描述了五阶段建筑生产力计划第四阶段的活动和结果，讨论了研究团队对钢铁行业创新和最佳实践的关注，对创新劳动力发展过程的调查，以及对CII最佳实践生产力提高指数（BPPII）的验证。介绍了该团队对几个快速连接钢系统生产商的生产率数据的独立分析、对承包商劳动力发展指数（CWDA）潜在用户的调查结果、对与钢铁生产率相关的CII最佳实践的识别，以及对BPPII的持续验证。这些研究活动的结果表明，快速生产带来了显著的生产力效益- 连接系统确认了CWDA的价值，确定了一套与机械、电气和混凝土行业的生产率提高实践一致的钢铁生产率最佳实践，并进一步验证了BPPII。

Describes the activities and results of the fourth phase of the five-phase Construction Productivity Program, discussing the research team's focus on innovations and best practices for the steel trades, its investigation of an innovative workforce development process, and its validation of the CII Best Practices Productivity Improvement Index (BPPII). Presents the team's independent analysis of the productivity data from several producers of quick- connection steel systems, the results of its survey of prospective users of the Contractors' Workforce Development Index (CWDA), its identification of CII Best Practices that are correlated to steel productivity, and its continuing validation of the BPPII. The results of these research activities showed significant productivity benefits from the quick-connection systems, affirmed the value of the CWDA, identified a set of best practices for steel productivity consistent with the sets of productivity-enhancing practices for the mechanical, electrical, and concrete trades, and further validated the BPPII.