Integrative model for quantitative evaluation of safety on construction sites with tower cranes

The gradual disappearance of traditional borderlines between equipment cultures and the increasing use of tower cranes as today's dominant building construction equipment result in exposure to safety issues concerning tower crane operation that have not yet been fully addressed. This paper proposes a model capable of computing an overall index that realistically reflects the safety level on any individual site due to the operation of tower cranes. The model integrates four modules: (1) nonsite-specific relative weights of safety factors, (2) measurement of the magnitude of each safety factor actually present on site, (3) scales to convert each measured magnitude into a value representing the potential risk generated by each factor present on site, and (4) multiplying factors to convert the cumulative risk generated by all factors into actual risk. The model was computerized and tested on two construction sites and the user interface for company and site data gathering was validated. The development of the model builds on expert judgment and as such, its potential application in other construction cultures would require due adjustments, which are made possible by its modular architecture and content transparency.