Schäuble: The problem there is that conventional dummies usually cause much more vehicle damage than real humans. Furthermore, the impact usually takes place in a sideways standing position or sitting on a bicycle – we can therefore hardly use the values we measure with dummies developed for seated frontal impact. Thus, if experts were to look only at a vehicle’s damage after a crash test, they might perhaps draw the wrong conclusions in terms of vehicle speed based on that damage.
And the biofidelic dummy behaves differently?
Schäuble: In this respect, the biofidelic dummy is much more similar to a human being than a conventional dummy. The first models came onto the market about twelve years ago – at that time they were still comparatively primitive constructions with bones made of wood. Their sole purpose was to create a realistic impression of damage to the vehicle. At some point, it was discovered that the damage to a biofidelic dummy could also represent injuries to a human being – an approach I also pursued in my diploma thesis. In the meantime, damage to the biofidelic dummy is examined in exactly the same way as if it were injuries to real road users. By the way, a standard biofidelic dummy represents the average man – it weighs 78 kilograms and is 1.75 meters tall.
So what makes a biofidelic dummy so human-like?
Schäuble: The dummy has so-called bone substitute material. Its bones have a similar breaking strength to human bones. This means that they also break like real bones when subjected to comparable forces. The tissue substitute material, in turn, has pseudoelastic properties comparable to human tissue. Pseudoelastic means that if, for example, you press your finger into a human being’s abdomen, the fatty tissue gives way – if you take your hand away, it returns to its original shape. This is exactly the case with the biofidelic dummy – and is also a key prerequisite for the biofidelic dummy to interact with the test vehicle in the crash test in the same way a real person would in an accident. Conventional crash test dummies tend to be so-called elastic bodies – if you bump into them, they simply bounce away.
You have another very special qualification as an accident investigator: You are a certified AIS specialist. What does that mean?
Schäuble: AIS stands for Abbreviated Injury Scale. This is a measurement system that describes individual injuries to people by means of a precisely defined code. You can think of it as a dictionary – with currently around 4,000 entries. There is a code for each injury. A fracture of the tibia, for example, might have the code 854000.2, with the last digit after the period describing the severity of the injury. According to AIS, severe injuries rank at level 3 and above. In the US, the use of AIS is widespread. There, hospitals – such as trauma centers – must also code patients according to the AIS code. In Europe, on the other hand, AIS is less commonly used today.
What does this certification mean for your work? What is it good for anyway, if AIS is not very widespread in Europe?
Schäuble: For accident research in particular, it is important to precisely code the injury and its severity. This makes it easier to work with databases and communicate with other scientists. It was important to me that DEKRA Accident Research can also present the relevant expertise to the outside world – if we are active in AIS, then this is backed up by the AIS certificate. In Germany, we work with AIS as part of the GIDAS database (German In-Depth Accident Study). GIDAS is a joint project of the Federal Highway Research Institute (BASt) and the Research Association of Automotive Technology (FAT), of which DEKRA is also a member. Accident research, however, should not only be considered on a national level. After all, many vehicle models are driving on roads the world over. In addition, international comparison helps to identify strengths and weaknesses specific to a vehicle’s country or region. This presupposes that the players speak the same language.