Roll Over Protection Structure (ROPS) refers to operator compartment structures (usually cabs or frames) intended to protect equipment operators from injuries caused by vehicle overturns or rollovers.
Commonly found on heavy equipment (i.e. tractors) used in construction and agriculture, ROPS structures are defined by various regulatory agencies, including the US Occupational Safety and Health Administration (OSHA).[1] The regulations include both a strength requirement as well as an energy absorption requirement of the structure. Some dump trucks add a protrusion to their boxes that cover the operators compartment for ROPS purposes.
In the US, ROPS designs have to be certified by a Professional Engineer, who will normally require a destructive test. The structure will be tested at a reduced temperature (where the metal is more brittle), or fabricated from materials that have satisfactory low temperature performance.
The National Institute for Occupational Safety and Health (USA) believes that ROPS and proper seatbelt use on tractors can eliminate nearly all fatalities caused by tractor and lawn mower overturns.[2] (Without a seatbelt, the rider may be thrown from the tractor during the overturn, and thus left unprotected by the ROPS).[3] A recent Cochrane Systematic Review confirmed that in one Swedish study there was evidence that legislation mandating ROPS on new tractors decreased the fatality rate immediately and further reduced the rate over time. [4]
Some tractor operators have raised concerns about using ROPS in low-clearance environments, such as in orchards and buildings. In response, NIOSH developed an Automatically Deploying Rollover Protective Structure (AutoROPS) which stays in a lowered position until a rollover condition is determined, at which time it deploys to a fully extended and locked position. It is currently working with manufacturers to streamline the commercialization of this technology.[2]
Some automobile models have begun to adopt the phrase, substituting system for structure in the ROPS acronym, notably the Volvo C70 convertible models, and Jaguar XK. Their ROPS structures consist of two pyrotechnically charged roll hoops hidden behind the rear seats that will pop up in the case of a roll-over to protect the occupants. If the roof is up, the system will still work, in effect shattering the rear window at the same time.