Highway 5 Traffic Collision
A fatal traffic collision occurred at 5:10 PM Local Time on October 13, 2009, along the southbound lanes of Interstate 5 within 1 mile north of State Route 119 in Kern County, California. A total of 11 vehicles collided, and 6 of the vehicles caught fire. The collision and resulting fires ended the lives of three people. The cause of the collision was low visibility from a fast-moving dense cloud of dust from fields west of Interstate 5 blowing eastbound across the traffic lanes. The collision area is shown in Figure 1.
We were hired by attorneys representing plaintiffs involved in the traffic collision and, jointly, by the attorneys representing the owner of one of the nearby fields. We were asked to 1) review available documents and reports; 2) collect weather, soil, and geographic data in the area; 3) identify the possible sources of dust that could have caused the accident; and 4) perform air dispersion modeling and visibility impairment calculations to assess the atmospheric causes of the accident.
We determined that the accident scene clearly experienced a unique, extreme reduction in visibility, as reported by witnesses. From examining the local wind data, soil conditions of the fields, and the dust concentrations simulated using the US EPA AERMOD Modeling System, it became clear that only one field next to the accident scene could have create extremely high dust concentrations due to a combination of disturbed soils and proximity to the accident. Other fields could not produce comparable dust concentrations because of 1) lower dust emissions (undisturbed soils), 2) distance from the location of the accident, and 3) lack of alignment with wind direction at the time of the accident.
Our best estimate of the winds at the time of the accident is presented in Figure 2. The soil types in the area of interest are presented in Figure 3.
Our AERMOD computer simulations are presented in Figure 4. It is shown that the field West of Interstate 5 can produce dust concentrations of about 5 mg/m3 – a value that can create serious visibility impairments. Other fields create concentration impacts one to two orders of magnitude lower.
We also created semi-empirical animations to show the sight from the driver’s viewpoint, moving along the highway. The videos are presented here for a clean atmosphere and here with the presence of the dust cloud we modeled.
Our clients were able to successfully settle the case at the beginning of trial based in part on the powerful evidence we presented during expert depositions.
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|Figure 1 ||Figure 2 ||Figure 3 || |
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|Figure 4 ||Video 1 (low resolution) ||Video 2 (low resolution)|