Accident Reconstruction Essentials Attorneys Should Be Aware ofWhen Litigating Motorcycle Crash Cases
This post is a companion to a continuing education course that I developed for attorneys who litigate cases involving motorcycle crashes. In some ways, motorcycle crashes are like any other crash, and attorneys litigating car crash cases will already have a sense for where to focus their energy and attention when they encounter a motorcycle crash. However, there are some unique elements of motorcycle crashes that attorneys will benefit from keeping in mind. This post covers some of those unique items. If you find this material useful or interesting, consider having me present these essentials, with case studies for each, at your law firm. We will go through the process of getting the presentation approved for CLE credits in your local state. Reach out to me at nrose@explico.com.
Essentials of Motorcycle Accident Reconstruction
1. Tires, tires, tires…inspect the tires of the motorcycle.
This is a common element of motorcycle accident reconstruction that I see neglected. For any type of crash, physically inspecting the involved vehicles can produce useful data for a reconstruction. When the vehicle is a motorcycle, a centerpiece of the inspection should be a detailed examination of the tires. This examination can lead us to an understanding of the rider’s braking actions preceding the collision. Heavy braking on a motorcycle will sometimes produce skidding, and skidding can produce a tire mark on the roadway. When this tire mark is deposited on the roadway, tire damage often results (longitudinal abrasions, scuffing, or a flat spot). Thus, finding skid-related damage to a motorcycle tire can tell us which tire of the motorcycle deposited the skid mark. So, when possible, ensure that the motorcycle is preserved and available for inspection.
As an example, Explico inspected a motorcycle for which there was an allegation of a defective front brake component that would prevent effective use of the front brake. However, longitudinal abrasions on the front tire – and connecting those abrasions to a specific tire mark on the road surface – demonstrated that the front brake system was functioning at the time of the crash. If the front brake system had not been functioning, then the front tire would not have been able to deposit a skid mark. As another example, the photograph below depicts the rear tire of a motorcycle that exhibits a circular area of abrasions from heavy braking with the rear brake. Chapter 5 in my book Motorcycle Accident Reconstruction includes further discussion of evidence on tires and roadways and what we can learn from that evidence.
2. There’s more to that GoPro video than meets the eye.
Sometimes there is speed data contained in the metadata of GoPro camera footage. Have your expert check the video footage for this data. As an example, Explico reconstructed a nighttime motorcycle crash involving a newer model Chevrolet and a Suzuki motorcycle. The Chevrolet turned left into the path of the Suzuki. Investigating officers located a GoPro camera at the scene, which had initially been attached to the motorcyclist’s helmet. Investigating officers obtained video of the crash from the GoPro camera. There was more to this footage than the officers realized. We determined that the footage was captured on a GoPro Hero7 Silver. Some GoPro camera models, including the Hero7 Silver, capture telemetry data along with the video, including the camera’s location, path, speed, and acceleration. We used a telemetry extractor to extract the raw telemetry data from the GoPro video file. This data showed that the motorcyclist was speeding significantly in the moments leading up to the collision. The data demonstrated that, had the motorcyclist not been speeding, the left turning vehicle would have been able to complete its turn without a collision occurring. Of course, it could have shown the opposite - that the motorcyclist was not speeding and that the left turning vehicle could not have cleared. Speed data from GoPro footage is similar to event data from a vehicle’s airbag control module - it is objective data for the crash that can give both sides in a legal case a baseline snapshot of what occurred. A peer-reviewed technical paper published by the Society of Automotive Engineers titled “Validation of Telemetry Data Acquisition Using GoPro Cameras” describes the process of obtaining this data from the video footage and validates the accuracy of the data.
3. The crash was probably captured on video.
Even if a motorcyclist was not wearing a GoPro camera, there is still a possibility the crash was captured by a camera. We now live, and reconstruct car crashes, in a surveillance society. Gone is the time when accident reconstruction was focused purely on physical evidence and mechanical phenomenon – tire marks, gouges, vehicle deformation, broken glass, and the like. Few crashes occur anymore without also leaving a trail of electronic data or video evidence from an event data recorder (EDR) or a surveillance camera. For a crash location, examine surrounding businesses or homes for the possibility that there is a surveillance camera that could have captured the crash. Investigating officers are more and more aware of this and are often examining the area surrounding the scene for cameras. A second set of eyes on it doesn’t hurt, though. Chapter 5 in my book Motorcycle Accident Reconstruction includes extensive discussion of video analysis methods and a case study with a reconstruction of a motorcycle crash that was captured on video.
4. There’s data on the struck vehicle that will tell us the speed of the motorcycle (and a whole lot more).
Most modern passenger vehicles are equipped with an event data recorder (EDR) contained in the airbag control module (ACM). The ACM is the unit that decides if and when to deploy the airbags. A common motorcycle crash scenario occurs when a passenger vehicle equipped with an EDR turns left across the path of a motorcycle and a collision occurs. The EDR data on the passenger vehicle will often include pre-collision speed, throttle, brake, and steering data for 5-seconds preceding the collision. This data can be used to establish the specific characteristics of the left turn. In addition, the EDR data often reports the change in velocity experienced by the passenger vehicle during the collision. This change in velocity can often be used to calculate the change in velocity experienced by the motorcycle. This, in turn, can be used to calculate the motorcycle’s impact speed. Whenever possible, ensure that the struck vehicle is preserved, so that this data can be accessed from the vehicle. Chapter 9 in my book Motorcycle Accident Reconstruction describes validated, peer-reviewed, and industry accepted methods for evaluating the EDR data from passenger vehicles and using it to calculate the speed of the motorcycle.
5. It took a lot of speed to spin that vehicle.
When a motorcyclist strikes a passenger vehicle on the side and behind the front seats, significant post-collision rotation of the passenger vehicle can occur. This rotation is piece of evidence that can be used to determine the impact speed of the motorcycle. All other variables held constant, the higher the speed of the motorcycle, the higher the magnitude of rotation the struck vehicle will experience. Thus, the amount of rotation experienced by the struck vehicle can be used for a quick back-of-the-envelope speed assessment for the motorcycle. The amount of spin experienced by a struck vehicle can usually be determined from the intersection geometry and photographs taken by investigating officers at the crash scene. There is an important caveat, though: As my published research has shown, the speed of the struck vehicle also significantly influences that vehicle’s rotation (not just the speed of the motorcycle). The higher the speed of the struck vehicle, the more rotation will occur. Also, the further back on the vehicle the motorcycle impacts, the more rotation will occur.
As an example of an instance where significant struck vehicle rotation did indicate a high motorcycle speed, the video below depicts a reconstruction of a crash where a motorcyclist collided with the driver’s side rear of a minivan. Using physics based simulation, I determined that a motorcycle impact speed of 80 mph was necessary to cause the rotation of the minivan. In this case, there was also substantial deformation to both the van and the motorcycle, and there was event data from the airbag control module on the van. These other pieces of evidence also substantiated a high speed for the motorcycle. The calculated speed of the motorcycle for any particular crash will, of course, depend on the specifics of the evidence from that crash. Chapter 8 in my book Motorcycle Accident Reconstruction describes validated, peer-reviewed, and industry accepted methods for conducting this analysis.
6. Consider which portion of the struck vehicle was contacted.
When evaluating a crash where a driver turned their vehicle into the path of a motorcycle, it can be helpful to examine which portion of the vehicle was struck. Again, a lot of factors come into play, but consider the difference between the motorcyclist striking the front of the turning vehicle versus the rear. The motorcyclist who struck the front likely had less time available to avoid than the motorcyclist that struck the rear. If a motorcyclist strikes the very rear of the vehicle, then it’s possible that a small change in the speed of the motorcycle would have led to the crash being avoided. As with all of these points, this has to be taken on a case by case basis, and the details of any particular crash will matter. But, as a quick assessment tool for your case, it can be useful examine what portion of the left turning vehicle was struck. Chapter 10 in my book Motorcycle Accident Reconstruction discusses how to evaluate the time available for a motorcyclist to avoid a collision.
7. Kawasaki motorcycles have event data recorders (EDRs).
EDRs that record crash-related data are currently installed on few motorcycles. However, many Kawasaki motorcycles now include crash-sensing EDRs. The owner’s manual for the motorcycle will typically specify whether a motorcycle is equipped with an EDR. For Kawasaki’s equipped with EDRs, events are triggered to be recorded by a combination of heavy braking (0.6g or greater) and a tip-over of the motorcycle. The EDR data includes vehicle speed, throttle position, engine RPM, gear position, and clutch in/out. Another reason to ensure that the motorcycle gets preserved for inspection!
8. Other motorcycles might have some form of electronic data.
Some Can-Am motorcycles and ATVs include EDRs that report “last instant” data, including in some instances 60 seconds of vehicle speed, engine speed, throttle position, and much more. The infotainment systems on some Harley-Davidson motorcycles will record speed and route data, if the system is being used for navigation. Some newer Ducati motorcycles have EDRs. Have your expert check the particular make and model motorcycle to determine if it contains an EDR.
9. That Toyota Corolla can out-brake that motorcyclist.
Expert motorcycle riders may be able to achieve decelerations approaching or exceeding 1g under emergency braking on a modern motorcycle, a level that is comparable to what many modern passenger vehicles can achieve. Most riders, though, will not be able to fully utilize the braking capabilities of their motorcycle, or to achieve the level of deceleration that expert riders can. This is, in part, because of the complex brake actuation and modulation required by a rider as the weight of the motorcycle shifts to the front during heavy braking. The rider needs to roll off the throttle and simultaneously apply both the front and rear brakes, which on most motorcycles are controlled independently. The front brake is controlled with a lever on the right handlebar, and the rear brake is controlled with the foot pedal on the right. When weight shifts towards the front of the motorcycle as the braking builds up, the rider needs to apply more front brake pressure and reduce the rear brake pressure. This modulation maximizes the deceleration generated by the front brake and prevents lockup and lifting of the rear wheel and tire. If the rider does end up locking the front wheel during braking, the motorcycle becomes very unstable and they will need to react quickly, releasing the brake and starting their brake modulation again. This is another reason most riders do not achieve the highest possible deceleration under emergency braking. They hold back on their braking, in order to avoid creating instability and capsizing the motorcycle.
Similarly, many passenger car drivers also hold back and do not fully utilize the braking capabilities of their vehicles. That said, there is no danger of instability in fully applying the brakes of a passenger vehicle. If a passenger car driver chooses to fully apply the brakes of their vehicle, they are likely to succeed at producing a high level of deceleration, at or near the full capability of the vehicle. Motorcyclists, on the other hand, are usually not capable of fully utilizing the capabilities of their motorcycle, even if they decided to try. A driver who fully applies the brakes on a modern vehicle with antilock brakes will produce decelerations in the 0.9g to 1.1g range. Average motorcyclists who attempt to maximize their deceleration under heavy braking will likely produce decelerations in the range of 0.5g to 0.8g. Chapter 3 in my book Motorcycle Accident Reconstruction describes the braking capabilities of motorcyclists based on peer-reviewed, technical literature. The following image is Table 3.2 from the book, summarizing the best effort decelerations produced by motorcyclists in twelve technical articles that reported testing with motorcyclists.
10. Consider the speedometer.
Sometimes after a collision, a motorcycle’s speedometer or tachometer will be stuck with a residual reading other than zero. I have seen this most frequently with the speedometers of newer-model Harley-Davidson motorcycles. In some instances, the characteristics of the speedometer or other physical evidence will make it evident that the residual speed reading is not a reliable indicator of the motorcycle’s impact speed. However, if the motorcycle is equipped with a speedometer with a stepper motor, then the speed reading on the speedometer just might be an accurate speed. A stepper motor requires continuous electrical power to adjust the speedometer reading either upward or downward. If a power loss occurs during the collision, there is no way to generate the stepper motor movement needed to return the needle to its zero position. A needle attached to an unpowered stepper motor will remain in its position indefinitely. Yet another reason to make sure the motorcycle gets preserved, although this can sometimes be seen in photographs from the scene, as well. Chapter 9 in my book Motorcycle Accident Reconstruction includes discussion of the technical literature on motorcycle speedometers - which speedometers are likely to freeze with a power loss and how to evaluate this evidence in relationship to the collision. Also, this blog post is relevant.
11. Motorcycles are easy to miss, especially when they are behind a big truck.
Attorneys on both sides of the aisle (so to speak) sometimes adopt a simplistic view of why a driver might miss the presence of a motorcycle. In truth, this is a complicated issue with many twists and turns. However, an important physical explanation for why a driver might not see a motorcyclist is sometimes neglected. Motorcycles are often narrower than other vehicles, and thus, foliage, signage, power poles, bridge columns, and other vehicles can sometimes physically obstruct the visibility of a motorcycle. The presence of other traffic is a big deal here. Typically, in a reconstruction, there will not be physical evidence of where other traffic was located, so it falls to the attorneys to flesh that out in the testimony of the involved drivers and witnesses. Of course, if there is video of the crash, it could show the locations of other traffic that might have obstructed the motorcyclist. In addition, once the locations of other traffic has been established, we can recognize that a motorcyclist can occupy different positions within a lane, and these positions can influence both the motorcyclist’s ability to see other traffic and the ability of other drivers to see the motorcyclist within that traffic. Sometimes the evidence will show that a motorcyclist was physically obstructed; other times it will show that they were not. When a motorcyclist is there to be seen (not obstructed), but is still is not detected, this could be due to inattention or distraction on the part of the driver, to the driver not expecting to see a motorcyclist on the road, or to a lack of conspicuity of the motorcycle and rider. Sometimes, a driver detects an approaching motorcyclist, but still pulls into the motorcyclist’s path. In these instances, the driver may have misjudged the speed of the motorcyclist and its distance from the intersection. This all has to be evaluated on a case by case basis. But it also leads to the importance of gathering info about surrounding traffic in the area of the crash.
12. Consider the visor.
Motorcycle helmets are usually equipped with visors. Some visors are tinted and these are not intended to be worn while riding at night. If a motorcyclist was wearing a tinted visor at night, this could explain why they didn’t see something that was there to be seen – a curb, a pothole, or another vehicle. This points to the importance of ensuring preservation of the motorcyclist’s gear, in addition to the motorcycle itself.
Photo by Jusdevoyage on Unsplash