Staying on Track

The question of whether a crash barrier or a wall provides better protection depends on two factors: the speed and the possible impact angle of the race car. For instance, in Monaco: the city track is lined with 32 kilometres of crash barriers for the Formula 1 Grand Prix. There is also a number of walls – for example, at the ‘Nouvelle Chicane’ – to protect the spectators positioned close to the track. However, it is the crash barriers that actually restrict the track. There are two reasons for this: on the one hand, they are easier to assemble, and on the other hand, the race in Monaco tends to be driven at relatively low speeds. Therefore the crash barriers are adequate to catch the car in the event of a collision. In the few places where there is a risk of head-on impacts at high speed, such as at the exit from the tunnel, the track is secured with bolted tyre stacks tied together with elastic rubber straps.

Walls are used to restrict the track primarily on oval circuits such as the ‘Brickyard’ at Indianapolis. Here, the danger of a frontal impact is less than on the typical Formula 1 circuits with their hairpin corners and chicanes. In the event of an accident, the cars – travelling at over 300km/h – slide along the concrete wall until the energy has been absorbed.

To reduce the danger in a frontal impact engineers at the University of Nebraska in the USA have developed so-called ‘soft walls’. These ‘soft walls’, used for the first time at Indianapolis in 2002, consist of modules roughly six metres in length. Directly on the track, four rectangular steel pipes are assembled above each other, welded into a single unit and then attached to the concrete wall behind with metal cables. Between the wall and the pipes, there are piles of a synthetic material similar to polystyrene, compressed into sheets.

“The principle behind the wall is that it provides a continuous barrier system that will remain parallel to the track and move back as a unit as it dissipates energy,” says Dr. Dean Sicking, director of the Midwest Roadside Safety Facility at the University of Nebraska. “The need for that movement is to prevent pocketing, which is where the barrier wraps around the front of the car, which increases deceleration extremely.”

The system at Indianapolis, known in the USA as ‘SAFER’ (Steel and Foam Energy Reduction), has already proven its value at races in the US NASCAR series and the Indy Racing League. Apart from the flexible reaction, which improves the energy absorption dramatically, it also offers the advantage of returning to its original form after the impact – it does not need to be repaired or replaced.

The ‘soft walls’ were optimised during thousands of hours' work on the computer and then subjected to a series of crash tests on a test circuit. For the Formula 1 race at Indianapolis, ‘SAFER’ protects the entrance and the exit of the banked corner, which is driven at up to 350km/h. Tests are currently being carried out to see whether the barrier can be used at other Formula 1 tracks. One point is clear: in Formula 1, flexible solutions are required for improving safety.

Flexible solutions, which adapt ideally to the local features, are also a crucial element in terms of passive safety in normal road traffic. The road ought to ‘forgive’ mistakes as much as possible, so that a ‘little’ driving mistake does not lead to a serious accident. This means that it should be possible to use open run-off zones and road shoulders for evasive manoeuvres in an emergency. It also means that drivers should be protected from obstacles, especially trees.

“The crash safety of vehicles is often pushed to the limit, especially in a side impact against an obstacle,” says Dr. Christoph Lauterwasser from the Allianz Centre for Technology (AZT) in Munich. “The seriousness of accidents involving trees can be reduced considerably by using crash barriers. However, there must be enough room for the crash barrier to be deformed; after all, it is supposed to absorb some of the impact energy. But – after all, the best protection is always an adequate speed.”

Passive protective devices cannot prevent accidents, but only reduce the consequences. Therefore, new approaches are currently being researched to increase the level of active driving safety: electronic stability programmes could form the basis for future warning systems, which constantly probe the environment of the car and make specific interventions into the driving dynamics to keep the car on the road.

However, doubts immediately arise when one considers that race cars could possibly be fitted with such innovations. It seems unlikely that Formula 1 drivers will be allowed to enjoy this level of active safety.