Rollover protection structure

A rollover protection structure or rollover protection system (ROPS) (/roʊps/ or /ˌɑːroʊpiˈɛs/) is a system or structure intended to protect equipment operators and motorists from injuries caused by vehicle overturns or rollovers. Like rollcages and rollbars in cars and trucks, cabs, frames or rollbars on agricultural and construction equipments, a ROPS involves mechanical components attached to the frame of the vehicle that maintain a clearance zone large enough to protect the operator's body in the event of rollover.

Commonly found on heavy equipment (i.e. tractors), earth-moving machinery and UTVs used in construction, agriculture and mining, ROPS structures are defined by various regulatory agencies, including US Occupational Safety and Health Administration (OSHA) and international standard organizations such as ISO and OECD. 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 operator's compartment for ROPS purposes.

ROPS are commonly fitted to 4x4s, pickup trucks, earth moving equipment, soil compactors and utility vehicles used in the mining industry. Products such as this were developed out of necessity so employees travelling around or within mine sites were provided with extra protection in the event of a fleet vehicle rollover.

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 International Organization for Standardization has guidelines for destructively testing ROPS structures on earthmoving machinery, excavators, forestry equipment and tractors. Theoretical performance analysis of major new design ROPS is not permitted as an alternative to physical testing.

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^[when?] working with manufacturers to streamline the commercialization of this technology. The Division of Safety Research branch of NIOSH has developed cost-effective rollover protection structures (CROPS) for four tractor models (Ford 8N, Ford 3000, Ford 4000, Massey Ferguson 135), in an effort to provide safety for older model tractors.

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, shattering the rear window at the same time.

Tractor rollover has become one of the leading causes of occupational death in the agricultural industry. In the United States from 1992 to 2005, 1,412 workers were killed from tractor rollover, with roughly 10,000 suffering an injury. These rollover fatalities represented about 20% of all agricultural fatalities. During 2003 to 2010, 933 workers in agriculture, forestry, fishing and hunting industries were killed as a result of tractor rollover, accounting for over 63% of all tractor-related deaths. The National Safety Council estimates that between 150 and 200 tractor operators are killed due to rollover in the US each year. Researchers have also attempted to estimate the chances that a tractor rollover will result in a fatality of the operator. An adjusted probability of about 8 deaths per 100 tractor overturns (8%) was extrapolated using data from the Kentucky Fatality Assessment and Control Evaluation (FACE) Program. Furthermore, youth are particularly at risk of being crushed or pinned by a machine (all-terrain vehicle, tractor, etc.) that is not equipped with a rollover bar. All-terrain vehicles and tractors continue to be leading causes of fatal injury among youth in agricultural settings.

The installation of Rollover Protective Structures (ROPS) on older tractors that lack these protective devices has been identified as a viable solution for reducing overturn fatality rates among US farmers. When worn with a seat belt, these engineering controls are 99% effective in preventing operator death if an overturn occurs. The US National Institute for Occupational Safety and Health estimates that fatality rates from tractor overturns in the US could be reduced by a minimum of 71% if all tractors were equipped with ROPS. When paired with proper seat belt use on tractors, NIOSH estimates that ROPS could eliminate nearly all fatalities caused by tractor and lawn mower overturns. Without a seat belt, the ROPS is still 70% effective in preventing operator death, though there is a possibility that the rider may be thrown from the tractor during the overturn, and thus left unprotected by the ROPS.