Reverse Engineering the Crash that Never Happened

James R. Schmidt, Jr., BSME, Collision Reconstruction Engineering Analyst

He was on a routine drive home just before midnight on a Saturday night. Traveling westbound, he stopped at a red light at a T-intersection. The light changed to yellow … one-one thousand, two-one thousand, three-one thousand, four-one thousand, then to red for the roadway running north/south, at which he was stopped … one-one thousand, two-one thousand… Then, the light changed to green, and he proceeded into the intersection to turn left. One-one thousand, two-one thousand, three-one thousand, four-one th… From his left, a speeding car ran the red light, and plowed his vehicle on the driver’s side. That can’t be good, can it? Miraculously, he survived, without a scratch. How do I know? How is this possible?

Well, I am the “he” that I write about; and, I survived without a scratch, as the crash never actually happened. Two weeks earlier, I was at that same intersection, at that same time of night on a routine drive home. Two weeks earlier, the light changed to green, and I proceeded into the intersection to turn left, and I did, in fact, turn left. No incident occurred. Nothing to speak of even. Fast forward two weeks later when I was at that intersection again and the light turned green. I started to proceed, but then stopped abruptly – almost as soon as I had started, as I saw the speeding car coming from my left, not stopping. After the speeding car blew through the intersection, I proceeded to make my left turn and continued home, uneventfully. But don’t think for a moment that I didn’t realize how lucky I was. I thanked my “lucky stars” for keeping me safe that night.
Had I continued to make my turn as I did two weeks earlier, and countless times before, I would’ve gotten plowed on my driver’s side by the speeding car. My dash cam videos from the two nights prove it.

First, I synchronized the two dash cam videos using the changing of the traffic signals:

I advanced the videos to the point at which the speeding car was entering the intersection in the larger video. The smaller video shows where I would have been, had I proceeded as I did two weeks earlier. This combination of vehicle positions would have been the Point of Impact (POI) between the speeding car and my vehicle.

Let’s take a closer look at just the larger video image below:

As well as the corresponding frame from the smaller video, enlarged and shown below:

For reference, the silver fire hydrant visible just left of center in the first image is visible at the right edge of my headlight projection while turning in the second image. At the left edge of the second image, my dash cam is looking straight down the oncoming northbound lane of travel (i.e. this is the lane the speeding car was traveling in). Below is a lightened version of the second image:

So, my vehicle would have been impacted on the driver’s front corner, fender, and axle. The Principal Direction of Force acting on my vehicle would have been oriented back and to the right, passing ahead of (but close to) the center of mass of my vehicle. In the driver’s seat, I would’ve moved opposite the direction of the force, so I would have moved forward and to the left (i.e. toward the driver’s side). The impact would have rotated my vehicle clockwise, opening my driver’s door up to a secondary contact from the passenger side of the impacting vehicle. Had the impacting vehicle operator steered left in attempt to avoid, a head-on collision would have been the result instead. Had he steered right, his vehicle would have impacted directly on my driver’s door.

A basic approximation of the impacting vehicle’s speed from video was performed. The vehicle passed through the intersection while traveling its wheelbase in 4 frames of a 30 frame per second video.

Using the 111-inch wheelbase of a 2020 Honda Accord sedan for reference, the speed of the impacting vehicle would have been on the order of 47-mph in a 35-mph speed zone, hence my reference to “the speeding car” throughout. Additionally, it is noteworthy that impact would have taken place 9.33 seconds after the impacting vehicle operator’s traffic light had changed from green to yellow, or 5.33 seconds after his light had changed to red. He was faced with a red light for over 5 seconds at the time of this collision.

If my 25 years of accident reconstruction experience have taught me anything, it’s be alert, be cautious, be careful at all times of the day or night, no matter the road, no matter how far or close to home you may be. Thank you, thank you, thank you again to my “lucky stars.”

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Tags: Collision Reconstruction | James R. Schmidt


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