A formal model for construction safety and health risk management

Despite recent efforts to improve site safety, construction still accounts for a disproportionate injury and illness rate. According to the 2007 injury and illness data released by the National Safety Council, the construction industry has a fatality and disabling injury rate that is approximately three times higher than the all-industry average. The transient, unique, and complex nature of construction projects makes safety management exceptionally difficult. Most construction safety efforts are applied in an informal fashion under the premise that simply allocating more resources to safety management will improve site safety. Currently, there is no mechanism by which construction site safety professionals may formally select safety program elements for a particular process. This dissertation describes a research effort that introduces, populates, and validates a formal method to evaluate construction safety risk and strategically match safety program elements to construction processes. The decision scheme introduced, based on the application of Newton’s third law, assumes that every construction activity is associated with specific safety risks and that each safety program element is capable of mitigating a portion of such risks. Using the high-risk process of constructing concrete formwork as an example, the theoretical model was populated. Data was obtained using the Delphi method, a systematic and interactive research technique for obtaining the judgment of a panel of independent experts. The results of this research include the quantification of probability and severity values for ten mutually-exclusive and all-inclusive safety risks associated with thirteen worker-activities required to construct concrete formwork. Additionally, the study quantified the probability and severity reduction values resulting from the implementation of thirteen safety program elements. The data can be used to improve safety management techniques in several ways. First, cumulative risk may be tracked throughout a work period allowing safety managers to identify and avoid periods of exceptionally high safety risk. Second, safety managers may strategically select safety program elements based on the ability to reduce portions of specific risks. Finally, the balance between cumulative risk and the safety mitigation can be evaluated. The results of this research indicate that the highest risk activities for formwork construction are form lubrication and preparation, ascending and descending ladders, and accepting and loading materials with a crane. The most effective safety program elements are upper management support and commitment, subcontractor selection and management, and employee involvement in safety management and planning. The risk values for formwork construction and the risk reduction values associated with safety program elements can be used to determine the appropriate scope and focus of safety and health management efforts. The methods used to quantify these values may be applied to any construction process or safety program.