models tailored to off-site construction. Additionally, applying the Mann-Whitney U test revealed significant intergroup differences in factor prioritization between off-site construction professionals and insurance providers, highlighting key divergences in safety perception.