Case Studies
Our team was asked to reconstruct a bicycle vs. passenger vehicle collision. An SUV was turning right out of a neighborhood onto a two-lane road one morning before sunrise while a cyclist was approaching the intersection from the right. The cyclist had a small headlight, and there was some ambient light from nearby streetlights. We were retained several years after the collision, but there were a few photographs taken after the crash in addition to a police officer’s bodycam video. Our investigation included an inspection of the collision site, the bicycle, and the SUV (which was not damaged in the collision). We also visited the site at night to observe and photograph the lighting conditions.
Our assignment was to assess the speed of the bicycle, reconstruct the collision sequence, and evaluate visibility for the motorist. To determine the speed of the bicycle, we looked at the bicycle gearing and terrain. Combined with published research, we used observations of which gear was engaged to get a range of speeds for the bicyclist. In addition, the cyclist was on a slight downhill stretch after a long uphill stretch. For the speed of the motorist, we relied on his statements combined with generally accepted acceleration rates for right turning vehicles. When we inspected the site and vehicles, we captured 3D laser scans to preserve the geometry. Using photogrammetry to extract 3D information from the provided photographs and bodycam video, we were able to recreate scrape marks on the roadway and the final resting position of the SUV, bicycle, and rider. We then simulated the motion of the vehicle and cyclist throughout the collision and were able to match the physical evidence. From there, we placed a virtual camera in the vehicle to represent the visibility from each person’s position. The vehicle was highly visible from the cyclist position. In one scenario, the bicycle was obscured by the B-pillar of the vehicle throughout his approach. This helped illustrate what may have caused the driver to not see the approaching bicycle on the morning of the collision.
Tyler Black
Area Lead
Accident Reconstruction Practice
+1 980 356 8526
[email protected]
> Accident Reconstruction
J.S. Held’s accident reconstruction experts deliver specialized expertise in forensic investigations, evidence collection and preservation, and scientific diagrams and animations. Our team of consultants, engineers, and PhD scientists is retained by first-party and third-party clients to provide expert witness and litigation support, from discovery to decision.
> Visualization & Reconstruction Services
J.S. Held’s forensic visualization experts specialize in the production of animations, graphics, interactive media, and virtual reality environments that communicate complex concepts in a simple form. Our visualization experts employ photogrammetry, nighttime visibility studies, video reenactments, photo analysis, video analysis, computer modeling, and simulation to analyze core issues of a case. These findings and results are represented though graphics, animations, physical models, interactive exhibits, and 3D visualizations to clearly and concisely explain our conclusions.