Motorcycle Accident Reconstruction: Lane-Splitting, Lane-Sharing, and Filtering in California

Motorcycle Accident Reconstruction: Lane-Splitting, Lane-Sharing, and Filtering in California

Lane-sharing is the practice by a motorcyclist of sharing a lane with another vehicle. Lane-splitting is the practice by a motorcyclist of riding between streams of traffic by riding on or near the striping between lanes. Filtering, which seems to be a term frequently used outside of the United States, is the practice by a motorcyclist of riding between lines of stopped or nearly stopped traffic at a traffic signal. The terms lane-splitting and lane-sharing are often used interchangeably and often the term lane-sharing is used as a catch-all term for all of these practices. These practices, which are allowed in California, allow a motorcyclist to drive faster than the surrounding traffic in congested or stop-and-go traffic [1, 2]. They also give motorcyclists more options for how they position themselves on the roadway, allowing them to “strategically place themselves in pockets of lower congestion during commute traffic” and to “distance themselves from safety hazards from larger vehicles beside or behind them, or from hazards presented by highly congested clusters of traffic” [2].

Motorcycle Accident Reconstruction: Applicable Error Rates for Struck Vehicle EDR-Reported Delta-V

Motorcycle Accident Reconstruction: Applicable Error Rates for Struck Vehicle EDR-Reported Delta-V

I’m in the midst of preparing 2 articles and a presentation for the upcoming EDR Summit in Houston (March 4-6, 2019). My topic is the use of struck vehicle EDR-data when reconstruction motorcycle-versus-passenger vehcile collisions. I thought I would put a teaser on the topic out into the world and also, hopefully, pass along some useful information. I’d love your thoughts on this topic. Read this post and then reach out to me at nrose@kineticorp.com or leave comments on the post. Thanks and I’ll see you in Houston!

Motorcycle Accident Reconstruction - Incorporating Struck Vehicle EDR Data

Motorcycle Accident Reconstruction - Incorporating Struck Vehicle EDR Data

This article describes the reconstruction of an intersection collision involving a motorcycle. EDR data from the sport utility vehicle that was struck by the motorcycle is incorporated into the reconstruction. This collision involved a motorcyclist riding a 2007 Harley-Davidson FLSTFI Fat Boy eastbound through the subject intersection. The driver of a westbound 2010 Ford Edge attempted to turn left to go southbound and the motorcycle struck the passenger’s side rear of the Ford. The driver of the Ford stated that she did not see the motorcycle prior to initiating her turn on a yellow traffic signal. A witness who observed the motorcycle prior to the collision stated that the motorcyclist accelerated into the intersection to make it through on the yellow light. The speed limit for east-west traffic through the intersection was 60 mph. An investigating officer noted that sun glare could have been a factor contributing to the Ford driver not seeing the motorcyclist.

Why Do Drivers Pull Out in Front of Motorcyclists? (Motorcycle Accident Reconstruction)

Why Do Drivers Pull Out in Front of Motorcyclists? (Motorcycle Accident Reconstruction)

In 1977, Hurt noted that “the most likely comment of an automobile driver involved in a traffic collision with a motorcycle is that he, or she, did not SEE the motorcycle…” Hurt continued: “The origin of this problem seems to be related to the element of conspicuity (or conspicuousness) of the motorcycle; in other words, how easy it is to see the motorcycle. When the motorcycle and the automobile are on collision paths, or when the vehicles are in opposing traffic, the conspicuity due to motion is very low, if it exists at all. Consequently, recognition of the motorcycle by the automobile driver will depend entirely upon the conspicuity due to contrast. If the approaching motorcycle and rider blend well with the background scene, and if the automobile driver has not developed improved visual search habits which include low-threat targets…the motorcycle will not be recognized as a vehicle and a traffic hazard exists” (emphasis added). But there is more to the story than that.

Determining Motorcycle Speed from the Struck Vehicle Translation and Rotation (Motorcycle Accident Reconstruction)

Determining Motorcycle Speed from the Struck Vehicle Translation and Rotation (Motorcycle Accident Reconstruction)

One indicator of a motorcycle’s impact speed with a passenger vehicle is the magnitude of the translation and rotation experienced by the passenger vehicle following the impact. Simulation can be an effective means to determine the motorcycle speed necessary to cause a specific magnitude of translation and rotation of the passenger vehicle. Deyerl and Cheng [2007, 2008] illustrated this type of analysis using EDSMAC4 simulation. Another software package that can be used to carry out such simulations is PC-Crash, a vehicular crash simulation software that is widely used by the reconstruction community. Numerous studies conducted over the last two decades have demonstrated that the impact and trajectory models of PC-Crash can accurately model vehicular crashes [Rose, 2018].

Equations for Estimating the Center of Gravity Height of a Motorcycle (Motorcycle Accident Reconstruction)

Equations for Estimating the Center of Gravity Height of a Motorcycle (Motorcycle Accident Reconstruction)

At times, an estimate of the center of gravity height of a motorcycle may be needed. For example, for a motorcycle crash that occurs on a curve, the center of gravity height may come into the calculation of the lean angle required for the motorcycle to follow a specific path through a curve. This analysis may play a role in determining why the motorcyclist crashed [Rose, 2014]. Cossalter [2006] presented equations for calculating the required lean angle of a motorcycle for a particular curve that take into account the width of the motorcycle tires. Carter [2015] and Rose [2018] validated Cossalter’s equations. These equations utilize an estimate of the combined center of gravity height of the motorcycle and rider, an estimate that will first require an estimate of the center of gravity height of the motorcycle without the rider. Foale [2006] has presented a method for calculating a combined motorcycle/rider center of gravity height once the center of gravity height of the motorcycle is known.

Conspicuity as a Factor in Motorcycle Accidents (Motorcycle Accident Reconstruction)

Conspicuity as a Factor in Motorcycle Accidents (Motorcycle Accident Reconstruction)

Researchers have often proposed that when a passenger car driver violates the right-of-way of a motorcyclist, the motorcycles lack of conspicuity is to blame (or is, at least, a contributing factor). In relationship to motorcycle conspicuity, Hurt noted that “the most likely comment of an automobile driver involved in a traffic collision with a motorcycle is that he, or she, did not SEE the motorcycle…” (emphasis in original). Hurt continued: “The origin of this problem seems to be related to the element of conspicuity (or conspicuousness) of the motorcycle; in other words, how easy it is to see the motorcycle. When the motorcycle and the automobile are on collision paths, or when the vehicles are in opposing traffic, the conspicuity due to motion is very low, if it exists at all. Consequently, recognition of the motorcycle by the automobile driver will depend entirely upon the conspicuity due to contrast. If the approaching motorcycle and rider blend well with the background scene, and if the automobile driver has not developed improved visual search habits which include low-threat targets (such as motorcycles and bicycles, as contrasted with the high-threat targets presented by trucks and busses) the motorcycle will not be recognized as a vehicle and a traffic hazard exists.” Without discounting the factors listed by Hurt, it should also be recognized that his statements go too far, discount too much, and are not fully supported by later research. Though he acknowledges it elsewhere, physical obstructions from other traffic, inattention and distraction on the part of a passenger car driver, and lack of expectation to encounter a motorcycle are other factors that may account for a driver not seeing a motorcyclist.

My Two Cents on Writing Accident Reconstruction Reports in a Legal Setting

My Two Cents on Writing Accident Reconstruction Reports in a Legal Setting

When you write a report, try to disprove your own opinions. Philosopher of Science, Karl Popper wrote that “whenever we propose a solution to a problem, we ought to try as hard as we can to overthrow our solution, rather than defend it. Few of us, unfortunately, practice this precept; but other people, fortunately, will supply the criticism for us if we fail to supply it ourselves. Yet criticism will be fruitful only if we state our problem as clearly as we can and put our solution in a sufficiently definite form – a form in which it can be critically discussed.” Adopting this type of approach will make you a better accident reconstructionists and a better witness.

Sliding and Tumbling Deceleration of a Motorcycle (Motorcycle Accident Reconstruction)

Sliding and Tumbling Deceleration of a Motorcycle (Motorcycle Accident Reconstruction)

A quick aside...this is a draft of another section from the motorcycle accident reconstruction book that I'm writing with Lou Peck and William Neale. Lou, in particular, assisted with this section. Let me know what suggestions you have for making this more readable and useful. Thanks!