ABSTRACT

1. Safety and Crashworthiness Engineering Analysis of the Ambulance Manufacturing Division’s Proposed 2007 Ambulance Standards Nadine Levick,MD,MPH1, Prof. Raphael Grzebieta BE MEngSci PhD2, EMS Safety Foundation, New York USA1, University of NSW, Sydney Australia2 ABSTRACT Objective: To analyze the safety engineering and crashworthiness validity of the AMD standards Methods: Proposed 2007 AMD standards 001-025 were analyzed by a multidisciplinary automotive safety and crashworthiness engineering and EMS team, via application of basic engineering principles of crashworthiness, published technical crashworthiness and injury mitigation literature, available crashworthiness testing data and with a focus on potential for reducing harmful loading and potential for injury causation in crashes or sudden decelerations. Results: There was no dynamic or impact crashworthiness testing required or mentioned to demonstrate safety performance at all. The testing outlined was static testing only, with no acceleration. Force = Mass x Acceleration, thus no inertial forces are described in the standard. Potential head strike zones were inaccurate, with known head strike zones specifically excluded. Anchorages for seat belts or equipment lockdowns or brackets were not required to be anchored into crashworthy structural components. There was no demonstrated patient compartment structural crashworthiness. Claims that successful testing reduced “the possibility of injuries and fatalities” … “encountered in crashes or adverse forces that can result from a vehicle impact”, were not supported by any technical data, injury criteria or thresholds and were in conflict with accepted, existing established technical science. No referenced scientific technical literature from Newton onwards. These standards were not consistent with accepted, established technical scientific approaches to vehicle safety, occupant protection or safety performance. Conclusion: Ambulance design is a vehicle and automotive safety engineering issue and is a technical field of expertise outside of standard EMS medical practice. The development of the AMD design standards appears to be well outside of accepted automotive and crashworthiness safety technical data, practice and expertise. Use of this standard has potential liability risks for manufacturers, given apparent lack of awareness of accepted vehicle crashworthiness test procedures. Industry wide standards should be developed to reflect current accepted automotive safety practice, given the current vehicle crashworthiness and occupant protection knowledge and published literature. DISCUSSION International ambulance safety standards all refer to dynamic crashworthiness tests, use of crash test dummies and reflect existing automotive safety science. These findings are unusual in that they are relevant to all involved in EMS, irrespective of whether they are the providers, administrators, medical directors, those funding the services or the insurers and the patients – few issues in EMS are so global as to embrace all these parties and for each and every EMS run. This study is believed to be the first formal independent technical automotive safety engineering review of the AMD standards by a leading independent academic crashworthiness engineer. Of interest, the AMD never responded in any way to these official and formal public comments that were submitted in response to their request for public comment and forwarded via certified mail, fax and email with written and other confirmation of their receipt. Nb. The Public Comment specific suggested technical amendments to the AMD standards, as submitted by the authors to AMD July 2007, are downloadable from: www.objectivesafety.net OBJECTIVE To analyze the safety engineering and crashworthiness validity of the AMD standards via accepted automotive safety engineering evaluation. METHODS The proposed 2007 AMD standards 001-025 were analyzed by a multidisciplinary automotive safety and crashworthiness engineering and EMS team, via application of basic engineering principles of crashworthiness, published technical crashworthiness and injury mitigation literature, available crashworthiness testing data and with a focus on potential for reducing harmful loading and potential for injury causation in crashes or sudden decelerations. Primary issues of automotive safety engineering concern were itemized. Suggested technical amendments were identified and submitted to AMD as a formal ‘public comment’ response. Medic Fatalities MedicSurvivors MedicDevastating injury Fig. 1. Catastrophic occupant outcomes in vehicle rear compartments meeting KKK/AMD specifications and standards DISCUSSION An ambulance vehicle is a vehicle that carries passengers – not just freight, and safety standards should address the real safety of those passengers (Fig 1), and reflect accepted current automotive safety science and crash test procedures. These AMD test protocols are outdated and no longer accepted in automotive safety by government regulators, manufacturers or consumer groups (ie IIHS). There is complete failure to utilize any dynamic crashworthiness test protocols and lack of meaningful or established approaches to assess injury mitigation strategies as is used routinely in automotive safety. Whilst the test protocols in the document make reference to “minimize the possibility of their failure by forces acting upon them as a result of vehicle crashes and/or sudden driving maneuvers” – these protocols are based on static tests – which in no way reflect what occurs during a vehicle crash. These are static tests claiming to demonstrate dynamic test outcomes. Such test protocols would provide misleading information that could not be supported by any current accepted automotive safety, occupant protection and crashworthiness science or any principles thereof. Static test protocols do not consider any forces generated as a result of a crash impulse, e.g. inertia forces. As is uniformly known for 400 years Newton’s 2nd law of motion states that the relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. The static test protocols in this document do not address these key injury causing forces at all. The static protocols do not take into consideration occupant kinematic movement and hence possible potentially injurious contact points at highly localized points such as sharp corners, etc. Thus these protocols do not in any way reflect meaningful or accepted safety tests for occupant protection LIMITATIONS This analysis was a brief analytical technical report, and does not in any way address any specific vehicle, but rather addresses the broad issue of the safety of the design standards CONCLUSION Ambulance design is a vehicle and automotive safety engineering issue and is a technical field of expertise outside of standard EMS medical practice. These AMD ambulance design standards for the design of the ambulance vehicles, and their development, are outside of accepted automotive and crashworthiness safety technical data, practice and expertise and not consistent with accepted, established technical scientific approaches to vehicle safety, occupant protection or safety performance. Use of this standard has potential liability risks for manufacturers, given apparent lack of awareness of accepted vehicle crashworthiness test procedures. Industry wide standards should be developed to comprehensively reflect current accepted automotive safety practice, given the current vehicle crashworthiness and occupant protection knowledge and published literature. BACKGROUND USA ambulances are built by aftermarket ambulance retrofitter/ manufacturers, members of the Ambulance Manufacturing Division (AMD) of the National Truck Equipment Association. The AMD is an organization that is essentially outside of the automotive safety industry oversight. The rear occupant compartment of the box/chassis ambulance (Types I and III) is an aftermarket occupant/passenger structure designed and built by the retrofitter/manufacturer to meet AMD’s own design standards. Similarly, for the design of the Type II vehicle retrofit modifications. The automotive safety and crashworthiness industry has no technical oversight over the development of AMD standards. RESULTS • There was no dynamic or impact crashworthiness testing required or mentioned to demonstrate safety performance of the rear occupant compartment of the ambulance at all. • The testing outlined was static testing only, with no acceleration (aside from gravity alone). Force = Mass x Acceleration, thus no inertial forces are described in the standard. • Potential head strike zones were inaccurate, with known head strike zones (such as the interior walls of the rear compartment) specifically excluded. Anchorages for seat belts or equipment lockdowns or brackets were not required to be anchored into crashworthy structural components. There was no demonstrated patient compartment structural crashworthiness. • Claims that successful AMD testing as specified in this AMD standard, reduced “the possibility of injuries and fatalities ..… encountered in crashes or adverse forces that can result from a vehicle impact”, were not supported by any technical data, injury criteria or thresholds and were in conflict with accepted, existing established technical science. • There was no referenced scientific technical literature from Newton onwards that pertained to crashworthiness. References to existing Federal Motor Vehicle Safety Standards (FMVSS), were to standards for which there were formal and specific exemptions for the rear compartment of the ambulance. • There was a complete absence of any real world injury data applied to the determination of these test protocols. • There was a complete failure to utilize any test protocols that include injury criteria that currently exist for automotive safety testing (such as HIC, neck injury loads, chest decelerations, femur loading etc) government regulated or otherwise. • Lack of reference to current accepted and routine passive structural crashworthiness and occupant protection technologies, such as crumple zones, automotive grade seating in all seating positions, seat belt pre-tensioners, automotive grade padding and other safety technologies. RESULTS (contd) • Test protocols described in this document are not in any way supported by any evidence or referenced scientific or automotive safety literature. The static test procedure in the document spreads loads over a large area and thus DO NOT reflect real world impact forces that are dynamic and usually localized to a small area and of a much higher magnitude than a static self weight load can generate. Contact: Nadine Levick MD, MPH - nlevick@attglobal.net