The Importance of Accident Reconstruction in Personal Injury Lawsuits

The Importance of Accident Reconstruction in Personal Injury Lawsuits

Written By: Nick Todorovic and Keanin Parish, Student-at-Law

A motor vehicle accident can be a traumatic experience for all involved. In some cases, the issue of who is at fault for the motor vehicle accident can be in dispute. In those cases, accident reconstruction experts are retained to help understand what actually happened.

Accident reconstruction is the process of investigating, analyzing, and drawing conclusions based on the evidence surrounding a motor vehicle accident. It requires the expertise of engineers who use their knowledge to reverse engineer how the motor vehicle accident took place. The products of these investigations may produce answers about time, speed, distance and force of the vehicles involved in a motor vehicle collision.  It can be a complex process, in part because no two collisions are the same.  For that reason, accident reconstruction requires technicians whose knowledge is more specialized than that of judges.  In Clarke v Toronto Transit Commission, 2018 ONSC 6453, Justice Koehnen sheds light on the need for accident reconstructionists:

Judges are not accident reconstructions experts. While I may be numerate, my math skills, like those of the majority of lawyers and judges I have encountered, are not particularly sophisticated. I cannot perform or assess, on my own, complex mathematical calculations such as, for example, those required to calculate the difference that a rounded or square corner of a car would have on its speed. Whatever understanding I would derive from reading about complex mathematical calculations in an expert’s report would be haphazard.

Accident reconstruction involves visiting the scene of the collision and investigating the vehicles that were involved in the collision. This involves collecting evidence, such as videos of the collision, taking photographs, taking measurements, downloading the event data recorder, and hearing eyewitness testimony.  One example of evidence at the scene of a motor vehicle accident could be tire marks on the road or lack thereof, which can shed light on who braked and when. RCMP officer Sgt. Ryan Case summarizes the importance of tire marks here:

The number one thing that we’re really interested in is tire marks.  Pre-collision tire marks are very helpful because they show direction of travel and where the vehicles were placed on the roadway prior to colliding with each other.  That’s important because they’ll help determine which driver caused the collision in the first place.  Post-collision tire marks will show exactly where the vehicle travelled.  After colliding with each other and disengaging from each other, they travel to their final rest position.  And those tire marks will show exactly where the vehicle travelled.  And those tire marks are critical in order for us to conduct a speed calculation.  Looking at those tire marks, we have to determine whether or not they were created by a braking tire, so a tire that has locked up while skidding, and whether or not those tire marks were created by conventional braking, which every vehicle has, or if they are created by ABS tires.  By determining that, it affects the speed calculation.

Typically, accident reconstruction experts are called as expert witnesses to testify in personal injury cases – the testimony of which can be a vital in helping determine who is at fault.  Take, for example, the case of Coulter (Guardian ad litem of) v. Ball, 2005 BCCA 199, 2005.

In Coulter, the plaintiff Jason Coulter claimed for damages for personal injuries suffered as a result of a motor vehicle accident. On February 10, 1997, Mr. Coulter was a passenger in a vehicle driven by the defendant, Erin Ball, when it collided with a second vehicle driven by the defendant, Pierre Leduc. As a result, Mr. Coulter was found to have suffered a brain injury. One question before the court was whether the defendant, Pierre Leduc, was speeding at the time of the collision.

To answer this question, the trial judge considered the reconstruction analysis of an accident reconstruction expert:

Both the plaintiff and Erin Ball rely upon the reconstruction analysis submitted by D. Harvey West. Mr. West performed a momentum calculation that predicted the speed, at impact, of the Ball vehicle as between 29 and 37 kilometres per hour, consistent with Ms. Ball’s testimony. However, the analysis predicts [sic] an approach speed for the Leduc vehicle at between 78 and 85 kilometres per hour, considerably in excess of both the posted limit and the testimony of Constable Leduc.

After considering Mr. West’s reports regarding speed of vehicles, the trial judge then reviewed the analysis about the amount of time the vehicles would have required to avoid an accident:

Mr. West calculated that the Ball vehicle or its headlights would have been visible to Constable Leduc for 5.4 to 6.2 seconds after it left its stopped position. He estimated that the truck would have obstructed the vehicle’s view for a period of less than 1.7 seconds. On this calculation there was a time of unobstructed view of between 3.7 and 4.5 seconds, ample time to observe the peril and react in sufficient time to avoid the collision.  In short, on Mr. West’s calculations, assuming a proper lookout, there was time for Constable Leduc to apprehend the danger, to react, and to avoid the collision.

These reports allowed the trial judge to make multiple key findings of fact, such as, Mr. Leduc was both speeding in excess of the posted speed limit and that he had enough time to react to the plaintiff’s vehicle to avoid the collision. As a result, the trial judge concluded that the defendant, Pierre Leduc, was at fault for the motor vehicle accident.


Accident reconstruction experts are an important element in determining the nature of an accident.  Through their investigations, accident reconstruction engineers can provide answers about the cause of a collision and, in turn, strengthen the evidence of a personal injury lawsuit borne out of one.  To provide the best possible results for our clients, the lawyers at McLeish Orlando regularly work with experienced accident reconstruction experts.  If you have been injured in a motor vehicle collision, please contact our team.

Nick Todorovic


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