Independent Automotive Forensic Engineering Expert, Belgrade, Serbia ..... Product defects include mechanical, electrical or energy supply failures that affect ...
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FORENSIC EVIDENCE IN ROAD ACCIDENTS CAUSED BY VEHICLE’S MECHANICAL FAILURES Prof. Dr. Čedomir Duboka Independent Automotive Forensic Engineering Expert, Belgrade, Serbia
ABSTRACT We now have over one billion road vehicles on the planet. In more than 60 million road accidents per year involving casualties, about 1,25 million people dies, 76% of whom are men and boys. Road traffic injuries make app. 2,2% of the total number of death worldwide, being a leading cause of mortality for many years, though most traffic crashes are both predictable and preventable. The situation is worst in lowincome countries, with rates more than double as those in high-income countries, why there are a disproportionate number of deaths relative to the (lower) level of motorization. There are numerous causes of road accidents (like speeding, distracted driving, drunk driving, reckless driving, rain, running red light, running stop lights, teenage drivers, night driving, design and other technical defects, unsafe lane changes, wrong-way driving, improper turns, tailgating, driving under the influence of drugs, ice, snow, road rage, potholes, drowsy driving, fog, deadly curves, tire blows, animal crossing, street racing, etc.). Different information deals with the technical cause of road accidents, with special emphasis to vehicle failure, showing that in between app. 2 – 15% cases this was the main cause of an accident. Forensic engineer, or court expert witness, is occasionally requested to confirm or deny the claim that given road accident happened because driver faced loosing vehicle motion control due to mechanical failure occurring immediately before vehicle reached the point of impact (POI). There are even cases that (a) claimed failure was not registered or documented by the police crew reviewing the accident site, (b) no evidence of the failed vehicle part was provided to the court expert, (c) no forensic or any other technical inspection of the damaged vehicle was performed after the accident occurred, and (d) the said damaged vehicle has been sold to unknown customer or was recycled before being examined by the forensic engineer. In this paper the challenge for the forensic engineer is explained in looking for the way out from this situation by application of systems engineering principles while analyzing all evidence available, including accident scene drawings and photos, oral and/or written information, statements, and all other sources.
KEYWORDS: Automotive forensic engineering, Systems engineering, Vehicle mechanical failure analyses
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Introduction
Road traffic injuries make app. 2,2% of the total number of death worldwide, being a leading cause of mortality for many years. There are numerous causes for road accidents to occur (like speeding, distracted driving, drunk driving, reckless driving, rain, running red light, running stop lights, teenage drivers, night driving, design and other technical defects, unsafe lane changes, wrong-way driving, improper turns, tailgating, driving under the influence of drugs, ice, snow, road rage, potholes, drowsy driving, fog, deadly curves, tire blows, animal crossing, street racing, etc.). In depth studies suggest that vehicle factors, particularly defects, are "causal, possibly causal or contributory" in about 2 to 28% of all road accidents, while some statistical data show that more than 80% of traffic accidents find their root cause in a driver failure, who is the main accident’s player (Ledon, 2009). In statistical reviews of road traffic accidents more and more attention is paid to so called “Distracted Driving” which may be resulting from different influencing factors like use of mobile phones, and similar. This may be the “fertile ground” for undertaking preventive measures by which number of accidents might be reduced. In the case of accident analyses and reconstruction this is a “fuzzy” or “blured” area because such issues (a) are not of the technical nature, and (b) it is almost impossible to identify and confirm such driver’s behaviour by means of any technical (forensic) evidence. As such, it is important to describe driver’s behavior during all phases of the accident, as a function of time, like:
His sight (from the opposite vehicle, from the pedestrian...), His interpretations from the situation (Hazard and risk assessment, ...), His decisions in the midst of the action (swerving manoeuvres, acceleration or braking ...), His actions (swerve speed, full brake with wheels blocked...), etc.
The number of road traffic accidents in which vehicle’s physical defects or deficiencies were contributory factors or more directly causative, is assumed to be proportional to the number of defective vehicles on the road present at any time - almost 50 percent following Autofore (2007), Dekra (2008 and 2009) and AMSS CMV (2011). Following the Oxford Dictionary (2017) Road Traffic Accident is “An unfortunate incident that happens unexpectedly and unintentionally, typically resulting in damage or injury” or “A crash involving road or other vehicles, typically one that causes serious damage or injury”. Even better, the Concise Oxford Dictionary says that “Accident” is: (a) An event which is without apparent cause or is unexpected, (b) An unfortunate event causing physical harm or damage brought about unintentionally or (c) The occurrence of things by chance. These definitions don’t say, but demonstrate that Road Traffic Accident Analyses and Reconstruction means “trying to find solution to a puzzle” (or “problem”) in which all different pieces should be put together in a logical way in order to arrive at the correct solution of seriously arising mathematical or logistical problems, based upon inquiry and discovery, where good deduction skills are requested being improved with practice, Wikipedia (2017). It is seldom found that a single factor was responsible for a collision, but for many there is an explicit desire to isolate a sole cause. More often than not a series of events existed simultaneously to produce the unfortunate result, as explained in Collision Analyses (2017), where more sophisticated definition of an accident is offered: ”A rare random multi factor event in which one or more road users failed to cope with their environment.” However, it is still mostly the case that consumers of automotive forensic engineering services (courts, lawyers, insurances, even some “experts”), most probably due to inappropriate education in this field, and lack of their own knowledge and experience, consider mechanical engineers being magicians, who only should use their magic wand to immediately and strictly point out only one and single cause of the road accidents. This particularly applies to the cases where so called “technical factor” is called of being responsible.
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But the truth is quit opposite - in automotive technology nothing can be only “black” or only “white”. Just to mention that modern motor vehicles are highly sophisticated and complex repairable technical systems usually composed of few thousand components, whose (technical) condition is subject to continuous degradation due numerous reason, Duboka (1992). All vehicle parts are normally subject to failures and/or malfunction. All accident analyses and reconstruction problems should be considered within the whole their complexity, with serious validation of certainty, i.e. reliability. In practice, there is significantly much more road accident cases in which high uncertainty is present when compared to the cases in which there exists “enough physical and other evidences” by the use of which it would be possible with no doubts to explain how (and why) certain events occur. Road traffic injuries have been a leading cause of mortality for many years, though most traffic crashes are both predictable and preventable. Green Cars Reports (2017) says that we now have over one billion road vehicles on the planet. In more than 60 - 100 million road accidents per year involving casualties, the number of road traffic deaths – 1.25 million in 2013, out of which 76% of whom are men and boys – has remained fairly constant since 2007, despite the increase in global motorization and population. The situation is worst in low-income countries, where rates are more than double than those in high-income countries and there are a disproportionate number of deaths relative to the (lower) level of motorization (WHO, 2015).
Figure 1 Main causes for all road users
Figure 2. Main causes for road vehicle accidents
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Therefore, the job of the automotive forensic engineer comprises a combination of science, experience, and some art by using the laws of physics, mathematics, engineering, etc. mixed with the expert’s real-world automotive component background, expertise and experience in the design, testing, development, manufacturing and maintenance.
Figure 3. Vehicle Condition as Crash Associated Factor This comprises the systematical analyses of failed automotive components in the pursuit of and the identification of the cause(s) or root cause(s) of the physical damage or other disablement done to vehicle by collision. All details that compose the puzzle must be identified, and well positioned with respect to their interaction with (all) others in order to enable the “whole picture” to be made. In particular, forensic engineer, or court expert witness, is occasionally requested to confirm or deny the complaint usually made by the driver of the bullet vehicle that given road accident happened after driver lost control over the vehicle in motion due to mechanical failure occurred immediately before this vehicle reached the point of impact (POI). The worst cases are those in which the uncertainty is very high due to the fact that almost no (physical) evidence exists in such cases, like: (a) reported vehicle failure was not recorded or documented by the police report from the accident site, (b) no physical evidence of the failed vehicle part was presented to the court expert, (c) no forensic or any other technical inspection of the damaged vehicle was performed after the accident occurred, (d) the said damaged vehicle has been sold to unknown customer or was recycled before being examined by the forensic engineer, and . (e) accident happened long time before the court expert was asked for his/her oppinion. The purpose of this paper is to challenge automotive forensic engineers to commence applying an advanced examination approach based on the application of systems engineering principles while analyzing all evidence available, including accident scene drawings and photos, oral and/or written information and/or statements, as well as all other sources. There should be no any doubts that each road accident is composed of many mutually interactive details and influencing factors which are specifically characterizing the given case, while the way of how these details are composed apply only to this and not to any other accident.
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This paper offers a systematic approach to forensic engineering investigation applied in the postcollision condition of automotive braking, steering & suspension, wheels & tires. As already mentioned, such approach rely on the hypothesis that each road vehicle accident should be considered representing a “puzzle” (Wikipedia, 2017), consisting of in advance unknown but for certain large number of elements. Only after this puzzle was fully assembled the accident case may be considered fully solved.
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Examples of complaints that vehicle mechanical failure caused an accident
Motor vehicles are extremely dangerous general purpose consumer goods, subject to different kind of failures, including those related to road accidents, and resulting both in human casualties but also in vehicle and infrastructure damages. Following Collision Analyses (2012) in the years since its inception, the motor car has become the single greatest contributor of accidents. Catastrophic vehicle defects designate the condition of sudden and unexpected loss of control over vehicle in motion by the driver due to partial or total loss of control over a given vehicle motion control system – braking or steering. Vehicle structure is very complex so that catastrophic defect of the vehicle as a whole may also result from partial defects of some of its sub-systems, or even only single components. Automotive wheel systems are often blamed for causing accidents, but their complete and catastrophic failure is rare (less than 0,2% of all cases). Automotive forensic experts are asked to determine the most likely events that led up to and caused the given product to fail. These findings are often asked to fulfill specific time and cost constrains. An examination of the involved vehicles needs to be undertaken in order to establish whether there could have been any mechanical defect or other kind and type of component failure which may be connected to accident causation (Collision Analyses, 2012). Some typical examples are presented earlier, (Duboka, 2007; Duboka et al., 2009; Muždeka, Grkić and Duboka, 2011; Duboka, 2011; Duboka, 2012a; Duboka, 2012b), as illustrated in Figures 4 and 5, while a couple of new cases is shown in the present paper. 2.1. New case #1 While travelling in the night through the right-hand curved dry road section separated in two opposite direction road lanes by means of the double full centre road line car “A” (BMW) passes to the opposite (left) road line where it collides with the car “B” (Volvo) travelling in the appropriate road lane and opposite direction. Left hand front side body sections were damaged on both cars, as documented by the police. No forensic or other technical inspection of the damaged vehicles was performed afterwards. No physical evidence of any failed part of the car “A” was registered or documented by the police team reporting from the accident site or presented to the court expert. Driver of the car “A” (who was under the influence of alcohol) states that “while driving he feels something suddenly breaks down at the front left side of his car; the car was pulled to the left; he lost control over it”, while “the mechanic who repaired this car said the left-hand side steering arm (tie rod or knuckle arm) was broken”. 2.1. New case #2 While in the daylight leaving the left-hand curve closing the “S” curved dry road section, vehicle “A” (VW van) passes to the opposite (left) road lane crossing both interrupted center road line for vehicles travelling in his direction and full centre road line for vehicles travelling in the opposite direction. Near the edge of the opposite road line it collides with the car “B” (FIAT Seicento) travelling in his road lane and opposite direction. Car “B” was heavily damaged. Van ”B” rests on his roof app. 50 meters after the point of impact. A number of traces were recorded by the police, including the fact that front left wheel of the car “B” was found separated from the vehicle. No forensic examination of vehicles was done. Extraordinary technical inspection as ordered by the police was performed only by visual inspection (regular procedure was not possible to be applied due to the extent and nature of damages) showing that (aside from the NMV17SAF13 - 5 / 10
vehicle body damages) there were damages of the front left side of the running gear of van – damaged front left section of the vehicle frame and front left shock absorber, front left wheel rim deformed, front left tire out of pressure, and left lower control arm separated from the chassis and pulled backwards. Are all these damages mutually inter-related, and in which order they occurred? Driver of the van (who was under the influence of alcohol) stated that “while driving through the right-hand section of the “S” curved road his field of vision was obstructed; even then, and in particular while entering the left-hand section of the “S” curved road, his vehicle was pulled-out to the left; he heard noise like something breaks-down, but does not know was it in the wheel or steering, cannot say that something was wrong with the steering wheel, or transmission, or pedal controls; he tried to drive the van back to the appropriate road lane, but there was no enough time nor enough space to do so; therefore, it was not possible for him to avoid colliding with this car”.
Figure 4. Did tire failure cause these accidents with severe vehicle damage and fatalities?
Figure 5. Did wheel system cause this accident with severe vehicle damage and fatalities?
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3.
The character of mechanical failures in motor vehicles
A complete catastrophic automotive system failure is an extremely rare event, but a design flaw and/or product failure, maintenance or repair workmanship failure or component break-down may be the most significant contributing factor in the incident and related personal injuries causation. Product defects include mechanical, electrical or energy supply failures that affect control systems of the vehicle (such as throttle, brakes, steering, or suspension including wheel and tire failures), and flaws in the design or performance of the occupant protection systems (like seat belts or air bags). In every road vehicle accident analysis, potential product defects, vehicle deficiencies and malfunction or other vehicle related factors should be thoroughly investigated and considered from the causation point of view – is a given vehicle defect identified during on site vehicle condition inspection only a consequence of the impact or it might be alone and /or associated with the other potential accident causes? In addition to a very specific à posteriori examination of causes and consequences of the post collision automotive component(s) physical damage(s) developed before, during and/or after a road accident took place, automotive forensic examination is somewhat of traditional standardized (mechanical) engineering procedures applied to design and development process in association with the automotive maintenance technology and vehicle value estimation analyses. That is how it complies more with the inverse engineering and practice – starting from the consequences of an accident forensic investigator is asked to define its causes. However, even in this way forensic engineer will never reach his conclusion with enough high certainty of, let us say 99,99%. In order to reach certainty to be as high as possible something else should be done – the complex view of the event should be created. Not only purely mechanical analyses should take place in this, but also all other relevant details concerning pre-crash, collision itself and post-crash phase of the accident should be simultaneously taken into consideration, because none of these aspects can be processed separately due to numerous interacting relation connecting all of them in one single event. One should always bear in mind that every road traffic accident happens in the complex interaction of factors related to the driver, vehicle and the environment. Therefore, mechanical deficiencies and/or failures of vehicles involved in an accident do not occur just like that and are developed while vehicle is driven by his driver, was travelling on the given road under given road and environment conditions, etc. Therefore, as long as a vehicle is travelling on the road there is a firm interaction (contact) of (at least) his wheels with the road surface, as said by Dr. Edmond Locard in his exchange principle that “Every contact leaves a trace”, Wikipedia (2017a). In particular, it should be emphasized that accident are the resulting event from a number of single events and behaviours that are happening during the pre-crash phase, involving all parties – vehicle, driver and environment. Clear identification of pre-crash behaviours of all involved parties including vehicle while following desired trajectories are crucial to understand how these parties were approaching the point of impact, and to afterwards analyze why collision happened. In addition to that the Time-Distance analyses is also extremely important to be done as precisely as possible. Apart from this, would it be important for an automotive forensic engineer who has the task to analyze mechanical failures of a vehicle to know more about involved vehicle usage pattern, its maintenance history, its age and real technical condition, etc.? These issues are so “blured” that often are more or less fully neglected. Does it mean these things are not important from the prospective of their impact to an accident? Such a conclusion would be completely wrong from the purely mechanical point of view, as one may learn from Duboka (1992, 1999), but the real life says the opposite. Engineering investigators in a Product Liability or Failure Analysis Cases are almost always faced with the following questions: Did any vehicle system defect caused loss of the driver control and/or
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contribute to a given fatal road accident? If so, what specific mechanism failed, and why? Was this system poorly designed, was there a manufacturing problem, improper maintenance, or what? (Duboka, 2012) The investigator is supposed to bring its expert's conclusions based on scientific methodology. Because motor vehicles are among the most complex systems today, the knowledge of an automotive forensic investigator should include excellent understanding of the vehicle design, the way of operation of specific vehicle kind and category in addition to detailed knowledge about potential failure modes and related causation factors. Therefore, appreciation of the vehicle fault analyses, including Fault Tree Analyses and Failure Mode and Effect (or Effect and Criticality) Analyses would be essential to enable forensic investigator to performed quality vehicle damage analyses. Engineering failure analysis has two major objectives (MEE, 2009): - to determine the failure mechanism - the basic material behavior that resulted in the failure, and - to determine the failure root cause - the fundamental condition or event that caused a failure, like design deficiencies, manufacturing errors, improper material, material defects, inadequate maintenance, abusive service, etc. Catastrophic vehicle defects (Duboka, 2012) designate the condition of sudden and unexpected loss of control over vehicle motion by the driver when he loose partially or totally the control over a given vehicle motion control system – braking or steering. Catastrophic defect of the vehicle as a whole may result from partial defects of some of vehicle sub-systems, due to their complex structure. Losing control over braking means the driver would not be capable to control the vehicle deceleration, while losing control over steering may occur in the case of catastrophic defects in tire(s) and/or steering and suspension vehicle systems, while vehicle directional instability may also be caused by inappropriate brake balance. Partial failures are vehicle deficiencies contributing to vehicle performance realization. Statistics say that at least 50% of vehicles in traffic may be considered defective, meaning some kind of partial failure was taking place. It is not possible to rate catastrophic versus partial failures. However, professional logics is leading to the conclusion that very large majority of these deficiencies do not have implicit catastrophic character, but this does not mean that such deficiencies will never became causative factor of accidents. On the contrary, it is very probable that lasting vehicle deficiencies when neglected by the driver may become important causative factor for road accidents in which technical factor is contributing independently or in conjunction with another causative factor, like human errors, etc. While identifying partial vehicle failures (or deficiencies) as the cause of road accidents the fact is that such deficiencies are very often hard to discover afterwards, i.e. after an accident developed, particularly with vehicles with which performance evaluation remains impossible in the postcollision condition of a vehicle. Very often, and particularly in the case of heavy road accident with vehicles subject to massive (physical) damage pre-collision existence of partial vehicle failures remains hidden and may never be allocated.
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Conclusion
Automotive forensic investigation represents very complex task. Modern road vehicles are among the most complex systems today. In addition to that, modern motor vehicles are extremely dangerous general purpose goods. Motor vehicles are maintainable technical systems, where occurrence of faults/failures/deficiencies or defects is imminent. Due to (a) technical reasons related to the vehicle, (b) human reasons due to the vehicle driver or other humans that are taking part in the road traffic and (c) some other, like environmental conditions, some of these deficiencies often produce tragic consequences, like material destruction, human injuries and fatalities, known under the common name as “catastrophic vehicle physical damages”.
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The crown question to which an automotive forensic examination should offer the answer would be “Is the given automotive product physical damage done to vehicle by collision being the cause or the consequence of an accident?” That is why this paper offers the systems engineering principles based approach to forensic engineering answering to the question “Was the physical damage of an automotive element/sub-system/system the cause or the consequence of a given road accident?” This approach relies on the fact that it is seldom found that a single factor was responsible for a road vehicle collision. The Road Traffic Accident Analyses and Reconstruction in fact try “to find solution to a puzzle” (or “problem”) in which all different pieces should be put together in a logical way in order to arrive at the correct solution of arising problems, based upon inquiry and discovery. Automotive forensic investigators are asked to provide highly professional expertise of such events to legal or other authorities. In order to be capable to do that at the best of their knowledge this knowledge should be a successful combination of general and specific technical knowledge in association with some other personal and professional performance and skills. An excellent knowledge of the automotive vehicle technology, including failure mode analyses is essential for an automotive forensic investigator to fulfill his task successfully. This is particularly the case of forensic investigation of vehicle wheel systems – braking, steering, suspension, wheels and tires.
Reference AMSS CMV (2011), Vehicle without failure – Safe Vehicle (In Serbian). Automotive Club of Serbia with the Traffic Police of the Republic of Serbia, Available at www.amss.org.rs (Last Accessed 18 Feb 2017). Autofore (2007), Study on the Future Options for Roadworthiness Enforcement in the European Union [online], Available at http://citainsp.org/studies/autofore-2007/ (Last Accessed 16 Feb 2017) Collision Analyses (2012), Collision Analyses, [online] Available at http://collisionanalysis.co.uk/ introduction.htm (Last Accessed 18 February 2017). DEKRA (2008). Road Safety Report 2008, [online] Available at http://www.dekra.de/c/document_ library/get_file?uuid=05eaaed6-77cd-4ece-8607-7a9e34b99f63&groupId=10100 (Last Accessed 18 Feb 2017). DEKRA (2009). Road Safety Report HGV 2009, [online] Available at http://www.dekra.de/c/ document_library/get_file?uuid=93794ebd-d9c9-488d-bdd3-bdca44e8a98f&groupId=10100 (Last Accessed 18 Feb 2017). Duboka, Č. (1992), Automotive Maintenance Technologies (in Serbian), Faculty of Mechanical Engineering, Belgrade, ISBN 86-7083-211-9 Duboka, Č. (1999), Autoservices (in Serbian), JUMV, Belgrade, ISBN 86-80941-24-7 Duboka, Č. (2007), Automotive Forensic Engineering – 2007 Status in Serbia, Paper NMV0718 presented at the XXI JUMV International Automotive Conference 2007, Belgrade, Serbia Duboka, Č., Filipović, Ž., Gordić, M., Došlić, M. (2009) Second hand vehicle maintenance frauds, Paper NMV0912 presented at the XXII JUMV International Automotive Conference 2009, Belgrade, Serbia Duboka, Č. (2010) Vehicle Condition Based Roadworthiness Performance Indicator, Paper F2010H023 : CD Proceedings, FISITA World Automotive Congress, Budapest, Hungary Duboka, Č. (2011) Braking and Running Gear Failures – Cause or Consequence of road accident? (in Serbian), LAFI Seminar S4, Faculty of Mechanical Engineering, Belgrade, Serbia, Duboka, Č. (2012) Considerations in forensic examination of automotive systems, Int. J. Forensic Engineering, Vol. 1, No. 2 Green Cars Reports, [online] Available at http://www.greencarreports.com/news/1093560_1-2billion-vehicles-on-worlds-roads-now-2-billion-by-2035-report (Last Accessed 18 Feb 2017). Ledon, C. (2009) Driver Behavior – Human Factor [online] Available at http://www.expertaccidentologie.fr/driver.html (Last Accessed 18 Feb 2017). MEE (2009) [online] Available at http://mee-inc.com (Last Accessed 08 March 2012).
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Oxford Dictionary (2017) [online] Available at https://en.oxforddictionaries.com/definition/us/ accident (Last Accessed 18 Feb 2017) Wikipedia (2017) [online] Available at https://en.wikipedia.org/wiki/Puzzle (Last Accessed 18 Feb 2017). Wikipedia (2017a) [online] Available at https://en.wikipedia.org/wiki/ Locard's_exchange_principle (Last Accessed 18 Feb 2017). WHO (2015): Global Status Report on Road Safety, [online] Available at www.who.int (Last Accessed 18 Feb 2017).
Biographical note Dr. Čedomir Duboka is Full Professor (ret.) of Automotive Engineering at the University of Belgrade, Faculty of Mechanical Engineering, formerly Head of Laboratories for automotive forensic engineering, braking and friction mechanisms, President of JUMV – Society of automotive engineers in Serbia, CEO of EVU CG Serbia, organizer of International automotive conferences “Science & Motor Vehicles”, author/co-author of more than 25 Monographs and/or their parts, books and/or textbooks, 120 papers presented at international congresses and national / international conferences, 45 papers published in international / national journals. He acts in the field of Automotive Engineering, with particular emphasis on braking and forensic engineering.
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