MAKING ACCIDENT RECONSTRUCTION WORK FOR YOU
By William L. Larson, Esq.

Virtually every automobile accident case you handle will involve, at a minimum, basic accident reconstruction. Your client has suffered personal injuries and other damages, and one of your first questions to the client is, "How did the accident happen?" As the client relates the story, issues of liability and proof naturally arise. The purpose of this article is to help introduce concepts of accident reconstruction and analysis helpful in proving and developing facts and opinions in automobile accident litigation.

The Basics: Time, Distance, Speed

The most basic and important concepts in all of accident reconstruction are time, distance and speed. These concepts provide the underpinnings from which virtually all accident reconstruction proceeds. Therefore, you must have a substantial understanding of the interrelationship between these three concepts in order to understand how most automobile accidents occur.

It is fairly easy to understand that an automobile traveling at a fixed rate of speed for a certain period of time will cover an ascertainable distance. Or, stated another way, an automobile traveling at a fixed rate of speed will take a determinable period of time to travel a state distance. The difficulty arises when you must precisely, conveniently and readily quantify these calculations.

The simplest approach to this problem is to take the speed of a vehicle in miles per hour (mph) and multiply it by a factor of 1.5 to obtain the approximate number of feat per second the vehicle is traveling. For example, a vehicle traveling 20 mph is traveling approximately 30 feet per second (20 x 1.5 = 30). therefore, if the same vehicle traveled at 20 mph for 4 seconds, it will have traveled approximately 120 feet (20 x 1.5 x 4 = 120). As indicated, the factor of 1.5 is an approximation. The precise conversion factor is 1.46666 (with the number 6 running indefinitely). If precision is key to our case, you may want to use a factor of 1.467 to obtain a result that is within a few inches of the exact distance traveled.

A fair question at this point is, "Why do I care about all this?" The reason is that most contested liability cases will be, to a great extent, dependent upon the accuracy and believability of your client's testimony vis-à-vis the opposing party's testimony regarding time, distance and speed. Accordingly, it is incumbent upon you to engage in a basic reconstruction of the accident to determine whether your client's story makes sense and to fully understand the areas of attack from and inquiry for the other side. Further, a clear understanding of the time, distance and speed relationships in a particular accident will be critical in preparing, evaluating and deposing independent witnesses.

In a case my firm handled several years ago, a seemingly solid independent witness for the plaintiff was strongly discredited at trial because the time, distance and speed testimony he provided was inconsistent, subjecting it to attack and impeachment by the defense and the defense experts. The implication was that the witness could not have seen what he testified he saw; as a result, his credibility was questioned significantly.

Utilizing the Basics to Prepare Your Client

Your case obviously begins with your client. Assuming that your client was riving a vehicle at the time of the accident, it is imperative that your client provide very specific and detailed testimony regarding how the accident occurred. This testimony by your client should, ideally, provide time, distance and speed testimony that makes sense and is accurate. Before your client's deposition, then, your client must be fully prepared on the basics of accident reconstruction -- time, distance and speed.

In each case, there will be specific and easily identifiable points in time which inevitably will arise during the deposition. Common examples of this are questions such as: "When did your client first see the traffic light? When did your client first see the other vehicle? When did your client first hear the honking of the horn?" Your job in preparing your client for testimony is to identify these obvious points in time and begin to prepare a complete time, distance and speed analysis of the accident.

In my experience, the client usually can provide fairly accurate and reliable testimony regarding his or her vehicle's speed. The tricky parts come with the concepts of time and distance. To teach my clients about the concept of time, I usually have them close their eyes and visualize a precise moment in time. Then I ask them to picture themselves driving down the road just before the critical event occurs as I slowly count off the seconds. When my clients tell me the event occurred, I stop counting and the number at which I stop is the time estimate. For example, if I ask a client, "From the point in time at which you first saw the traffic light change to green until you entered the intersection, how much time elapsed?", I will establish my client's speed at the time the light turned green, then I will count off the seconds as my client visualizes traveling from that point in time until he or she entered the intersection. By utilizing this technique, I consistently am able to achieve valid and reliable time estimates from my clients.

It has been my experience that the concept of distance causes clients the most trouble. People simply do not appreciate how much distance they travel over a short period of time in an automobile. In order to surmount this problem, I usually explain very carefully the conversion factor I discussed above. In other words, I tell my clients that they travel a factor of 1.5 times the speed of their vehicle in miles per hour to determine the number of feet per second they travel. Most clients are able to grasp this concept fairly quickly and are able to do the requisite mathematics to calculate what distance they traveled over a stated period of time. Nothing will harm a case more quickly than a client who testifies that he was 50 feet away from something and it took 4 seconds at 30 mph to get there.
Do not let this happen in your cases.

As a practical mater, I carefully prepare my clients first on speed and second on time. Then I will educate them on how to extrapolate the proper distances. their estimates then make sense and have validity. A significant consequence of preparing your clients in this manner will be that your clients' testimony will provide a solid foundation for a professional reconstruction of the accident (should that be necessary), and your clients' testimony will not be capable of easy impeachment.

An additional benefit of thoroughly preparing your client on the basics is that your clients will become sophisticated witnesses who will perform much better at arbitration or trial. It has been my experience that having my clients firmly grounded in these basic concepts of accident reconstruction creates a certain savvy and intelligence in them which makes them much better witnesses. I recall a situation from an arbitration I did a couple of years ago in which the arbitrator, an experienced defense attorney, asked my client, "from the time you first saw the blue car and you were traveling 30 mph until the time that you entered the intersection, how much time elapsed?" My client thought long and hard for a moment and said, "Two seconds." The arbitrator then asked, "When you first saw the blue car how far away from the intersection were you?" My client thought for a moment and said, "Approximately 80 to 100 feet." I had specifically prepared my client on these various questions. The arbitrator was satisfied with my client's responses, and it resulted in my client not only prevailing in the arbitration, but also receiving a very favorable award. This result may be contrasted with those situations we have all seen where a particular party is not well prepared in these concepts and provides wholly unreasonable and ridiculous testimony. The result is a direct hit to that party's credibility that will bleed over into all parts of his or her testimony.

Utilizing the Basics to Depose the Opposing Party

As discussed above, precise and accurate testimony with respect to time, distance and speed is the most valuable testimony a party an give regarding how an automobile accident occurred. Therefore, the best way to impeach an opposing party is t ask very precise and relevant questions regarding the time, distance and speed aspects of the accident in question. Your questions must be targeted to elicit this type of testimony at various logical points in the accident scenario. I typically begin with an early and convenient point in the automobile trip of the person being questioned and proceed through each logical sequence of events specifically establishing the time, distance and speed information for each period. In my experience a great many opposing parties are not well prepared on these concepts and provide easy targets for attack and impeachment. The fact of the matter is, if the accident is a close call on liability and your client provides accurate and consistent testimony with respect to the concepts of time, distance and speed, and the other side does not, a professional reconstruction of the accident will almost always favor your client.

My firm handled a motorcycle accident case a few years ago in which we represented the motorcycle driver. We thoroughly prepared him for his deposition, and he provided very good testimony relative to how the accident occurred. When we deposed the defendant, his testimony was not nearly as good. We then hired an accident reconstructionist who reconstructed the accident based, for the most part, on our client's testimony and the consistency between that testimony and the physical evidence found at the accident scene. Later in the case when we designated our experts, the defense designated an accident reconstructionist whom they subsequently withdrew just before that expert's deposition. The case settled for a substantial amount of money shortly thereafter. I am convinced that the thorough preparation of the client and the failure of the defendant to provide useful testimony resulted in resolution of the case in our client's favor.

Beyond the Basics: Skid Marks, Debris and Deformation

A significant automobile accident will often include skid marks from one or both vehicles, numerous debris deposited on the roadway, and significant denting and deformation of the bodies of one or both vehicles. Many accident reconstructionists now utilize sophisticated computer programs which use virtually all of the available information and data pertaining to the accident to perform a computerized reconstruction of the accident. Utilization of type and location of debris and a quantification of the deformation of the vehicle provides critical data for these and other types of accident reconstructions. In a serious accident, the traffic accident investigation report is often very detailed and provides precise cataloging and measurement of accident debris. It is also routine in serious accidents for the investigating law enforcement agency to take extensive photographs of the accident scene. It is obvious, then, that a critical aspect of your duties as an attorney in these situations is to lay a proper foundation for the various measurements and data contained in the accident investigation report and to obtain all photographs taken at the accident scene. In serious cases it also would behoove you to send a very experienced investigator, or go yourself, to take numerous photographs and measurements of the accident scene. The professional reconstructionist can then use the data concerning debris and vehicle deformation to engage in a more precise accident reconstruction. Investigating officers frequently utilize a roll-a-tape to measure pre-impact and, sometimes, post-impact skid marks. It has been my experience that locked wheel skids often terminate at the point of impact in an accident. It has also been my experience that investigating officers frequently use pre-impact skids to calculate the pre-impact speed of the skidding vehicle. If this occurs, it is important that you understand how, on a basic level, to calculate a vehicle's speed from skid marks. However, please be aware that whatever value you obtain will often understate the actual speed of the vehicle, since the vehicle came to a stop by virtue of a significant impact with another vehicle (i.e., the skidding vehicle would have continued to skid beyond the point of impact if the accident had not occurred.

The formula for determining the speed of a vehicle from its locked wheel skids on dry, level pavement is to multiply the length of the skid by a constant of 30 by the applicable coefficient of friction and then taking the square root of the resulting product (a product is the result of multiplying things together). The usual coefficient of friction for a typical passenger vehicle on dry, level pavement is .70 or .75. Thus, for example, assume that the opposing party's vehicle laid down 106 feet of 4 wheel, locked wheel skids on dry, level pavement which is in good condition. You would calculate that vehicle's speed based on the 106 feet of skid marks as follows: 106 x 30 x .75 = 2385. The square root of 2385 is 48.8. Based on the skid marks, you have determined the opposing party's vehicle had a pre-skid speed of 48.8 mph.

To show you how the foregoing skid mark analysis can be helpful, I recently settled a case in which I represented a rear seat passenger in a BMW automobile that made a left turn in front of a 1969 Mustang. There was no doubt that the driver of the BMW was primarily at fault for the accident. My client suffered a fractured vertebra and had some ongoing residual problems. I settled with the driver of the BMW and set my sights on the driver and owner of the 1969 Mustang. My review of the police report indicated that the Mustang laid down 131 feet of locked wheel skids which terminated in a tremendous broadside impact between the two vehicles. The investigating officer opined that at the time of the accident the Mustang was traveling approximately fifty-five to sixty miles per hour in a forty mile per hour speed zone. When I took this officer's deposition, he indicated that his opinion that the Mustang was traveling fifty-five to sixty miles per hour was based solely on the 131 feet of locked wheel skids. I did the skid mark calculations myself and determined that the Mustang was traveling between fifty-two and fifty-six miles per hour utilizing coefficient of frictions of .70, .75 and .80. The most important information elicited from the officer's deposition was that, since the skid marks terminated in a very significant impact between the two vehicles, it was obvious that the fifty-five to sixty miles per hour speed estimate grossly understated the speed of the Mustang. Other evidence indicated that the Mustang suffered incredible front-end damage, and the BMW sustained substantial right-side body damage. My accident reconstructionist estimated that the Mustang was traveling between seventy-five and eighty miles per hour immediately before its brakes were applied. Therefore, at the moment its brakes were applied, the Mustang was traveling approximately double the speed limit.

This example illustrates several points I have been trying to make in this section. By being familiar with skid mark analysis I was able to demonstrate, based upon the skid marks alone, that the Mustang was greatly exceeding the speed limit. Further, since the skid marks terminated in a very significant collision, it is clear that the Mustang was traveling at a high rate of speed when the skid marks terminated. By obtaining photographs of both vehicles, I was able to present this information to my expert who was able to conduct a deformation analysis of the vehicles and determine the extreme speed of the Mustang. After the deposition of the police officer, I presented this information in a very detailed letter to counsel for the driver and owner of the Mustang. Within two weeks of my letter, I was able to bring approximately one and one-half years of litigation to a close with a very favorable settlement for my client.

Conclusion

A basic, working knowledge of elementary accident reconstruction principles will yield great benefits in automobile accident litigation. It is only with a reasonable understanding of these concepts that you can understand how many automobile accidents occur. Without a firm understanding of how an accident occurred, you would be at a loss to evaluate adequately your client's liability position. Without an adequate evaluation of liability, your case is likely to be protracted and resolution difficult.

It is my hope that this article has helped you understand and appreciate some of the basic accident reconstruction principles.