2006 Issue

www.utahengineerscouncil.org 20 UEC JOURNAL February 2006 A utomobile crashes are rou- tinely investigated by local police authorities whose duties include securing the accident scene and coordinat- ing rescue efforts, recording the physical evidence, interviewing eye witnesses, issu- ing citations for infractions of the local traf- fic laws, determining any potential crimi- nal offense, determining accident causation and often assigning fault. Investigation and assessment of automobile accidents beyond the scope of the police’ duties arises from various needs including insurance subroga- tion, assessment of vehicle-component per- formance, injury causation, research for de- sign improvements, and civil law suites. Thus, there is a growing need for trained automobile accident reconstruction experts who have special knowledge, training or experience necessary to assess certain acci- dent and vehicle related issues more spe- cifically and comprehensively. When faced with a potential citation and fine for not wearing a seat belt, some drivers and passengers will choose to claim that they had been wearing the seat belt during the accident even when they actu- ally were not (see utahsafetycouncil.org for current law). Assessment by the police of seat belt usage in an accident is typically based on a number of on-scene observations including apparent occupant injuries, final position of the occupant, post-collision condition of the seat belt restraint, and the driver/passenger statements. The final conclusion of seat belt usage as noted in the accident report results from the judg- ment of the officer who often must com- pare the physical evidence with the state- ments of thewitnesses. For example, if there is clear evidence that the seat belt was not worn in the crash – such as an ejected oc- cupant – then the physical evidence “speaks for itself” regardless of what the driver/passenger says. However, when there isn’t enough solid physical evidence regarding usage either way, the conclusion is usually simply based on the witness’ state- ment. Conversely, in certain crashes when the seat belt itself appears to be the only remaining source to potentially determine whether or not the seat belt was worn, a cursory visual inspection of the compo- nents is typically conducted by the officer. Such an examination may include observ- ing if the webbing is permanently ex- tended, verify that the restraint in ques- tion operates normally, or examination of the webbing for any obvious indications of stress on the webbing or routing hard- ware. Sometimes the collision is such that the direction of forces and impact severity is not going to produce occupant loading to the point of causing clear indications on the seat belt, thus the final judgment may be noted as “inconclusive”. When an independent expert is asked to evaluate seat belt usage or performance in an accident specifically or as part of the overall reconstruction effort, he usually con- siders the following elements: F E A T U R E Seat Belt Safety Assesment of Seat Belt Restraint Usage In Automobile Crashes By Jon E. Bready, Collision Safety Engineering, LC Safety