|M.Sc Thesis||Department of Civil and Environmental Engineering|
|Supervisor:||Assoc. Prof. Shapira Aviad|
Tower cranes command the greater part of construction sites, they hold great amounts of energy, and perform a wide range of hoisting and transporting tasks near and above people. Construction site safety is, therefore, closely related to the safety of working with tower cranes. Assisted by the "collective knowledge" of experts, a list of safety hazards was consolidated in a previous study, according to which a particular construction site with tower cranes can be characterized with respect to its safety risk level. Safety hazards that were identified and formulated serve as the basis for developing a quantitative-comparative method to evaluate the safety risk level of a given construction site in which tower cranes are used - the overall objective of this study. The first stage towards achieving this overall objective was to determine weights expressing the relative influence of each hazard on the total risk level of the construction site. No sufficiently large and detailed database of construction site safety events exists that enables statistical analysis. It was therefore decided to use a panel of well-experienced experts as a source of knowledge for the determination of the relative weights. To that end, a selected team of experienced and well-known experts was formed. Direct determination of relative weights of multiple factors is never an easy task, since the evaluation of each one of the factors cannot be done irrespective of the others and thus is very complex. In order to overcome this complexity, use was made of the Analytical Hierarchy Process (AHP). The second stage of the development process included defining indices for the evaluation of the size of each hazard at a particular construction site. Also, a formula was developed that served as a basis for the development of scales that transform the size of the risk factor into a risk level. At the third stage, a method was proposed that integrates the factor weights, factor sizes and risk levels into a total risk level at the construction site. Thus, development was completed of the general model. The model developed offers a quantitative-comparative evaluation of the safety risk level at construction sites with respect to the cranes' work. Development of the model emphasized the dominant hazards of the construction site, according to which the division of attention and resources required to deal with safety problems on construction sites can be determined.