What makes a safety control "enough" for high-energy hazards? Defining and testing acceptable alternative controls when a Direct Control is not feasible.

INTRODUCTION: Serious injuries and fatalities (SIFs) in construction have remained stubbornly high despite substantial safety efforts. Prior research suggests that these events frequently arise in contexts where controls are absent, ineffective, poorly defined, or inconsistently implemented. Prevention appears to depend less on adding more controls and more on designing controls that are explicitly intended for SIF prevention, usable in the field, and precise enough to support consistent decisions at the point of risk. Within the energy-based safety framework, the concept of Direct Control has been introduced as a scientifically defined type of control for high-energy hazards with SIF potential. However, Direct Controls are not always feasible, leaving a recurring gap in practice: what constitutes "enough" control when high-energy hazards must be managed without a Direct Control? METHOD: This study addresses that gap through a two-phase research process. In Phase 1, an expert panel of 25 construction safety professionals participated in structured brainstorming, focus groups, and a modified Delphi method to develop a definition and criteria for Alternative Controls. The resulting framework specifies three categories and rules to ensure that Alternative Controls are timely, tangible, targeted, and reliably implemented at the point of risk. In Phase 2, a noise experiment with a separate group of 20 practitioners tested the framework's usability. Variability in adequacy decisions decreased by 47%, inter-rater agreement improved from fair to substantial (Fleiss' κ from 0.21-0.32 to 0.61-0.62), and practitioner confidence increased significantly (paired t-test, p < 0.001). RESULTS: Findings indicate that structured criteria for Alternative Controls can reduce decision noise and support more consistent, SIF-focused control decisions when Direct Controls are not feasible.