Background Owing to high injury rates, safety interventions are needed in the construction industry. Evidence-based interventions tailored to this industry are, however, scarce. Leader-based safety interventions have proven more effective than worker-based interventions in other industries.

Objective To test a leader-based safety intervention for construction sites. The intervention consists of encouraging safety coordinators to provide feedback on work safety to the client and line management. The intention is to increase communication and interactions regarding safety within the line management and between the client and the senior management. It is hypothesised that this, in turn, will lead to increased communication and interaction about safety between management and coworkers as well as an increased on-site safety level.

Setting A group-randomised double-blinded case study of six Danish construction sites (three intervention sites and three control sites). The recruitment of the construction sites is performed continuously from January 2010 to June 2010. The investigation of each site lasts 20 continuous weeks.

Methods Confirmatory statistical analysis is used to test if the safety level increased, and if the probability of safety communications between management and coworkers increases as a consequence of the intervention. The data collection will be blinded. Qualitative methods are used to evaluate if communication and interactions about safety at all managerial levels, including the client, increase.

Outcome measures (1) The proportion of safety-related communications out of all studied communications between management and coworkers. (2) The safety level index of the construction sites.