The Mechanics of Slipping

Slips, trips and falls on the level are consistently the largest single cause of reported workplace injury, and they produce a disproportionate share of serious injuries — fractures, head injuries and long absences — particularly among older workers.

Slipping

A slip occurs when the friction between footwear and floor is insufficient for the force being applied. Five factors combine, and they are usefully remembered as a set because a slip almost always involves more than one:

• Contamination — water, oil, dust, food debris, ice, plastic sheeting, leaves. Even a very thin film of water reduces friction dramatically. This is the dominant factor in the great majority of slips.
• Floor surface — its roughness, and whether that roughness is adequate for the contaminant present.
• Footwear — sole pattern, compound and wear.
• Environment — lighting, glare, distraction, noise.
• Human factors — walking speed, carrying loads, using a phone, rushing, and reduced attention.

The critical insight

A floor that is perfectly safe when dry can be dangerously slippery with a barely visible film of water. Most slips are therefore contamination events rather than flooring events, which means the highest-value control is preventing contamination reaching the floor — not cleaning it up afterwards, and not warning people about it.

A wet floor sign is a warning that a control has failed. It is not itself a control.