What is the basis for the 30-mph frontal-impact requirement of WC19?
The WC19 wheelchair and WTORS standards are based on existing federal safety standards for passenger vehicles. The frontal crash test is the US government’s was the first priority in occupant protection because more than half of all serious and fatal injuries occur in frontal crashes. Thus, FMVSS 208 Occupant Crash Protection requires that vehicles are barrier crash tested at 30 mph. In addition, FMVSS 213 Child Restraint Systems requires that child safety seats are sled-impact tested at 30 mph. Following the precedents set by these federal safety standards, both national and international standards for wheelchairs designed for use in transportation and WTORS have used a 30-mph crash pulse.
30 mph refers to the change in vehicle speed or “delta V” experienced by the vehicle in a crash, and not to the speed of the vehicle prior to the crash. While vehicles typically travel at speeds considerably in excess of 30 mph, a 30-mph delta-V impact test represents about a 95th-percentile crash severity in terms of real-world frontal crashes for passenger cars. That is, about 95% of real-world frontal crashes of passenger cars, minivans, and sport utility vehicles are less than 30 mph in severity. For larger vehicles, such as buses and school buses, a 30-mph frontal impact is an even less likely event. However, the test requirements of these wheelchair and WTORS standards are based on the assumption that wheelchair users will, at sometime, be seated in van-size vehicles and that most types of WTORS could be installed in smaller passenger vehicles. The standards therefore require that products be tested for this “worst-case” crash-severity situation of 30-mph, with the understanding that some, but relatively few, real-world crashes will be more severe.