Energieverbrauch, Luftverschmutzung und der lokal begrenzte Raum im Nahverkehr rufen nach leichten und damit energieeffizienten Autos. Ein grosses Problem war bisher die unzureichende Sicherheit von sehr leichten Personenwagen. Dabei wird aber oft vergessen, dass nicht nur die physikalisch bedingten Masseneffekte, sondern vor allem die Heute zu wenig Steifen leichten Beziehungsweise die zu steifen schweren Personen- und Geländewagen für dieses Sicherheitsproblem verantwortlich sind. Zwar haben Crashtests mit 44 km/h und 50 Prozent Überdeckung gegen eine harte Mauerecke in den letzten Jahren erfreulicherweise zu stabileren Frontstrukturen von zahlreichen Kleinfahrzeugen geführt. Umgekehrt hatte aber dieser gleiche inoffizielle Crashtest zur folge, dass auch schwere Fahrzeuge immer steifere Frontstrukturen haben "mussten", um den Test zu erfüllen. Dies führt unguenstigerweise dazu, dass dann im realen Lollisionsfall kleine, "weiche" Fahrzeuge noch stärker belastet werden als früher. Insofern hat dieser theoretisch sinnvolle Ansatz eines härteren Strukturtests auch zu einer Verschlechterung der Sicherheit für Kleinfahrzeuge geführt. Das vor diesem Hintergrund 1991 begonnene Forschungsprojekt der Züricher Hochschulen sowie der Ingenieurschulen Biel und Winterthur "Sicherheit von Leichtfahrzeugen", konnte bereits mit den ersten Crashtest im Jahre 1991 zeigen, dass einerseits bei handelsüblichen Kleinstfahrzeugen schwere Sicherheitsmängel bestanden, dass aber andererseits in einem ersten Schritt die Sicherheit mit relativ bescheidenen Mitteln deutlich verbessert werden konnte. Weitere systematische Verbesserungen an der Struktur und an den Rückhaltesystemen liessen mehrere neu konzipierte Kleinstfahrzeuge, und im Jahre 1996 das 650 kg schwere Experimental-Leichtfahrzeug cratch entstehen. Unter sehr hoher Fahrzeugbelastung beim Crash gegen ein doppelt so schweres Fahrzeug wurden bei einer Geschwindigkeitsänderung von über 70 km/h bei den Versuchspuppen nur unbedenkliche Messwerte ermittelt. Neben diesen Arbeiten zur Verbesserung der passiven Sicherheit bei Frontalkollisionen wurden zahlreiche Studien im Hinblick auf Seiten- und Heckkollisionen sowie Fussgängerkollisionen und die aktive Sicherheit durchgeführt. (A) English abstract: High energy consumption, air pollution and local traffic congestion call for the development of lightweight and thus energy efficient vehicles for use in city areas. Such developments have so far been impeded by the insufficient collision safety offered by these vehicles. Crash test configurations such as the frontal offset test against a rigid barrier unfortunately lead to stiffer frontal structures of heavy cars. This is one of the reasons why accident statistics today show a safety deficit for the occupants of small, lightweight vehicles. However, it is often overlooked that not only the vehicle mass itself, but also the incompatibility between stiff frontal structures of heavy cars versus 'soft' structures of lightweight vehicles is responsible for this disadvantage. The project 'Safety of Lightweight Vehicles', initiated in 1991 by several Institutes of the University of Zürich, the ETH Zürich, and the Engineering Schools of Biel and Winterthur, is now concluded. Switzerland as a country that does not produce cars could act flexibly, using the existing know-how in accident investigation, biomechanics, light weight construction and electronics. Additional know-how has been accumulated over the past six years by the 5 - 6 engineers (on average) involved in the project. When, in 1990, the project team decided to take an initiative in view of an improvement of the safety of low mass vehicles (LMV's), the general belief was prevailing in the automotive industry as well as in the public opinion that small and low mass vehicles could not exhibit an adequate safety performance a prior due to basic physical principles. Ecologically motivated promoters of LMV's furthermore were under the wrong impression that such vehicles were associated with no substantial safety problems as a result of the limited travelling speeds these vehicles are capable to attain. Accordingly, this group of persons did not consider an improvement of the safety standards of LMV's a general necessity. First crash tests made in1991 were aimed at increasing the awareness of the public opinion and of the automotive industry to the problem rather than at providing in-depth technical and scientific knowledge. The results however clearly showed the defective safety performance of commercially available LMV's and documented the large margin for improvements in that vehicle safety could be substantially improved in an exemplary fashion using only simple means. On the basis of systematic improvements and advanced concepts with respect to vehicle structure and occupant restraint methods, in 1996 a LMV could be presented which exhibited a superior safety performance in a severe crash test with a velocity change of as much as 70 km/h. All measurements made on the anthropomorphic test devices were within tolerance limits during this crash, although the test substantially exceeded present standards with respect to severity, a result which had been held unreachable before by experts. During this research phase certain progressive automobile manufacturers initiated the development of safe small vehicles. This fact also helped to reemphasize the old but partly forgotten requirement of vehicle compatibility. In addition, various research studies, e.g on lateral and rear-end impacts, collisions against pedestrians, and possible improvements in active safety have been performed. The fruitful cooperation with these vehicle manufacturers and with suppliers of safety components is a possible contribution to the fact that already in 1998 first small and safe vehicles will be available on the market. It remains to be hoped that these vehicles will not be adversely tagged as "mini-racing cars" by marketing strategies suggesting aggressive and "sporty", i.e., fast driving habits. In such a fashion the large engineering expense involved in safety improvement would in turn be offset by increased injury risks for occupants and external traffic participants. The high passive safety standard can only become effective in a collision if the limits imposed by physics as well as by human injury tolerance are kept in mind. (A)
Abstract