Slipping on Concrete: a Case Study


Barnett, RL, Ziemba, AAE, & Liber, T. “Slipping on Concrete: A Case Study.” Proceedings of the ASME 2009 International Mechanical Engineering Congress and Exposition. Volume 13: New Developments in Simulation Methods and Software for Engineering Applications; Safety Engineering, Risk Analysis and Reliability Methods; Transportation Systems. Lake Buena Vista, Florida, USA. November 13–19, 2009. pp. 359-371. ASME.


The notion of slipperiness is rarely associated with a concrete walkway. The aggressive nature of this surface invariably satisfies the classical criterion of a safe floor. The case study described in this paper challenges this preconception. It involves a woman who enters an indoor stairwell of a parking lot and slips on the dry concrete landing while approaching the stairs with her arm outstretched to grasp the railing. The current state-of-the-art of human slipping provides this victim with no remedy at law. This paper presents a forensic and safety study that focuses on slip and fall. Slip is usually analyzed by a classical system that has no redeeming features. This protocol provides a go/no-go criterion that proclaims a walking surface safe if its interaction with a surrogate material (e.g. leather) produces an average coefficient of friction greater than 0.5. It turns out that many walkers slip on such mythical “safe” floors. The subject case adopts a modern theory of human slipping that quantitatively predicts the number of walkers who will slip on a given surface including concrete landings.

Keywords: Safety Engineering, Risk Analysis and Reliability Methods, Concretes, Forensic sciences, Friction, Safety, Stairs

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