ollision C
Volume 16 Issue 2
The International Compendium for Crash Research
Crash Data & Images Available After Automotive Repair with Airbag Control Module Replacement
Crashology Impact Severity
CRASHCON22
Live Crash Testing
The Lost Energy
of Planar Impact Mechanics
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Contents
Volume 16 Issue 2
inside 3
Content Information
4
Letter from the Editor
5
Collision Magazine Info and Advertiser Index
12
features 6
Crash·ol·o·gy - Impact Severity: A function of vehicle closing speed or vehicle impact speed (ground speed)? by Wesley Vandiver, Robert Anderson, Michelle Hoffman, David Hallman, Billy Cox
12
50
CRASHCON22: The Value of In-Person Conferences and Live Crash Testing by Billy Cox and Robert Anderson
38
Vehicles, VIN's, Certification Labels, and parts What “Model Year” is it?? by Daniel W. Vomhof III
46
My Turn At The Wheel: What Is "30" How And Why Should We Use It?
66
by Richard C. Rinker
50
Nissan Automobile EDR Recording Characteristics by David M. Hallman, Billy S. Cox, Jr., Robert D. Anderson
66
The Lost Energy of Planar Impact Mechanics
82
Utilizing EDR Data To Determine The Effects Of Hard Braking On Delta-V Calculations In Low-To-Moderate Speed Impacts
by Micky Marine
92
by Shannon Crowley, Camila Marrero Torres, Alex Kazmierczak, Christopher J. Furbish and Bryan Randles and Justin Brink
92
Crash Data and Images Available After Automotive Repair with Airbag Control Module Replacement by Robert Anderson www.collisionpublishing.com
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crash·ol·o·gy THE SCIENCE OF CRASHES Wesley Vandiver
Robert Anderson
Collision Forensics
Michelle Hoffman Forensic Injury Analysis
Biomechanics Analysis
David Hallman Hallman Engineering
Billy Cox
Billy Cox Group
Impact Severity: A function of vehicle closing speed or vehicle impact speed (ground speed)?
A
persistent misconception in vehicle crash analyses is that collision severity and injury potential are related to a vehicle’s ground speed at impact rather than to its closing speed and the Delta V experienced. That is, claims are often made that if a struck vehicle has a higher impact speed (over-the-ground speed) at impact, this inherently means that it experiences a more severe impact. Actually, impact severity is related to a vehicle’s change in velocity (Delta V) during the impact, which is a function of its closing speed, which may or may not be equal to its impact speed (ground speed). This misconception was described by Schmidt, et al., (1998), who surveyed practicing reconstructionists at a crash conference and received several different misconceived explanations from the respondents with widely varying backgrounds, education and training. [1] Schmidt, et al., found that the given reasons for this misconception varied, but two reasons predominated, “the absolute energy notion” and the “absolute momentum notion” (Schmidt, 1998). A theoretical analysis of the fundamental physics as to why these two notions are incorrect can be found in the paper by Schmidt, et al. An example of this misconception would be the thinking that during a vehicle-to-vehicle rear-end impact: if the struck vehicle is traveling at some speed, rather than stationary at impact, then it somehow experiences a more severe impact. That is, if Vehicle A was traveling 20 mph and was struck from behind by Vehicle B traveling 30 mph (closing speed of 10 mph), some have the misconception
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that this impact would be more severe than if Vehicle A was stationary and struck by Vehicle B traveling 10 mph (closing speed of 10 mph). An analogy to demonstrate this principle follows. Person A is on a jet airplane that is flying at 400 mph relative to the earth’s surface. They walk down the aisle of the airplane at 2 mph and accidentally bump into Person B, who is standing in the aisle of the airplane. Relative to the earth’s surface, Person A is traveling 402 mph and Person B is traveling 400 mph. Is this impact more severe for either party than if Person B was standing on the earth’s surface and Person A walked into him/her at 2 mph? The answer is no. The severity is the same in both scenarios, because it is the speed of the people relative to each other, not their speed relative to the earth’s surface that is important. This principle was also demonstrated with crash testing conducted at the 2022 SATAI Crash Conference. A series of two tests were performed. In Test 1, a 2007 Chevrolet Impala (silver) was traveling 34 mph when it impacted the back of a 2006 Chevrolet Impala (white) that was traveling 21 mph. In Test 2, the 2007 Impala was stationary when it was struck from behind by the 2006 Impala that was traveling 13 mph. Thus, even though the bullet vehicle was traveling 34 mph in Test 1 and only 13 mph in Test 2, the closing speed in both tests was 13 mph. Both vehicles were instrumented with accelerometers. In addition to the accelerations and Delta Vs of each vehicle, impact speeds were measured using Racelogic VBOX
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Impact Speed mph TEST 1 BULLET - 2007 silver Impala (vehicle #4) TARGET - 2006 white Impala (vehicle #3) TEST 2 BULLET - 2006 white Impala (vehicle #3) TARGET - 2007 silver Impala (vehicle #4)
Closing Speed mph 13
Delta V mph
34 21
-7.8 7.7 13
13 0
-10 7.6
Table 1: Vehicle ground speeds, closing speeds and Delta Vs for Tests 1 and 2. equipment. As seen in Table 1, the impact speed relative to the ground for the bullet vehicle was 34 mph in Test 1 and 13 mph in Test 2, yet the closing velocity between the vehicles was 13 mph in each test. It is also clear from Table 1 that the Delta V experienced by the target vehicle in Test 1 (7.7 mph) was equal to the Delta V experienced by the target vehicle in Test 2 (7.6 mph). The bullet vehicle’s Delta V in Test 2 (-10mph) was 2.2 mph greater than the bullet vehicle’s Delta V in Test 1 (-7.8 mph). This is attributed to braking of the bullet vehicle during impact in Test 2. As discussed in the previous Crashology article, “Event Data Recorder Delta V: The Effect of Tire Friction,” bullet vehicle braking can inflate the measured Delta V of the bullet vehicle. [2] Figure 2 shows the Delta Vs of the bullet vehicles for Tests 1 and 2.
BULLET – Driver TARGET – Driver
Age Years 62 55
Still images from video of the vehicles at maximum engagement during impact for Test 1 and Test 2 are shown below in Figures 3 and 4, respectively. These still images demonstrate that the dynamic crush of the bullet vehicle at maximum engagement is very similar. The bullet vehicle demonstrates slightly more dynamic deflection of the lower bumper cover during Test 2 than in Test 1; however, there was no noticeable difference in the static residual deformation after the collisions. A single human volunteer served as the driver of the target vehicle in each test, while a second human volunteer served as the driver of the bullet vehicle for each test. The magnitude of the impacts was controlled to be within the established tolerable range for volunteers. Information on the volunteers is shown below in Table 2.
Gender M M
Height Inches 73 67
Sitting Height Inches 36 36
Weight Pounds 230 200
Table 2: Information on human volunteer drivers. Peak Head Accel Peak Thorax Accel Peak Lumbar Accel Shoulder Belt Load Lap Belt Load g's g's g's lbsf lbfs TEST 1 BULLET - Driver TARGET - Driver TEST 2 BULLET - Driver TARGET - Driver
4.8 9.0
6.0 7.1
8.9 5.4
275.5 87.4
29.2
6.3 11.6
8.3 9.3
8.5 6.9
319.4 84.1
34.7
Table 3: Volunteer driver experienced accelerations and seat belt loads. www.collisionpublishing.com
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CRASHCON22:
The Value of In-Person Conferences and Live Billy S. Cox, Jr Crash Testing Billy Cox Group
I
f you’re like me, you are tired of the “Covid Emergency” that radically changed our travel habits and the way we did business over the last couple of years. Shortly after the close of the EDR Summit in Houston in March of 2020, the world shut down. Perhaps the most obvious casualty was the in-person conference. While there have been a few in-person conferences with crash testing, i.e. SCARS 2021 and 2022 held in July in Charleston, SC, MATAI 2021 held in Des Moines, IA and SATAI 2022 held in Glendale, AZ in January 2022, they haven’t necessarily been well-attended. Finally, we may have turned the corner on the moratorium on in-person training. One of the most obvious recent examples occurred in May 2022. The Barczyk Biomechanics Institute organized CrashCon22 in New Orleans, Louisiana that was attended by up to 150 people from a variety of professions. About two-thirds of the attendees represented the Reconstructionist and Biomechanists private sector and law enforcement communities and about one-third were members of the chiropractic community. The stated purpose of the conference was to “Help determine injury mechanism to scientifically support an objective causation opinion” and “understanding the injury mechanism and human tissue response.”
Robert “Bob” Anderson Biomechanics Analysis
chael Rosenfield and Daniel Vomhoff III, performed a series of twelve crash tests, with the first one going off at about 9:00 a.m. and the last at about 3:15 p.m. The test series made up ten low-speed tests with human volunteers, plus two remote driven high speed tests. We also utilized two Anthropomorphic Test Devices (ATDs) in eleven of the tests. Overall, more than 70 channels of data were collected in each two vehicle collisions. More than 750 data channels were collected in 12 total tests. There were up to 12 video camera angles, plus drone video for each test and up to 70 photograph images.
This conference organizer David J. Barczyk, D.C., a practicing Louisiana chiropractor for 20 years. Dr. Barczyk has the distinction of being the only treating doctor in Louisiana that has been qualified to testify as an expert in motor vehicle crash biomechanics. While his training is somewhat novel, there is a trend for chiropractic practitioners to seek and obtain training in crash reconstruction.
Crash testing occurred on Friday. The team compiled all of the data on Saturday and presented the data to the attendees on Sunday before the close of the conference. Because of the short turnaround between testing and presentation and the volume of data collected, conference attendees were provided with a DropBox link to all processed data about seven days after the conference concluded.
The crash team consisting of Robert (Bob) Anderson, Christopher Furbish, David Hallman, Bryan Randles, Mi-
The vehicles we acquired to perform the tests are as follows:
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V1: 2007 Chevrolet Suburban, VIN# 3GNFC16JX7G305199 (EDR Support, D2M Cable 02003320 with Hitch). Weight as tested, 5580 lbs, plus occupant if applicable.
V2: 2004 Chevrolet Suburban, VIN# 3GNEC16Z04G135478 (EDR Support, D2M Cable 02003003, NO Hitch). Weight as tested, 5350 lbs, plus occupant if applicable.
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References 1.
2.
Szabo TJ and Welcher JB, “Human Subject Kinematics and Electromyographic Activity During Low Speed Rear Impacts,” SAE paper 962432, Proceedings of the 40th Stapp Car Crash Conference, Albuquerque, NM, November 1996. Szabo TJ, Welcher JB, Anderson RD, Rice MM, Ward JA, Paulo LR and Carpenter NJ, “Human Occupant Kinematic Response to Low Speed Rear-end Impacts,” SAE paper 940532, in Occupant Containment and Methods of Assessing Occupant Protection in the Crash Environment (SP-1045), Society of Automotive Engineers, Inc., Warrendale, PA, 1994.
12. West DH, Gough JP and Harper GTK, “Low Speed Rearend Collision Testing Using Human Subjects,” Accident Reconstruction Journal, May/June 1993. 13. Meyer S, Weber M, Castro W, Schilgen M and Peuker C, “The Minimal Collision Velocity for Whiplash,” in Whiplash Injuries: Current Concepts in Prevention, Diagnosis and Treatment of Cervical Whiplash Syndrome, Robert Gunzberg and Marek Szpalski, ed., Lippencott-Raven, Philadelphia, 1998. 14. Zaborowski AV, "Human Tolerance to Lateral Impact with Lap Belt Only," SAE Number 640843, Proceedings of the 8th Stapp Car Crash and Field Demonstration Conference, October 1964.
3.
Szabo TJ and Welcher JB, “Human Subject Responses to Various Acceleration Fields,” Presented at the Low Speed Collision TOPTEC”, Society of Automotive Engineers, Vancouver, BC, August 1996.
15. Zaborowski AV, "Lateral Impact Studies - Lap Belt Shoulder Harness Investigations," SAE Number 650955, Proceedings of the 9th Stapp Car Crash and Field Demonstration Conference, 1965.
4.
Mills D & Carty G, “Comparative Analysis of Low Speed Live Occupant Crash Test Results in Current Literature,” Proceedings of the Canadian Multidisciplinary Road Safety Conference XIV; June 27-30, 2004; Ottawa, Ontario.
5.
Haight, W. R., Szabo, T. J., Collision Reconstruction for the Medical Practitioner, Texas A&M University, Texas Engineering Extension Service (TEEX), 1998-2000
16. Ewing JL, Thomas DJ, Lustik L, Muzzy WH, Willems GC and Majewski P, "Dynamic Response of the Human Head and Neck to +Gy Impact Acceleration," SAE Number 770928, Proceedings of the 21st Stapp Car Crash Conference, 1977.
6.
Kato D, Kimpara H, Nakahira Y & Iwamot M, “Effects of Controlled Muscle Activations on Human Head-Neck Responses During Low-Speed Rear Impacts,” Accident Reconstruction Journal, Vol 27, No 3, May/June 2017.
7.
Code of Federal Regulations, Title 45 Public Welfare, Part 46 Protection of Human Subjects, 46.102 part (i) minimal risk.
8.
Brault JR, Wheeler JB, Siegmund GP and King DJ, “Human Subject Protection in Low-Speed Rear-End Automobile Testing,” Presented at the 24th International Workshop on Human Subjects for Biomechanical Research, November 3, 1996.
9.
Cormier J, Gwin L, Rienhart L, Wood R & Bain C, “A Comprehensive Review of Low Speed Rear Impact Volunteer Studies and a Comparison to Real-World Outcomes,” Spine, DOI: 10.1097, PMID 29489567, ISSN 0362-2436, Feb 2018.
10. Wilson LA & Haight S, ”Kinematics of Braced, Un-braced, and Out-of-Position Occupants in Low-Speed Bumper-toBumper Rear Impacts,” Collision-The International Compendium for Crash Research, Vol 12, Issue 2, 2015. 11. Ruberte LM, Cox BS & Lantz S, “The Older Lady Versus the Younger Lady: Female Occupant Kinematics in LowSpeed Rear-End Collisions,” Collision-The International Compendium for Crash Research, Vol 11, Issue 1, 2016. 36 Collision Magazine - Volume 16 Issue 2
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17. Wagner R, “A 30 mph Front/Rear Crash with Human Test Persons,” SAE Paper 791028, Proceedings of 23rd Stapp Car Crash Conference, Society of Automotive Engineers, 1979. 18. Vandiver W & Anderson RD, “Analysis of Crash Data from a 2012 Hyundai Genesis Coupe Event Data Recorder,” Society of Automotive Engineers, Paper 2021-01-0905. 19. Anderson RD & Vandiver W, “Analysis of the Event Data Recorder Information Obtained in Crash Testing of Supported and Pre-Supported Hyundai Vehicles: a 2015 Elantra Sedan and a 2012 Genesis Coupe,” Collision-The International Compendium for Crash Research, Vol 16, Issue 1, 2022. 20. McConnell, Whitman E., et al. “Analysis of Human Test Subject Kinematic Responses to Low Velocity Rear End Impacts, Society of Automotive Engineers 930889 Warrendale, PA. 1993. 21. McConnell, Whitman E., et al. “Human Head and Neck Kinematics After Low Velocity Rear-End Impacts – Understanding “Whiplash”, Society of Automotive Engineers 952724 Warrendale, PA. 1995. 22. Siegmund, Gunter P., et al. “Head/Neck Kinematic Response of Human Subjects in Low-Speed Rear-End Collisions.” Society of Automotive Engineers, 973341, Warrendale, PA. 1997. 23. Kelfer OP, Layson PD and Reckamp BC, “The Effects of Seated Position on Occupant Kinematics in Low-speed
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rear-end Impacts,” SAE Paper 2005-01-1204, in Accident Reconstruction 2005 (SP-1930), Society of Automotive Engineers, Inc., Warrendale, PA, 2005. 24. Biomechanics, Principles and Applications, Second Edition, Peterson DR and Bronzino JD editors, ISBN-13: 9780849385346, CRC Press, 2007.
30. Wheeler, Jeffrey B., Smith, Terry A., et al. “Validation of the Neck Injury Criterion (NIC) Using Kinematic and Clinical Results From Human Subjects in Rear-End Collisions.” ITCOBI Conference – Goteborg, September 1998. 31. Independent Crash Test, T22810. “Toyota Corolla striking Pontiac LeMans.” July 25, 1997.
25. Abbreviated Injury Scale, Association for the Advancement of Automotive Medicine, Des Plaines, IL 2005.
32. Independent Crash Test, T241-04. “Nissan 240 SX striking Honda Prelude.” February 25, 1999.
26. Pike, Jeffrey A., “Automotive Safety: Anatomy, Injury, Testing & Regulation.” 1990 Society of Automobile Engineers, Inc.
33. Independent Crash Test,T241-05. “Nissan 240 SX striking Honda Prelude.” February 25, 1999.
27. NHTSA, Injury Risk Curves and Protection Reference Values,” Final Economic Assessment, FMVSS No. 201, Upper Interior Head Protection, June 1995. 28. Lam, Tak, Ivarsson, B.J., “Vehicle Rear Impacts and Spinal Disc Herniations in Occupants: Is there a Basis for Causation. Society of Automotive Engineers 217-01-1458 Warrendale, PA, 03/28/2017. 29. Svensson, M.Y., Bostrom, O., et al. “Neck Injuries in Car Collisions – A Review Covering a Possible Injury Mechanism and the Development of a New Rear Impact Dummy.” WAD ’99 Compendium/Traffic Safety and Auto Engineering.
34. Bailey, M. N. et al. “Data and Methods for Estimating the Severity of Minor Impacts”, Accident Reconstruction: Technology and Animation V, Society of Automotive Engineers Special Publication SP-1083, pp. 139-175, February 1995. 35. Furbish, Christopher and Welcher, Judson, et al. “Occupant Kinematics and Loading in Low Speed Lateral Impacts. Society of Automotive Engineers Special Publication 2019-01-1027, Published 02, Apr 2019.
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Vehicles, VIN's, Certification Labels, and parts
What “Model Year” is it?? Daniel W. Vomhof III 4N6XPRT Systems
T
his article is a result of some recent discussions and research by individuals on the Crash Forum (www.crashforum.info) with respect to, for example which direct-to-module CDR Tool cable is needed for a download based on the “model year.” As such, this will concentrate on the model year portion of the VIN (and other vehicle labels) trying to answer the question of “What model year is it, and which equipment/part/cable is therefore needed?” Please keep in mind that every time we think we have a system, the automotive industry finds a way .... so please don’t shoot the messenger.
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Background One of the original purposes of the VIN system was to enhance public safety by deterring vehicle theft based on the assumption that drivers of stolen vehicles are more likely to operate those vehicles unsafely and thus be involved in vehicle crashes. The current 17-character VIN
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system embodied in 49CFR565 (“part 565”) continues to serve this purpose and, as stated in Part 565, also serves… 1. “to increase the accuracy and efficiency of vehicle recall campaigns.” 2. The VIN has also become the key identifier in data systems that track such things as: 2.1 compliance with federal importation regulations, 2.2 vehicle registrations, 2.3 insurance coverage, and 2.4 motor vehicle crashes. Within the automotive industry, the vehicle model year is nominally the “vehicle design” year specifications to which
the vehicle is built. The VIN indicates a “Design” model year with character ten of the VIN in combination with (since 2010 when the Year Code reset to “A”) character 7. Per NHTSA’s Final Rule on Vehicle Identification Number Requirements, as of 2010, it is required that VIN position 7 be alphabetic for passenger cars and multipurpose passenger vehicles and trucks with a gross vehicle weight rating of 4536 kg (10,000 lbs) or less (prior to 2010 this position must be numeric for these vehicles, while either an alphabetic or numeric character can be used in this position for other vehicles covered by the standard). From 49CFR565.12 (m): “… Model year means the year used to designate a discrete vehicle model, irrespective of the calendar year in which the vehicle was actually produced, provided that the production period does not exceed 24 months. …” While for a short period of time the CFR required/stated that it was meaning 2 calendar years, they reverted to the
24 month time period irrespective of calendar year due in part to a January 7, 2005 letter from General Motors which stated in part it is common practice for a manufacturer to use a model year designation for the production of a vehicle that spans over three calendar years, particularly when a manufacturer introduces a substantial design change for a vehicle model. This practice allows the manufacturer to “obtain early experience with the performance of a new model and to correct problems, including potential safety defects, before a large volume of vehicles has been delivered to dealers and customers.”
Orientation While the VIN may be found in several places on a vehicle, the two most common places I look for a VIN is on the driver’s side front dash near the lower corner of the front window (Figure 1), and on the certification label that is usually (A) on the driver’s side A pillar covered by the front door, (B) on the driver’s door below the window level on the B pillar side, or ( C ) on the B pillar covered by the driver’s door below the side window level (Figure 2). While most of the vehicles have the certification label in one of these three places, on select vehicles you can also find the
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1 Tiguan was built at one of two plants in Germany from 2008 to 2018. A second generation Tiguan with a longer wheelbase went into production at VW’s Mexico plant around June 2016 and so, for a time, the Tiguan designated as a MY 2017 (VIN character H) and MY 2018 (VIN character J) had overlapping production dates. In the case of the Tiguan, a careful examination of the VIN will reveal which "model" it is by the WMI and by the Plant code. Unfortunately, this will not always be the case with "overlapping models" with the same model year code." While we can identify the plant through the VIN, the model year designation may still be something of a “moving target.” The MY 2017 Tiguan could have been built during the period 5/2016 through 11/2017 and the MY 2018 could have a production date between 4/2017 and 9/2018. As you can see, during a large part of calendar year 2017 production dates, the specific vehicle, depending mainly on the production plant at that point, could be designated a MY 17 or MY18. This production “anomaly” caried over for majority of production dates in 2018 where a Tiguan could have been designated as MY 2018 or MY 2019 as seen in the VIN MY digit. A review of some 300 randomly selected VW Tiguans by VIN and certificaton sticker for model years 2017- through 2020 developed a pattern such that the build calendar date from the certification stickers fell within the appropriate 2 year period, however, many fell outside the production calendar date. Ultimately, depending on where the Tiguan was built or its generation… a 2017 (H) Tiguan could have a production date between 5/2016 and 11/17 •
a 2018 (J) Tiguan could have a production date between 4/2017 and 9/18
•
a 2019 (K) Tiguan could have a production date between 1/2018 and 8/19
•
a 2020 (L) Tiguan could have a production date between 8/2019 and 9/20
Examples of the certification sticker production date to designated MY for the Tiguan are seen in Figure 6.
the individual looking to download data having to make sure they have more than one direct to module cable on hand since the model year indicator may not be the deciding factor when it comes to identifying the right cable. In Summary Since 1981, the Vehicle Identification Number (VIN) has been structured with 17 characters, some of the positions and values being mandated, but most being left “up to” the manufacturer to a greater or lesser extent. The 10th character identifies the manufacturer designated Model Year of the vehicle. Model Year means the year used to designate a discrete vehicle model, irrespective of the calendar year in which the vehicle was actually produced, provided that the production period does not exceed 24 months. (49CFR565.12 (b)) If you are relying upon the VIN designated MODEL YEAR to identify the cable(s) that will be needed to complete a download, you might want to make sure you have the cables for the immediately preceding and following Model Years on hand as well to make sure you don’t get out to the vehicle and experience an unwelcome production date related “surprise.” This is the unfortunate reality of the industry in which we are “playing.” For Additional Reading and Reference 1. https://www.ecfr.gov/current/title-49/subtitle-B/ chapter-V/part-565 2. NHTSA Letter of Explanation as to “Model Year” -https://www.nhtsa.gov/interpretations/modelyearjoneslet4 3. Rescind determination of “calendar year” as part of the “model year” statement - https://www.federalregister. gov/documents/2005/05/06/05-9140/vehicle-identification-number-requirements-technical-amendment 4. WMI, Country Codes, etc - https://en.wikipedia.org/ wiki/Vehicle_identification_number
As it might relate to, for example, direct-to-module cables for the Bosch CDR Tool, there is an airbag control module changeover suggested for this period which would leave
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Tesla EDR Tool Kit
EDR Data can be retrieved from all Tesla Model S, Model X, Model 3, and Model Y vehicles. Tesla Roadster, which was produced from 2008 to 2012, is equipped with a RCM but does not have an EDR.
The EDR Retrieval Hardware Kit for Tesla vehicles contains all the hardware required to download the Event Data Recorder (EDR) data that may be stored in all Tesla Model 3, Model S, Model X, and Model Y vehicles. This is the only kit that contains genuine Tesla EDR cables.
Available at Crash Data Group www.crashdatagroup.com (800) 280-7940 crash@crashdatagroup.com
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MY
RN TU
AT
E TH
L EE WH
WHAT IS "30" how and why should we use it? Richard C. Rinker
I
recently had the pleasure of flying from Dallas, Texas to Ontario, California. I was seated between a gentleman who explained the benefits of Ivermectin in the current health situation and a woman traveling with a 3-year-old child who loudly protested the effect of changes of air pressure on his ears. She apparently failed to grasp the value of a therapeutic dose of a fine Kentucky Bourbon in such a situation. In self-defense I allowed my mind to ponder my favorite number, 30, and its place in the grand scheme of life. By “30” of course, I refer to the value with which we are all familiar, the basic Slide to Stop skid speed formula. At least those of us residing in the U.S. We are all familiar with the Slide to Stop formula S=√30df where S=Speed in units of Miles Per Hour (MPH), d = distance of the slide in feet, f = coefficient of friction, and 30 = what? Most of us have been taught 30 is a constant derived from the combination of Kinetic and Work Energy formulas, such that Energy = Energy, so Kinetic Energy (KE) = ½MV² = work energy = Fd (Lofgren, M. (1993) IPTM, Pg 11-13). I’m not going to derive the entire formula here. We should have all seen it at one time or another, but as a reminder, mass = weight/gravity, and, in Earth based collisions, gravity ≈ 32.2 FPS/S. We call it a constant because, well, it’s constant. It does not vary from California to Alaska to Maine to Hawaii.
maintains 30 is a constant. Why? Because it is consistent on Earth and that’s what everyone calls it. This may come from the landmark decision People v. Herman, 20 NYS 2nd, 149 (1940) in which the court recognized 30 to be a mathematical constant. The court held in Herman: “30 = The gravitational constant, 32.2 feet per second per second, doubled and multiplied by a factor, (3600/5280)2 which transforms the miles per hour in V2 to feet per second” However, to truly be a constant, it must be the same universally. Gravity, however, is not a constant universally (other than Einstein’s Gravitational Constant, but that’s for another discussion. On Earth, the acceleration of gravity is generally held as 32.2 FPS². On the Moon, it is 0.16 FPS. On Mars it is 3.71 FPS². Yes, I realize it will be a very long time before we need to work a collision on any of these celestial bodies. That is not the point. The point is, if a value, any value, varies from place to place or situation to situation, it cannot be considered a constant. But as long as we maintain our frame of reference as operating on the Earth, we can probably get away with calling it a constant, for our purposes.
The other school of thought holds that 30 is really a derived conversion factor which changes measurements of the change of distance with respect to time from units of feet per second (FPS) to miles per hour (MPH). As we follow the derivation of the slide to stop formula, we get to a point where we have a term, 2g, expressed as 2x32.22 But is it really a math- = 64.4 FPS² which we need to divide by (5280 feet/3600 ematical Constant? seconds)² to convert a value from FPS to MPH or as we There are two are more familiar with it, 1.467²= 2.15, 64.4/2.15, which schools of equals approximately 29.95 depending on how one hanthought on dles decimals. We then, of course round up to get the this. One “30” with which we are all familiar. This shows “30” to be school a derived conversion factor changing velocity in Feet per Second to speed in Miles per Hour. We call it a “factor”
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because it is a number by which we multiply other numbers. This is also the answer to the question how does S=√30df which contains variables of distance in feet and friction with no obvious units of measure but no units of speed or velocity provide the user with an answer in MPH? Thus, regardless of which school one follows, Constant or Conversion Factor, 30 is a derived value which comes from the conversion of FPS to MPH. The units of measure of the rate of change of distance with respect to time expressed in units of MPH is hidden in the derivation of the number 30. The fact that the court in Herman specifically analyzed the use of the number 30 to the exclusion of all other numbers suggests that only 30 is the tested and accepted value to be used in this application. This brings me to the actual use of the slide to stop formula. We use the formula to estimate the minimum speed of a vehicle sliding with all wheels locked. At this point, I am not including adjustments for vehicles with defective brakes, grades or other adjustment needed to handle special conditions. We will get to that shortly. We are taught the ideal method to estimate speed of a skidding vehicle is to track the movement of the center of mass of the vehicle in question. In a perfect world involving a vehicle skidding with locked tires, we should measure all tire marks, plot them on a scale diagram, locate the center of mass of the vehicle, track its’ movement during the skid, measure the distance the center of mass moves, determine the average drag factor affecting the center of mass of the involved vehicle, apply the appropriate average drag factor or deceleration rate over the measured distance and estimate the initial speed of the vehicle based upon the average deceleration over the given distance. This method works for a vehicle skidding in a straight line on one consistent surface. Now let us consider a special condition in which a vehicle skids with all tires locked from one surface onto a second surface, sequentially, with a different drag factor, or a third, or fourth, etc. To deal with this situation, we typically track the movement of the center of mass to determine the speed loss of the vehicle on each surface individually and combine them using Pythagoras’ gift to Accident Reconstruction, the Pythagorean Theory, a2+b2=c2. We could also solve the problem by treating it as an acceleration problem, solving for V0 (Fricke, Northwestern University (1990) page 60-8) if we know the acceleration rate and distance. If we want to show off, we could even solve it using vectors and right triangles. But one variable we need to use in all the methods is we need to determine the average drag factor (or acceleration rate) acting on the center of mass of the vehicle. Now, consider another special case where we have a vehicle skidding on two surfaces having dissimilar drag factors at the same time, say, right side on wet, muddy concrete and the left side on clean, dry asphalt. In this case, I am ignoring, for the moment, rotation of the vehicle caused by the unbalanced drag factors. We will discuss that complication later. Once again, I find two schools of thought in finding the resolution to the problem of determining the minimum estimated speed of the vehicle leaving the skid marks. One school says the investigator should measure each skid, plot them on a diagram, determine the distance of the movement of the center of mass of the vehicle, then determine the drag factor for the left side and right side independently, add the respective drag factors and divide by two to determine the average drag factor acting on the center of mass of the vehicle. We then use the traditional slide to stop formula to estimate the speed. In practical application, this would look like S=√30dfa where fa is the average f acting on the center of mass of the vehicle. A modification of the traditional formula would be S=√(30d ((f1+f2)/2)). In the real world, both formulas are the same thing, just written differently. This formula has two advantages. First, it makes use of the distributive property of division, that is it divides two drag factors using the average f acting on the vehicle over the distance traveled by the center of mass. Second, it maintains the derived value, “30” unaltered.
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Nissan Automobile EDR Recording Characteristics David M. Hallman M.S., P.E. Billy S. Cox, Jr. Robert D. Anderson, M.S.
A
bstract In our prior work entitled, “Nissan SUV EDR Recording Characteristics.” [1] first published in Volume 14 Issue 1 of Collision Magazine, we reported on our research where we developed and executed a repeatable test method for determining Nissan’s non-deployment trigger threshold. We also evaluated/confirmed 50 Collision Magazine - Volume 16 Issue 2
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the published [2] non-deployment event recording order. The purpose of additional testing outlined in this paper was to further evaluate the Nissan non-deployment trigger threshold, to compare the recording behavior of the previously tested Nissan SUV (Pathfinder) to Nissan passenger cars (Versa) and to further verify the Nissan recording order.
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During the prior testing with the subject 2013 Nissan Pathfinder, the event record did not include up to 45 msec of the initial crash pulse during low-speed frontal non-deployment crashes, whether the target was a second vehicle or fixed a barrier. Further, we observed that the event record missed up to 15 msec of the crash pulse in low-speed, rear event threshold crash events. The testing conducted in this study revealed that the recording time offset found in the Nissan SUV is also exhibited in the tested passenger car. The testing conducted in this study also determined that the recording threshold for non-deployment events is 1g in less than 30msec. We verified that the tested passenger car recorded non-deployment events in the same order as the Nissan SUV evaluated during the prior testing. Introduction Our prior published work was based on the results from a single vehicle test series using a Nissan Pathfinder SUV. At the conclusion of that testing, we pondered whether the same behavior would be observed in Nissan passenger cars. The testing described here was performed utilizing Nissan Versa passenger cars. The prior testing also raised questions as to whether the observed recording threshold behavior is influenced by off-longitudinal axis or roll axis acceleration as all the prior test impacts were essentially aligned with the vehicle x-axis resulting in purely longitudinal accelerations. Some of the tests described here were performed at 30 degrees and 45 degrees to the barrier. Materials and Test Equipment The tests that are the focus of this study were conducted on two separate occasions. The first set of tests was performed in August of 2020 in Whitehall Texas. The second set of tests was conducted in advance of the 2021 SATAI crash program in Glendale Arizona in February 2021. The test vehicle in both test sets was a 2014 Nissan Versa, VIN 3N1CN7AP2EL811198, which was purchased as a used vehicle. In addition, a 2020 Nissan Versa, VIN 3N1CN8EVXLL882581, was subjected to a single car-to-car impact during the Texas test series. A total of nine low-speed crash tests were conducted in August 2020 in Texas and ten low-speed crash tests were conducted in Arizona. The 2014 Nissan Versa was occupied by an instrumented human volunteer for all tests. In keeping with the concept that live humans can safely be subjected rear-end and broadside impacts with deltaVs up to about 10 mph [3-15] and 20 mph delta-V frontal impacts [16, 17] all tests were planned and conducted to produce less than 10 mph delta-Vs. www.collisionpublishing.com
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3. Szabo TJ and Welcher JB, “Human Subject Kinematics and Electromyographic Activity During LowSpeed Rear Impacts,” SAE paper 962432, Proceedings of the 40th Stapp Car Crash Conference, Albuquerque, NM, November 1996. 4. McConnell WE, Howard RP, Poppel JV, Krause R, Guzman HM, Bomar JB, Raddin JH, Benedict JV, and Hatsel CP, “Human Head and Neck Kinematics After Low Velocity Rear-End Impacts - Understanding ‘Whiplash’,” SAE Paper 952724, Proceedings of the 39th Stapp Car Crash Conference, San Diego, CA, November 1995. 5. West DH, Gough JP and Harper GTK, “Low Speed Rear-end Collision Testing Using Human Subjects,” Accident Reconstruction Journal, May/June 1993. 6. Szabo TJ and Welcher JB, “Human Subject Responses to Various Acceleration Fields,” Presented at the LowSpeed Collision TOPTEC”, Society of Automotive Engineers, Vancouver, BC, August 1996. 7. Meyer S, Weber M, Castro W, Schilgen M and Peuker C, “The Minimal Collision Velocity for Whiplash,” in Whiplash Injuries: Current Concepts in Prevention, Diagnosis and Treatment of Cervical Whiplash Syndrome, Robert Gunzberg and Marek Szpalski, ed., Lippencott-Raven, Philadelphia, 1998. 8. Mills D & Carty G, “Comparative Analysis of LowSpeed Live Occupant Crash Test Results in Current Literature,” Proceedings of the Canadian Multidisciplinary Road Safety Conference XIV; June 27-30, 2004; Ottawa, Ontario.
ings of the 8th Stapp Car Crash and Field Demonstration Conference, October 1964. 13. Zaborowski AV, "Lateral Impact Studies - Lap Belt Shoulder Harness Investigations," SAE Number 650955, Proceedings of the 9th Stapp Car Crash and Field Demonstration Conference, 1965. 14. Ewing JL, Thomas DJ, Lustik L, Muzzy WH, Willems GC and Majewski P, "Dynamic Response of the Human Head and Neck to +Gy Impact Acceleration," SAE Number 770928, Proceedings of the 21st Stapp Car Crash Conference, 1977. 15. Furbish C., Welcher J., Brink J., Jones B., Swinford S & Anderson RD, “Occupant Kinematics and Loading in Low-Speed Lateral Impacts,” SAE Technical Paper 2019-01-1027, 2019, doi:10.4271/2019-01-1027. 16. Wagner R, “A 30 mph Front/Rear Crash with Human Test Persons,” SAE Paper 791028, Proceedings of 23rd Stapp Car Crash Conference, Society of Automotive Engineers, 1979. 17. Vandiver W & Anderson RD, “Analysis of Crash Data from a 2012 Hyundai Genesis Coupe Event Data Recorder,” Society of Automotive Engineers, Paper 2021-01-0905. 18. Anderson RD & Vandiver W, “Analysis of the Event Data Recorder Information Obtained in Crash Testing of Supported and Pre-Supported Hyundai Vehicles: a 2015 Elantra Sedan and a 2012 Genesis Coupe,” Collision-The International Compendium for Crash Research, Vol 16, Issue 1, 2022.
9. Haight, W. R., Szabo, T. J., Collision Reconstruction for the Medical Practitioner, Texas A&M University, Texas Engineering Extension Service (TEEX), 19982000 10. Lam, T. and Ivarsson, B., "Vehicle Rear Impacts and Spinal Disc Herniations in Occupants: Is there a Basis for Causation?" SAE Paper 2017-01-1458, 2017, doi:10.4271/2017-01-1458. 11. Cormier J, Gwin L, Rienhart L, Wood R & Bain C, “A Comprehensive Review of Low-Speed Rear Impact Volunteer Studies and a Comparison to Real-World Outcomes,” Spine, DOI: 10.1097, PMID 29489567, ISSN 0362-2436, Feb 2018. 12. Zaborowski AV, "Human Tolerance to Lateral Impact with Lap Belt Only," SAE Number 640843, Proceed-
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The Lost Energy of Planar Impact Mechanics Micky Marine SSi Phoenix, Inc.
P
lanar impact mechanics (PIM), as applied to automobile accident reconstruction, comprises a number of various formulations that have been presented in the open literature (Brach [1], Woolley [2], Ishikawa [3], Smith [4], Steffan & Moser [5], etc.). PIM formulations have an appeal to accident analysts in that they provide algebraic solutions to non-collinear and eccentric automobile impact configurations. There has been an ongoing interest in breaking down the energy loss that can be calculated within PIM methods to terms that relate to crush energy (volume strain) and energy dissipation due to sliding, shearing, entanglement, etc. Brach has presented equations that separate energy loss into normal 66 Collision Magazine - Volume 16 Issue 2
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and tangential contributions, and Carpenter & Welcher [6] have expanded on this, presenting equations, for what they call isotropic conditions, that further separate the energy loss into volume strain and surface sliding categories. In this article, we will delve into PIM energy loss by examining what constitutes isotropic and anisotropic conditions, presenting examples of each in impulse space and relative velocity-impulse component diagrams. Additionally, the derivation of various forms of energy loss equations that can be derived from the PIM formulations are evaluated with an eye toward the effects Newton’s kinematic and Poisson’s kinetic restitution hypotheses have on them.
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Assumptions and Energy Loss Equations The assumptions that underly the PIM formulations typically used in automobile accident reconstruction are: •
PIM is based on rigid-body mechanics – vehicle masses and moments of inertia do not change
•
The distributed forces acting on the respective vehicles in the contact region are resolved to an impulse acting at a single point (herein called the impulse center (IC) – see Figure 1)
•
The impulse acting on each vehicle occurs instantaneously
•
Due to the instantaneously applied impulses, changes in vehicle velocities are discontinuous
•
The impulses induce negligible displacement and rotation of the involved vehicles (i.e., the IC is fixed relative to the respective vehicles)
•
Deformation of the respective vehicles is not modeled and is considered negligible
•
Tire forces and other external forces are assumed to be negligible
In addition to the above assumptions, two constraint relationships are necessary in order to solve the set of PIM equations that result from the derivation of the equations of motion. These constraints are typically in the form of a restitution constraint (εN) along a normal axis and a constraint applied orthogonal to the normal axis (a tangent axis), often in the form of an impulse ratio (µ), a slip ratio (σ) or a tangential restitution (εT).
Figure 1: Planar Impact Mechanics Diagram www.collisionpublishing.com
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The Crash Hub Expert Directory The Crash Hub is a specialized expert directory for crash reconstructionists and traffic investigators. This directory allows the user the ability to search, review, and retain vehicle crash experts around the world. Our directory creates hundreds of leads for new cases! The Crash Hub is also much more than an expert directory site because each member of The Crash Hub has the ability to add meaningful content to the site in the form of articles, events, training classes, photo albums, and videos. The Crash Hub can also be used as job search site and a classified ads directory.
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Search Engine The Crash Hub has a powerful search engine allowing you to locate experts around the world with a simple click of your mouse. You can search by expertise, location, name, or any keyword.
Search Results The Crash Hub search results profile the globe and pin the location of every active member. Simply move your mouse over the pin and that expert will be displayed. The results map has full “zoom” capabilities to zero in on the location you are looking for.
Member Dashboard Each member has full access and control of their professional profile in The Crash Hub. Add your photo, company logo, C.V., full contact information, specialties, publish articles, post events, job listings, photo albums, videos, and even post classified ads. You can even check how many people have viewed your professional profile.
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Utilizing EDR data to determine the effects of hard braking on Delta-V calculations in low-tomoderate speed impacts Shannon CrowlEy, Camila Marrero Torres, Alex Kazmierczak, Christopher J. Furbish and Bryan Randles Aperture Justin Brink Forensic Science and Biomechanics
A
bstract Four instrumented low-speed collinear impacts were conducted to study the effects of bullet vehicle hard braking in tests with Delta-Vs ranging from 5.0 to 12.4 mph. The bullet vehicle’s deceleration from hard braking was used to determine the effective bullet vehicle Delta-V for momentum analysis when applied to the target vehicle. In all tests, the bullet vehicle had maximally applied braking prior to and throughout the duration of the impact. Several methods for analyzing EDR data to determine bullet vehicle deceleration and impact durations are presented. The deceleration was used to calculate the effective bullet vehicle Delta-V and was then compared to the reference Delta-V from the instrumentation mounted within the vehicle. In all test impacts, the EDR-reported Delta-V overestimated the bullet vehicle effective Delta-V. The methods presented in this paper allow for a more accurate calculation of the target vehicle’s Delta-V for cases where bullet vehicle hard braking is evident and EDR data in the target vehicle are unavailable. When performing a simple momentum analysis of an impact where the impacting vehicle exhibits hard braking, using the EDR-reported Delta-V may result in an artificially high Delta-V on the corresponding vehicle, based on our testing 1.1-1.8 mph, up to 48%. Literature Review The accuracy of Event Data Recorder (EDR) data has been well documented, however the effects of hard braking on Delta-V have been less robustly studied. [1,2,3] For example, there is known error in reported speed due to wheel slip during deceleration due to hard braking. A study of late model General Motors (GM) vehicles found that braking at lower levels that did not activate the ABS system underreported the vehicle speed, and in cases where the ABS system was activated, the vehicle speed was underreported by approximately 8-18%. [4] An analysis of the accuracy of EDR-reported data during braking in a 2010 Ford Flex found that in all test cases, the EDR-reported speed 82 Collision Magazine - Volume 16 Issue 2
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In collisions with evidence of hard braking, the use of EDR-reported Delta-V can lead to an over-estimation of the calculated Delta-V on the target vehicle. A recent publication by Vandiver and Anderson examined two crash tests and the effects of tire friction from the bullet vehicles. It was found that the Delta-V from tire friction resulted in the same speed change from skidding over a tenth of a second, 1⅔ mph. [8] The present study aims to provide methods to calculate the bullet vehicle effective Delta-V for use in momentum analysis for more accurately determining the resulting target vehicle Delta-V. Theoretical Calculations In low-speed impacts, hard braking can account for a substantial portion of the vehicle's deceleration and thus, overreport the Delta-V as a result of the collision. As a consequence, use of the bullet's EDR-reported Delta-V to examine the severity of the impact experienced by the target vehicle can result in an overrepresentation, or overcalculated DeltaV. In order to more accurately calculate the Delta-V experienced by the target vehicle, when utilizing EDR data obtained from the bullet vehicle, the effective Delta-V needs to be determined for use in a momentum and restitution equation. The total Delta-V of the bullet vehicle is the sum of the Delta-V due to the collision, or the effective Delta-V
(∆VEffective), and the Delta-V component due to hard braking (VL). [8] Equation 1: ∆VTotal=∆VEffective+∆VL The Delta-V component due to hard braking (VL) can be calculated using the drag factor (µ), acceleration of gravity (g) and impact duration (t), according to the formula below. Equation 2: ∆VL=µ×g×t For cases where there is no EDR or pre-crash data available, the Delta-V component due to hard braking (VL) can be calculated theoretically and applied as long as there is evidence of hard braking. In these cases, a range of deceleration can be used. The theoretical VL due to hard braking was calculated using the above formula based on a range of impact duration (90-150 ms) and deceleration (0.5-0.9 g). This range of deceleration was determined by referring to Ruth et al. [4] However, the deceleration for high performance ABS could be as high as 1.2. [9] Deceleration (g) Crash pulse duration (ms)
was less than the speed reported by GPS. [5] An analysis of the 2010 and 2011 Toyota Camry during braking attributed positive differences between GPS and EDR data to speed data refresh rates and negative differences due to wheel slip as expected during braking. [6] Ruth et. al offers a method to calculate the range of speed at impact based on EDR pre-crash data. The article provides an outline to calculate speed loss from the last reliable data point. [7]
90 100 110 120 130 140 150
0.5
0.6
0.7
0.8
0.9
0.99 1.10 1.21 1.32 1.43 1.54 1.65
1.19 1.32 1.45 1.58 1.71 1.84 1.98
1.38 1.54 1.69 1.84 2.00 2.15 2.31
1.58 1.76 1.93 2.11 2.28 2.46 2.63
1.78 1.98 2.17 2.37 2.57 2.77 2.96
Table 1: Delta-V Component due to Hard Braking, VL (mph) In cases where pre-crash EDR data is available, there are various methods that can be used to find the effective Delta-V of the bullet vehicle, using the impact duration and deceleration. 1. Find the impact duration. Three methods of finding the impact duration from the EDR report were compared (Table 4). First, the EDRreported time of maximum Delta-V. Second, according to the definition of the end of event time from NHTSA 49 CFR Part 563. [10] Third, the end of event time determined from the collision acceleration data in the EDR report.
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1. Vandiver, Wesley, and Robert Anderson. Analysis of Crash Data from a 2012 Hyundai Genesis Coupe Event Data Recorder. No. 2021-01-0905. SAE Technical Paper, 2021. 2. Lawrence, Jonathan M., et al. "The accuracy and sensitivity of event data recorders in low-speed collisions." SAE Transactions (2002): 941-951. 3.
Bortles, W., et al. "A Compendium of Passenger Vehicle Event Data Recorder Literature and Analysis of Validation Studies.” SAE Technical Paper 2016-011497 (2016).
4. Reust, Timothy J., and James M. Morgan. "The accuracy of speed recorded by an [EDR] SDM and the effects of brake, yaw and other factors." Collision: the international compendium for crash research 1.1 (2006): 9-15. 5. Ruth, Richard, and Jeremy Daily. "Accuracy of Event Data Recorder in 2010 Ford Flex During Steady State and Braking Conditions." SAE International Journal of Passenger Cars-Mechanical Systems 4.2011-010812 (2011): 677-699. 6. Ruth, Richard, Wade Bartlett, and Jeremy Daily. "Accuracy of event data in the 2010 and 2011 Toyota Camry during steady state and braking conditions." SAE International journal of passenger cars-electronic and electrical systems 5.1 (2012): 358-372. 7. Ruth, Rick, and Bill Wright. "Using EDR Pre-Crash Data to Calculate a Range for Speed at Impact." Accident Reconstruction Journal 27.3 (2017). 8. Vandiver, Wesley and Robert Anderson. “Event Data Recorder Delta V: The Effect of Tire Friction.” Collison Magazine, The International Compendium for Crash Research 16.1 (2022). 9. Tingwall, Eric. “2019 Chevrolet Corvette ZR1 vs. 2018 Porsche 911 GT2 RS.” Car and Driver, 29 Nov. 2021, https://www.caranddriver.com/reviews/comparison-test/a22516381/2019-chevrolet-corvette-zr1vs-2018-porsche-911-gt2-rs-comparison-test/.
11. Kusano, Kristofer D., and Hampton Gabler. "Method for estimating time to collision at braking in realworld, lead vehicle stopped rear-end crashes for use in pre-crash system design." SAE International Journal of Passenger Cars-Mechanical Systems 4.2011-010576 (2011): 435-443. 12. Ruth, Rick, and Bill Wright. "Using EDR Pre-Crash Data to Calculate a Range for Speed at Impact." Accident Reconstruction Journal 27.3 (2017). 13. Emori, Richard I., and Junji Horiguchi. Whiplash in low speed vehicle collisions. No. 900542. SAE Technical Paper, 1990. 14. Cipriani, A. L., et al. "Low speed collinear impact severity: a comparison between full scale testing and analytical prediction tools with restitution analysis." SAE Transactions (2002): 625-639. 15. Hampton, Carolyn E., and Hampton C. Gabler. "Evaluation of the accuracy of NASS/CDS Delta-V estimates from the enhanced WinSmash algorithm." Annals of Advances in Automotive Medicine/Annual Scientific Conference. Vol. 54. Association for the Advancement of Automotive Medicine, 2010. 16. Tsoi, Ada, et al. "Validation of event data recorders in high severity full-frontal crash tests." SAE International Journal of Transportation Safety 1.1 (2013): 76-99. 17. Niehoff, Peter, et al. "Evaluation of event data recorders in full systems crash tests." Proceedings of the 19th International Conference on the Enhanced Safety of Vehicles. 2005. 18. Wusk, Grace, and Hampton Gabler. "Evaluation of vehicle-based crash severity metrics using Event Data Recorders." 25th International Technical Conference on the Enhanced Safety of Vehicles (ESV) National Highway Traffic Safety Administration. 2017. 19. Anderson, Robert D., et al. "Effect of braking on human occupant and vehicle kinematics in low speed rear-end collisions." SAE transactions (1998): 629640.
10. NHTSA. Code of Federal Regulation (CRF) 49: Part 563 – Event Data Recorders. [Online] Available: https://www.ecfr.gov/current/title-49/subtitle-B/ chapter-V/part-563
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Crash Data and Images Available After Automotive Repair with Airbag Control Module Replacement Robert Anderson Biomechanics Analysis
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A
bstract In the following case example, it is demonstrated that a VCH/PCS equipped Toyota/Lexus automobile still had accessible PCS FFD data and images even after the ACM has been discarded as part of the postcrash repair. Introduction Since their introduction in the 1990s, Event Data Recorders (EDRs) have become a common source of important data for those investigating or analyzing crash events. For the Toyota family of automobiles, additional electronic evidence became available through the introduction of the Vehicle Control History (VCH). A coverage chart for the Lexus and Toyota models sold in the United States is shown in Figure 1 as described in the EDR Tech Series presentation by Dave Hallman. Starting in vehicle Model Year 2013, Toyota quietly added a data recording feature to the Toyota Rav4 which collected a large amount of data based on a wide variety of possible trigger events defined by Toyota. Similar to EDR data, when a trigger event occurs, data preceding, and post trigger data is captured and stored. This data cannot be manually erased but will eventually be overwritten by newer events as the write locations fill up. The recording time, frequency, number of data points captured, and number of events stored prior to overwrite depends on the type of event and is defined in the Toyota Information System (TIS) available by subscription through the Toyota Technical Information website. The data is stored in the airbag control module (ACM) and can be imaged through the DLC using the Toyota Tech Stream software, also available through www. TechStreamSupport.com for an annual fee. Since the introduction in the 2013 Rav4, this recording capability has been added to virtually all Toyota and Lexus models as well as one Scion model (see Figure 1) and a more detailed discussion in crash·ol·o·gy in Collision (Vol 14, Issue 2). As this data has become more widely available across all Toyota models, there are increasing opportunities to put this data to use as a reconstruction tool. Also in Collision Vol 14, www.collisionpublishing.com
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Issue 2, one may find “Toyota Vehicle Control History Case Studies “ The article provided an overview of seven case studies where the VCH data was utilized with and without EDR data to assist in determining the facts of, and reconstructing, a crash. The purpose of that article was to demonstrate some of the potential uses for this data as another tool for the reconstructionist’s toolbox. The VCH data becomes important in situations where EDR data may not be available, including non-contact situations, as well as low speed and low delta-V impacts, such as pedestrian and bicyclist collisions, which often do not qualify for an EDR recording. However, when the automobile has been repaired after a crash for which deployments were commanded, the replacement of the Airbag Control Module (ACM), where the EDR and VCH data is stored, results in loss of access to this key information. Unlike the EDR and VCH data, which is stored in the ACM, the Pre-collision Safety (PCS) images associated with the VCH are stored in the front recognition camera module. The residual data following the replacement of an ACM during repairs was discovered during a recent vehicle inspection of a late model Lexus that was hit in the passenger side after turning left into the path of an oncoming vehicle. Unbeknownst to the crash reconstructionists prior to the inspection, the vehicle had been repaired and returned to service. As expected, the CDR report showed no events, and the VCH showed a small number of events, but none that pre-dated the repairs and presumed replacement of the ACM. However, the PCS read data function retrieved the images related to the crash. Evidently, resetting the forward recognition camera is not part of the repair protocol. As shown in Figure 2 in frames 0 through 20, the images show the Lexus following another left turning vehicle, before the oncoming vehicle becomes visible around the oncoming vehicles waiting to turn left. The post-collision images shown the clockwise rotation of the Lexus from the impact. The trigger for the camera data corresponds to image 10 as “time zero” for this system.
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b osch C DR pr o to o l k it The Bosch CDR Tool is a reliable, versatile, and increasingly powerful industry standard platform that retrieves EDR data from the vast majority of modern vehicles. The CDR Tool software generates a detailed report that has become a vital part of investigations conducted by insurance claims adjusters and Special Investigative Units (SIUs). They are also routinely used by law enforcement agencies and accident reconstructionists. EDR data translated by the Bosch CDR Tool is admissible in court as the CDR reports are used to verify insurance claims and assess vehicle and driver input in the moments leading up to, and during, a crash.
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Expert AutoStats® is currently owned by over 700 private individuals and 300 Law Enforcement agencies in the U.S.A., Canada, and South America. Additional information, brochure, and order from can be downloaded from:
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4N6XPRT StifCalcs® 4N6XPRT StifCalcs puts the NHTSA Crash Test database on YOUR 32 or 64 bit MS-Windows computer PLUS calculates A-B-G values and Test Specific Crush Factors based on the NHTSA test data, with no need for you to get on the internet, all for the price of only $700.00*! Can you do this yourself “for free”?? Only if you value YOUR time at $0.00!!
4N6XPRT BioMeknx is designed as a collection of the Biomechanical data of importance to the Accident Investigator into one easily accessible reference location. It is designed as a program to be useful to ALL accident investigators, not just the Biomechanical expert. The program includes: 1. Over 65 printable illustrations and charts 2. 10 Separate categories or sections of information related to forensic biomechanics 3. Information on walking speeds of people from 17 months to > 65 years 4. Calculation modules for: - segment length from total body height, - segment weights and Centers of Mass (CoM) based on total body weight, - Predicted Maximum Walking Speed based on total height 5. Information was obtained by review of over 65 scientific texts, several of which are now "out of print"
www.4n6xprt.com/4n6bm.htm PROGRAM ORDER FORM (Please Print) Contact Name: ________________________________________________ Company: ____________________________________________________ Street: ______________________________________________________ City:____________________ State:____ Zip:__ __ Country: __________ Phone: (_____) _______________ Fax: (_____) ___________________ E-Mail: ______________________________________________________ Expert AutoStats® 4N6XPRT BioMeknx™ Expert Qwic Calcs® 4N6XPRT Ped & Bike Calcs® 4N6XPRT StifCalcs® Expert VIN DeCoder® (pkg) Expert TireStuf® Order Processing
- $ 675.00 ea. - $ 550.00 ea. - $ 275.00 ea. - $ 375.00 ea. - $ 700.00 ea. - $ 575.00 ea. - $ 85.00 ea.
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Q Deliver via electronic download (Email address Required) Q Ship on USB - $50.00 per disk per program California Sales Tax
- 8.50%
TOTAL (U.S. Dollars)
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Search for vehicles by entering Year, Make, and Model, or by any combination of: Length, Wheelbase, Weight, Body Style, Make, Model, and Impact location
Enclosed is:
Print out data and stiffness for single tests, or a Test Summary Stiffness Report when more than one test meets your search criteria
Card Number: _______________________________________________ Name on Card: _______________________________________________ Signature: ________________________________________________
For more information, program order form, and sample printouts please visit our web site at http://www.4n6xprt.com. You may also call us at (619) 464-3478 M-F, 9a-5p (PST), if you have specific questions.
www.4n6xprt.com/4n6sc.htm
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Please Make Checks*/Purchase Orders Payable to:
4N6XPRT Systems®
8387 University Ave - La Mesa, CA 91942-9342 - U.S.A. FAX: (619) 464-2206 Phone: (619) 464-3478 Web: http://www.4n6xprt.com Checks *MUST* be drawn on a U.S. bank. Orders are shipped within 10 working days of receipt. Prices subject to change without notice. Multiple orders and Package discounts available. Please call for details.
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