vehicle crash compatibility

RACV position

RACV supports all cost-effective measures that are aimed at improving road safety. RACV supports further research into the causes of incompatibility between vehicles in crashes and the subsequent development of measures and regulations aimed at increasing compatibility levels.

An Australian Design Rule (ADR) governing the mandatory fitment of rear under-run guards on all new trucks and the introduction of an Australian Standard for Vehicle Frontal Protection Systems (VFPS or bull-bars) are supported.

effects of compatibility

In a 1998 Federal Office of Road Safety (FORS) study of compatibility, it was found that in a frontal collision between a 4WD and a small car, the small car driver was 17 times more likely to be killed than the 4WD driver. In the case of the front of a 4WD impacting into the side of a small car, the driver of the small car is 18 times more likely to die than the driver of the 4WD. Similar results have been reported other countries such as the U.S. by the Insurance Institute for Highway Safety (IIHS). These figures suggest compatibility is an important issue in road safety and one worthy of increased attention.

compatibility in vehicle crush management

When two vehicles collide head on, both vehicles must absorb the energy of the collision. This occurs when each vehicle's frontal structure is crushed. This can result in a high risk of injury to the occupants of a small vehicle, when it collides with a large vehicle. This is due largely to the frontal structure of a 4WD typically being much stiffer than that of the smaller car. The result is often excessive intrusion into the smaller car's cabin.

According to research conducted by Renault, it is possible to design all cars to crush more evenly in a frontal collision. Such a move would potentially result in a safer car fleet worldwide.

vulnerable road users

This group includes pedestrians, cyclists and motorcyclists for whom protection in a crash is most difficult, due to their inherent lack of protection. Car designs take this group into consideration, mostly by providing a frontal design which is "more friendly" in a collision with them.

While crash tests recently began testing vehicles for pedestrian protection, there are as yet no vehicle regulations in Australia specifying a minimum protection level for pedestrians or other vulnerable road users.

large vehicle (truck) compatibility

Some of the most extreme examples of incompatibility are collisions between trucks and smaller as cars. It would be difficult to improve the crush characteristics of most trucks without reducing their mass.

Underrun guards prevent smaller vehicles from riding under the truck's structure. These are effective at the front, rear and sides of the truck. Many trucks already have these guards fitted and ADRs state that semi-trailers must have them fitted at the rear. However, this rule should be extended to all trucks and the feasibility of lowering their maximum height (presently 600 mm) examined, as should the feasibility of a similar rule for side underrun guards.

crashworthiness

Arguably the most effective way to improve compatibility is to improve vehicle crashworthiness. Given some of the difficulties surrounding the issue of reducing vehicle aggressivity (the risk to other vehicle occupants in a collision with a certain type of vehicle), crashworthiness should always remain the focus of vehicle safety improvements, including compatibility.

traffic engineering solutions

Another way of reducing the compatibility problem is by separating traffic through traffic control. This applies to separating oncoming traffic with divided highways, and potentially to the separation of trucks and cars through the use of dedicated truck/car lanes.

used car safety ratings

RACV is a stakeholder in the Used Car Safety Ratings (UCSR) program. This program ranks the relative crashworthiness of used vehicles on Australian roads. The latest UCSR release (August 2000) includes ratings for vehicle aggressivity. Conclusions that may be drawn from these results:

Larger vehicles tend to be more "aggressive" towards smaller vehicles in a collision between the two.
There is no significant correlation between crashworthiness and aggressivity. It would therefore appear quite possible to design vehicles to present an ideally low level of aggressivity and a high level of crashworthiness.

international harmonisation research activity

RACV, through the Monash University Accident Research Centre (MUARC) is a contributor to compatibility research conducted by the Safety Ratings Advisory Committee (SARAC) in Europe. The aim of SARAC is to coordinate vehicle safety research conducted by organisations around the globe.

compatibility in vehicle geometry

The wide variations in vehicle geometry (factors such as ride height, bumper height, seating position of occupants, body shape, width and length) seen on today's roads present a serious challenge to the goal of improving compatibility levels. While a passenger car may perform safely when struck by another car of similar geometry, the level of safety provided by the same car can be considerably less when it is struck at window height by a truck, for example.

It is not just trucks that pose a danger here. The recent trend towards a more diversified car fleet means there are now a lot more small cars and large 4WDs on the roads than ever before. The relationship between vehicle safety and geometry was examined by the Insurance Institute for Highway Safety (IIHS) in the U.S., which showed how changes in vehicle geometry such as ride height can significantly affect the outcomes of a collision.

what can be done to promote compatibility

There are a number of ways in which compatibility may be improved. These are listed by category below.

which types of road user compatibility applies

Compatibility applies to all types of road users and vehicles on the road. These include cars, trucks, vans, motorcycles, bicyclists, pedestrians, as well as all of their occupants and operators. A large part of the challenge compatibility presents is in finding an optimum solution that provides maximum benefit to all of these different groups.

conclusion

Determining how much of a problem vehicle compatibility presents and what are the best solutions is not an easy task. Possibly the most effective suggestion relating to compatibility is simply improving general vehicle crashworthiness, particularly for lighter cars. The sensitivity of vehicles to frontal geometry is one factor which would seem relatively simple to address. Height is arguably the most important geometrical factor. While crashworthiness has long been the focus of vehicle safety efforts, improving compatibility may be the next major challenge.