Inspecting The Crash Site Is Critical | Accident Reconstruction Experts

When an accident reconstruction expert is investigating how an accident happened, a site inspection can provide vital information. This was shown to be true in a case where early one morning in the darkness before dawn, a large sedan was traveling southbound on an unlit 4-lane divided rural road with a small grass median between the opposing lanes. The sedan collided with the side of a low-boy construction trailer that had stopped while making a left turn across the sedan’s lane. A construction gate on a driveway had been closed and the northbound tractor/trailer had to stop, as he could not complete his turn into the construction site. A northbound witness said that she had a clear view of the trailer in spite of the darkness and couldn’t understand why the southbound sedan had hit it.

My investigation of the site and other factors led to a clear conclusion that the sedan driver would not have been aware of the trailer’s presence and that he could not have observed the trailer in time to avoid the collision. The trailer had minimal side lighting and several strips of dirty reflective material on the sides. Equipment on the trailer was being delivered to the construction site before dawn, even though the trailer was not permitted to be on the highway outside of daylight hours.

Evaluation of the site led to a prominent visibility factor. The northbound approach to the trailer was slightly uphill, leading to a crest in the area where the trailer was stopped. In the darkness, this contour of the ground caused the low-beam headlights of the northbound driver to shine higher, and they illuminated the trailer as she approached. Conversely, the southbound approach was slightly downhill to a short, more level area just before the trailer. This ground contour decreased the effective distance for his headlights, and they did not serve to illuminate the side of the trailer prior to his reaching the level area. By the time he did reach level ground, there was not enough time and/or distance remaining to avoid a collision.

Additionally, the lighting of some signs in the background of the downhill southbound approach served to mask the (dirty and barely visible) reflective strips on the side of the low-boy construction trailer. The reflective strips were not applied in a readily identifiable pattern, since the configuration of the trailer did not allow a straight, continuous line typical of a tractor/trailer combination with a cargo box. The reflective strips were not readily discernible from the random background lights.

The inspection of this crash site permitted a more complete evaluation of conditions at the time of the crash and produced an understanding of the difference in the visibility of the trailer from opposing directions.

When a reconstructionist is investigating how an accident happened, a site inspection can provide vital information. This was shown to be true in a case where early one morning in the darkness before dawn, a large sedan was traveling southbound on an unlit 4-lane divided rural road with a small grass median between the opposing lanes. The sedan collided with the side of a low-boy construction trailer that had stopped while making a left turn across the sedan’s lane. A construction gate on a driveway had been closed and the northbound tractor/trailer had to stop, as he could not complete his turn into the construction site. A northbound witness said that she had a clear view of the trailer in spite of the darkness and couldn’t understand why the southbound sedan had hit it.

DONALD EISENTRAUT, BSME, P.E., ACTAR, is a mechanical engineer at ARCCA, specializing in vehicular accident reconstruction and forensic analysis of crash protection systems and components.