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ACCIDENT RECONSTRUCTION Examination and Cross-Examination of Reconstruction Experts By: Brian O. Beverly, Dana H. Hoffman and Michael S. Rainey Young Moore & Henderson, P.A. Raleigh, North Carolina Introduction

The drivers, passengers and eyewitnesses to a motor vehicle accident often present different and sometimes conflicting versions of the same accident. By the time the case is ready for trial, there will be the plaintiff's version and the defendant's version. Each version is influenced by the person's ability to see, hear, perceive, and understand the sequence of events leading up to the accident. Since these factors are hard to quantify, lawyers often seek the technical expertise of an accident reconstruction expert. Accident reconstruction experts generally have the following background or qualifications: -civil or mechanical engineer. -former/retired police officer or highway patrol officer. -private investigator, private sector or military.


Before trial, you will want to gather the following information and documents either by deposing the expert or through written discovery requests to the opposing party: -Expert's curriculum vitae. -A list of other cases the expert has handled. -A list of all cases in which the expert has given deposition or trial testimony. -A list of all courts in which the expert has qualified to give expert testimony. -A list of all courts in which the expert was not qualified to give expert testimony. -The expert's complete file, including all field notes, calculations, measures, drawings or diagrams, notes, conclusions, reports, photographs or videotapes. -All accident-related materials reviewed by the expert, including the accident report and statements. -All lawsuit-related materials reviewed by the expert, including the pleadings, discovery responses, and deposition testimony. -All outside materials reviewed by the expert, including treatises, websites, manufacture materials, and weather statistics. -All verbal information conveyed to the expert. -A copy of any computer program or models generated by the expert. -The results of any tests performed by the expert.



The area of accident reconstruction is particularly amenable to the use of diagrams, photographs, maps, charts, formulas, demonstrations and models. While it is common to use one or more of these visual aides with your own reconstruction expert, you should also consider whether such visual aides can effectively be used to further expose a weakness in the opposing expert's opinions. However, before using this tactic, you must carefully consider whether the illustration will ultimately be more useful to your opponent.


Like other expert witnesses, an accident reconstruction expert must satisfy the prerequisites of Rule 702, which provides: If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion. N.C. Gen. Stat. § 8C-1, Rule 702, North Carolina Rules of Evidence (1988). Specifically, the expert must be qualified to testify in his field and his testimony must be helpful to the jury. State v. Purdie, 93 N.C. App. 269 (1989). In Griffith v. McCall, the North Carolina Court of Appeals upheld the admission of an accident reconstruction expert who held a B.S. and M.S. in civil engineering with a major in traffic engineering; was a registered professional engineer; concentrated exclusively in the field of forensic traffic engineering or accident reconstruction; and had previously performed accident reconstruction analyses. 114 N.C. App. 190 (1994). In addition, the expert's testimony must be supported by sufficient facts, as opposed to speculation. Martishius v. Carolco Studios, Inc., 142 N.C. App. 216 (2001). If the expert relies upon formulas or other testing to support his opinions, they must be reasonably relied upon by other experts in the field. Purdie, supra. Any reconstruction of the accident must occur under conditions similar to those that existed at the time of the accident. Jones v. Rochelle, 125 N.C. App. 82, 87-88 (1997); Addison v. Moss, 122 N.C. App. 569 (1996). Prior to December 1, 2006, experts in accident reconstruction in the State of North Carolina were prohibited from testifying as to their opinion on the speed of vehicles involved in accidents. Specifically, North Carolina law stated that: A witness who investigates but does not see a wreck may describe to the jury the signs, marks, and conditions he found at the scene, including damage to the vehicle...however, he cannot give an opinion as to its speed. The jury is just as well qualified as the witness to determine what inferences the facts will permit or require.


Shaw v. Sylvester, 253 N.C. 176, 180, 116 S.E.2d 351, 355 (1960). Since Shaw, many commentators, including some judges on the Court of Appeals, have expressed their frustration with the precedent set by Shaw. They continually urged the Supreme Court of North Carolina to review the issue of allowing such expert testimony as to the speed of vehicles in accidents based on the technological and scientific advancements now available to accident reconstructionists. In a sharply written opinion issued by the North Carolina Court of Appeals in Van Reypen v. Teeter, Justice McCullough adhered to the Shaw precedent, but in doing so criticized it severely. 175 N.C. App. 535, 624 S.E.2d 401 (2006). Referring to the Shaw precedent as "archaic," Justice McCullough urged the Supreme Court to "set aside a rule that no longer can be justified." Id., 175 N.C. App. at 542, 624 S.E.2d at 406. It appeared the Supreme Court would follow Justice McCullough's lead and do just that when they accepted the Van Reypen case for discretionary review; however, a short time later, the North Carolina Legislature enacted the Motor Vehicle Driver Protection Act of 2006 and the Supreme Court refused to review the case. N.C. Gen. Stat. §8C-1, Rule 702 (Editors Notes, 2006). The Motor Vehicle Driver Protection Act of 2006 went into effect on December 1, 2006. Id. The Act includes a significant addition to Rule 702 of the North Carolina Rules of Evidence concerning the testimony of experts. N.C. Gen. Stat. §8C-1, Rule 702 (2006). Specifically, subsection (i) was added to Rule 702, stating: A witness qualified as an expert in accident reconstruction who has performed a reconstruction of a crash, or has reviewed the report of investigation, with proper foundation may give an opinion as to the speed of a vehicle even if the witness did not observe the vehicle moving. Id. at § (i) (Emphasis added). It appears that the N.C. legislature realized the need for accident reconstruction experts to be able to give their opinion as to the estimated speed of the vehicles involved in accidents. The Editors Notes on the additions to the rule state that the new subsections will be applicable to "offenses" occurring on or after December 1, 2006. Although the term "offenses" typically suggests criminal application, Rule 702 has never been limited to criminal cases only. Therefore, it would follow that the application of these additions is not limited to criminal matters, but instead applies to civil proceedings as well. As such, experts should now be allowed to testify as to the speed of vehicles involved in accidents concerning both civil and criminal proceedings.


A. 1. 2. 3. GATHERING INFORMATION How does an accident reconstruction expert start to reconstruct an accident? How important is it to visit the scene of the accident? Could it be important to visit the scene around the same time of day?


[Information about traffic patterns, the flow of traffic, and any effect of the rising or setting sun can sometimes be critical.] 4. Is it important to talk to the drivers, eyewitnesses, or other observers? 5. You would agree that it is vital for any reconstruction expert to collect all of the available information and evidence before analyzing what happened? 6. When I took your deposition 6 months ago, you had formed your opinions about the cause of this accident, correct? 7. But prior to the deposition, you did not review the witness statement of _______? 8. And prior to the deposition, you did not interview or talk to the witness. 9. And you understand that this witness is the only independent witness who observed this accident from outside of either vehicle? B. PHYSICAL EVIDENCE AT THE SCENE

1. Have you examined the location where this accident occurred? 2. When did your examination of the scene occur? 3. Did you make our own measurements and tests? 4. If you used any instruments, did you confirm their correct calibration first? 5. If you conducted any tests, did you confirm that the conditions were substantially similar to the conditions present during this accident? 6. At the time of your examination, did you observe any physical evidence relating to this accident? 7. Plaintiff contends that the accident ... (for example, happened in her lane), doesn't she? 8. When you conducted an examination of the scene, there were no skid marks/tire prints from defendant's vehicle in the plaintiff's lane, were there? -also no ruts or gouges made by defendant's vehicle in her lane? 9. And you observed debris from this accident in both lanes and on both shoulders of the road, didn't you? 10. And there was no piece of physical evidence at the scene that conclusively established that the accident occurred in plaintiff's lane of travel. 11. In your experience in accident reconstruction, the investigating officer is usually in the best position to locate and identify physical evidence relating to the accident, isn't he? 12. And in your experience, the investigating officer will generally draw, on his diagram of the accident scene, any physical evidence relevant to the cause of the accident. 13. You have had multiple opportunities to review the accident report in this case, haven't you? 14. The report does not identify any physical evidence to support plaintiff's contention that the accident occurred in her lane, does it? 15. And you heard the investigating officer's testimony earlier today. He did not identify any such physical evidence, did he? [Through this line of questioning, you establish the lack of physical evidence at the scene to support the plaintiff's position. In the alternative, if your client reports that physical evidence


existed at the scene but the plaintiff's expert denies any supporting evidence, pursue the following line of questioning: * The expert did not examine the scene until several days or weeks after the accident. * Weather conditions can obscure, cover up or erase skid marks or other road markings. * Subsequent traffic can likewise obscure or cause confusing marks. * If the investigating officer noted physical evidence consistent with your client's position, establish that the officer is in the best position to observe and document physical findings immediately after an accident.] C. DIFFERENCE BETWEEN SKID MARKS AND YAW MARKS

1. Your report indicates ** feet of skid marks by the defendant's vehicle prior to the point of impact? 2. Skid marks are the marks left on a road surface when the tires slide? 3. And tires slide when the driver applies his brakes so hard that the tires/wheels lock up? 4. In this case, defendant's skid marks start in the curve and continue up to the point of impact, correct? [Keep in mind ­ the skid marks may "overlap", i.e., the investigating officer may start measuring the skid marks where the rear tires started skidding and he may end the measurement where the front tires stopped. This overlap "cheats" the driver by the length of his car's wheelbase. In some instances, it would be appropriate to reduce the length of skid marks by the vehicle's wheelbase as listed in the manufacturer's specs.] 5. Your investigation did not reveal any yaw marks by the defendant's vehicle? 6. Yaw marks are marks left on a road surface when the tires are also slipping sideways? 7. And in your experience, yaw marks in a curve such as the one traveled by defendant are some indication that the defendant's speed was too fast for the curve? 8. Did your investigation of the defendant's skid marks reveal any gaps in the skid marks? 9. In your experience, gaps in skid marks occur when the driver releases the brake pressure momentarily and the wheels start to roll again? 10. Based upon the absence of any gap in the skid marks, is it fair to say that defendant was continuously applying his brakes for ** feet prior to impact? [You can use the absence of yaw marks to counter the opposing party's contention that your client's speed traveling through a curve was excessive at or immediately prior to an accident. In addition, the characteristics of skid marks can reveal evasive action taken by a driver prior to an accident. In the event that brake failure is an issue, skid marks can also establish that the brakes were working at the time of the accident.]




Reaction times calculated by a reconstruction expert can sometimes be used to suggest the contributing negligence of the other driver or, conversely, the reasonable care of your own client. A long reaction time suggests that the driver was not paying attention immediately prior to the accident while an average reaction can suggest just the opposite. 1. According to your calculations, approximately 4 seconds elapsed before Mr. Jones reacted? 2. Generally, experts in your field use one second as the normal or average time for a person to perceive an event? 3. And generally, experts in your field use ¾ of a second as the normal or average reaction time after an event is perceived? 4. And there were no physical or medical conditions relevant to this driver that would account for a longer perception and reaction time, were there? [Alcohol consumption or the effects of medication can slow a person's reactions and increase his perception and reaction times. The following factors can also influence a driver's perception and reaction time: -age of driver; -driving experience; -training and skill, including whether the driver has a commercial drivers' license or has taken any driving classes; -state of mind (attentive, preoccupied, sleepy); -physical deficiencies (hearing, vision, night vision acuity and peripheral vision); -familiarity with the vehicle, road or surroundings; -knowledge of traffic laws.] 5. The time of day that this accident occurred did not influence the driver's reaction time, did it? [The glare from the rising or setting sun can sometimes influence perception.] 6. And there were no contributing weather conditions, were there? 7. And based upon the driver's testimony that he has driven this vehicle every day for more than a year, it is reasonable to conclude that the driver was familiar with the vehicle? E. IDENTITY OF DRIVER VS. PASSENGER

In some cases, there may be a dispute over who was operating the vehicle at the time of the accident. A reconstruction expert can utilize physical evidence at the scene, including the final resting place of individuals, to determine which party was driving. If this is an issue, you need to question the expert about:


-the damage to the exterior of the vehicle, including the location of damage, extent of damage, and direction of force; -damage to the interior of the vehicle. -the position of the individuals; -the injuries to the individuals. Sometimes, the location and nature of injuries can be matched with the interior damage of the vehicle. F. INSPECTION OF THE VEHICLES

1. You testified that you examined the physical damage to the vehicles to determine the speed and force of impact. Was your examination based upon your personal observation of the vehicles or did you have to rely on photographs? 2. Did you consider whether the vehicles incurred additional damage, after the accident, when they were removed from the scene of the accident? 3. How did you rule out any post-accident damage? 4. Did you consider whether either vehicle had any pre-existing damage prior to this accident? 5. Did you determine whether either vehicle had repair work as a result of a previous accident? 6. Did you consult with the vehicle's manufacturer or consult other sources to evaluate the damage? 7. Did you review any manufacturer or government crash tests on this vehicle model as part of your evaluation of the damage? 8. What variables or factors can influence the crash measurements that you took from each vehicle? G. STOPPING AT A STOP SIGN

Using physical evidence from the scene and physical damage to both vehicles, an accident reconstruction expert can calculate the speed at impact for both vehicles. If the issue is whether one driver stopped at a stop sign before entering a road, the expert can measure the distance from the stop sign to the point of impact. Factors that affect this measurement include whether the driver stopped even with the stop sign or at some point before or beyond the sign. Once the driver's acceleration factor is determined, it is possible to determine (mathematically) whether a driver could have stopped at the stop sign and still achieved his impact speed based upon the available distance from the sign to the point of impact. Consider the following line of questioning: 1. In your opinion, Mr. Jones stopped at the stop sign before pulling onto the highway. 2. And you base your opinion on calculations that it was possible for Mr. Jones to stop at the sign and still achieve his impact speed at the time of the accident. 3. Using the same calculations, it is also possible that Mr. Jones decreased his speed as he approached the stop sign, rolled through the stop sign and then accelerated enough to reach his impact speed at the time of this accident?


4. You cannot rule out this sequence of events, can you? 5. And, in fact, using mathematical calculations, there are a number of variables for the possible speed of Mr. Jones' vehicle as he rolled through the stop sign? 6. And if this scenario occurred, then Mr. Jones would not have stopped at the stop sign first? 7. And if this scenario occurred, then Mr. Jones would have rolled through the stop sign while attempting to look for on-coming traffic on the highway?


Accident reconstruction experts will often be asked to determine the initial speed of vehicles, the final speed or speed at impact, any acceleration or deceleration, distance and time traveled by vehicles. "Speed" is calculated in miles per hour. Reconstruction experts sometimes prefer to use "velocity". "Velocity" is the time rate of change of position of a body in a specified direction. Velocity is calculated in feet per second. To convert miles per hour into feet per second, multiply by 1.47. To convert feet per second into miles per hour, divide by 1.47. [There are 5280 feet in one mile and 3600 seconds in one hour. 60 miles per hour (mph) equal 88 feet per second (fps).] If the expert used equations to calculate speed, ask if his calculations are generally accepted as appropriate or accurate for making this determination. Also ask the expert if there are other calculations, which might be more favorable to your client, that are more appropriate or accurate to use. Commonly used abbreviations: a = acceleration d = distance f = drag factor g = gravity h = height m = slope, percent r = radius S = speed t = time, seconds V = velocity (feet per second) V i = initial velocity V e = end or final velocity


Commonly used equations: a = gf a = (V e - V i ) _________ t t = (V e - V i ) _________ a V i = V e ­ at V e = V i + at a = (V e ² - V i ²) _________ 2d V i = V e ² - 2ad V e = V i ² + 2ad d = V i t + at² 2 d = t (V i + V e) _________ 2 S = 5.47df Distance computed form initial velocity, end velocity, and time Speed (mph) of vehicle that slid to a stop Acceleration computed from initial velocity, end velocity and distance Initial velocity computed from end velocity, acceleration and distance End velocity computed from initial velocity, acceleration and distance Time computed from initial velocity, end velocity and acceleration Initial velocity computed from end velocity, acceleration and time End velocity computed from initial velocity, acceleration and time Acceleration computed from initial velocity, end velocity and time Acceleration computed from gravity and drag factor

Distance computed from initial velocity, acceleration and time

A number of factors can influence or affect speed calculations. When you examine or crossexamine an accident reconstruction expert, you should consider the following: Skid marks occur when the driver locks up his brakes. Therefore, it is conceivable that the driver applied his brakes for some undetermined distance before the brakes locked up and the skid marks appeared.




The driver may have decreased his speed by taking his foot off the gas pedal for some undetermined period of time before applying the brakes. The expert may not have taken into consideration the effect of different surfaces crossed by the driver, including pavement, dirt, or grass. In addition, the condition of these surfaces may not have been evaluated. Was the pavement wet or dry? Was the grass tall or short, thick or sparse? Was the ground under the grass hard or soft from recent rain? Did the expert examine the type and condition of the tires, and determine the amount of air pressure in the tires at the time of the accident.


Before you examine your reconstruction expert or cross-examine the opposing reconstruction expert, you should identify the weakest points of each expert's testimony, the strongest points or facts in your case, and a strategy for making these points during the expert's examination and/or cross-examination at trial. You should remember the following points each time you cross-examine any type of expert: Never ask the one question too many - save the "crowning" point for your closing argument, when the expert cannot argue with you or even respond. Do not try to work too many points into the cross-examination; success on 3-4 major points that can sway the jury will be more useful than "proving" your point on many little points that are irrelevant or unimportant to the final analysis.


1) Lexis' Forensic Accident Investigation (Bohan and Damask editors 1997)

Summary: This multi-volume work includes articles on low-speed, rear-end impacts, including bumper standards and designs; an analysis of air bags; determination of speed from crush measurements using an accepted computer program; and use of computer-generated reenactments. 2) 9 Am Jur Proof of Facts 3d 115, Reconstruction of Traffic Accidents (1990)

Summary: In addition to background information on some of the issues discussed above, the author includes sample interrogatories and deposition questions, and diagrams. 3) 4) 5) Expert testimony regarding the speed of a vehicle: The status of North Carolina law and the state of the art, 16 Campbell LR 191 (1994) Admissibility of computer-animated reenactments in federal courts, 30 Trial 9:78 (1994) Legislative Change in North Carolina Allows Expert Testimony Regarding Vehicle Speed in Transportation Cases, David M. Duke and Shannon S. Frankel, 16 The Defender, No. 1, 33-34, Summer 2007.





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