Crash test dummy

Adult safety

EXTRA INFORMATION

Improving rear seat safety

WHAT WE KNOW

Background

Historically the rear seat has been seen as being the safest place in a car. However there have been dramatic improvements in vehicle safety and the regulations and consumer information programs that have driven these improvements have largely focused on the crash protection to drivers and the front seat passengers. As a result, we have observed a much lower uptake of safety technologies in the rear seat of modern cars.

The one safety technology that is available in all seating positions in a car is the seat belt. Seat belts are extremely effective in reducing the risk of death and serious injury and every one should always use a seat belt whenever they travel in a car. Seat belts work by tying the passenger to the vehicle so that the passenger gets the full benefit of crumple zones engineered into modern vehicles, they prevent passengers from being ejected and minimise the possibility of the passenger coming into contact with other objects and hard surfaces in the vehicle. In this way they greatly reduce the risk of death and serious injury. However in restraining a passenger in a crash they also generate some loads on the passenger’s body. Seat belts are designed to apply these loads to the strongest parts of the body – the bony skeleton. But to apply these loads to the bony skeleton effectively the seat belt must be positioned over the skeleton correctly – this is why it is important to always use a seat belt correctly and that the seat belt fits the passenger properly.

As we age, we become less tolerant to the loads applied to our bodies by seat belts in a crash. While seat belts continue to provide even the oldest occupants with effective crash protection, they can be a source of injury for some older people in some crashes. In other words, the seat belt will prevent the most serious life threatening injuries, but in doing so, they might produce some more minor injury. For younger people these are much less severe injuries, but for the oldest passengers these minor injuries have the potential to cause more serious complications. There is a need to understand how older people use seat belts to ensure they are using them in the best possible way. There is also a need to identify the best new technologies that can be incorporated into seatbelts to minimise this risk of chest injury to the oldest passengers.

Our research

Rear seat safety

We have examined the relative risk of injury in front and rear seat positions for passengers of different ages. We have also examined differences in injury outcomes for front and rear seat passengers in crashes in NSW. Using in-depth crash investigation we have also identified the detailed sources of injury to rear seat passengers of different ages. Finally we have examined methods for assessing the protection provide to rear seat occupants using simulated laboratory crash tests, and examined how existing technologies, commonly employed in front seat positions might help to reduce injury risk for rear seat passengers.

Older driver safety

As part of our collaborative work with the George Institute for Global Health, we have studied seat belt use in 380 drivers aged 75 years and older. We have done this by talking to these drivers, and observing them in their own vehicles.

What we have found

Our research has demonstrated that rear seat safety has not improved as much as the rear seat, and for adults, the relative safety in the rear seat is less than what is was in older model vehicles. We have also demonstrated that one in five passengers admitted to hospital following a crash in NSW was seated in the rear seat of the vehicle. The pattern of injury is also different between those injured in the front and rear seat, and this pattern varies with the age of the occupant. Our data suggests that many people in the rear seat may not be achieving a good seat belt fit, and in part because of this, the seat belt is often the primary source of injury among rear seat occupants. As explained above, rear seat occupants should continue to use their seat belt because this is protecting them from more serious injury. However our research demonstrates the need to improve the fit of seatbelts for all occupants using the rear seats (who are too big to use dedicated child restraints) as well as introduce enhanced technologies to better manage the loads applied to the body. This work is informing strategies and programs in Australia and elsewhere to encourage more attention to safety of the rear seat. This includes the inclusion of rear seat safety ratings in consumer information programs likes NCAP.

In our study of seat belt use among older drivers, we have seen that like most Australians, most older drivers always use their seat belt when they travel in a car. However we have found that many older drivers have trouble achieving a good seat belt position. This is because many older drivers are not aware of the features in their vehicles that could improve their seat belt fit. This includes sash belt height adjustment features, as well as features to modify the height of vehicle seats. Older drivers need to be more aware of the importance of always keeping the sash part of the belts over the mid portion of their shoulder, and keeping the lap part of the belt low across their pelvis.

We have also found that many older drivers report comfort problems when using seat belts. This might be related to poor seat belt fit, but our recent research suggest this might also be more likely in older drivers who suffer from chronic conditions affecting their physical function. This includes things like osteoporosis and chronic pain. Many older drivers commonly use cushions and other comfort accessories when they travel in cars, and some of these may have a negative impact on the crash protection provided by a seat belt. We are currently working with our collaborators at the George Institute for Global health to develop guidelines for the use of these comfort accessories.

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