Geoscience Reference
In-Depth Information
EXAMPLE 9.1 *
The following facts are to be considered in this example:
1. The time was 8:40 a.m. on a Sunday.
2. A single car, occupied by the driver only, struck the concrete uprights of a bridge pier.
3. The driver was pronounced dead on arrival at the hospital 15 minutes after the crash. He
suffered a compound comminuted fracture of the skull after being thrown from the vehicle
and his head struck a concrete pillar.
4. The roadway was wet, and it was possibly raining hard during the accident; it was
daylight.
5. The roadway was a divided, limited-access highway with three lanes each way.
6. The accident took place 200 feet before an exit ramp to the right. The uprights that were
struck were off the road to the right.
7. Traffic controls consisted of speed-limit signs (45 mph), broken white-lane-divider lines, a
solid white line dividing the roadway from the 10-foot shoulder, and exit signs.
8. The vehicle was a 1964 Pontiac Catalina, recently inspected, that had traveled 72,843
miles. Mismatched tire sizes and tread types may have contributed to the accident.
9. At impact the left front door detached as a result of broken hinges. The driver was thrown
from the vehicle. Lap-belts were not being used at the time of the accident. The car spun
around 180 degrees clockwise.
10. The driver, 19 years of age, was alleged to suffer blackouts and nystagmus. He was familiar
with the area. Alcohol tests proved negative.
11. According to a witness, the vehicle was traveling at 90 to 100 mph when the vehicle veered
to the right beneath the overpass and struck one of the concrete uprights.
12. After impact the left rear tire was seen to be deflated.
The pertinent facts for Boolean analysis are as follows (with the applicable item number in
parentheses):
• The wet roadway contributed to the loss of control (4).
• It was raining hard, with limited visibility (4).
• Bridge uprights and exit ramp caused confusion (6).
• Improper trafic controls were in place (7).
• Mismatched tires caused loss of control (8).
• Door hinges were weak (9).
• Lap belts were not installed (9).
• Shoulder belts were not installed.
• Driver illness caused the accident (10).
• Speed contributed to the loss of control (11).
• The left rear tire blew out and caused the accident (12).
• There were no guardrails to prevent direct impact with the bridge piers.
Although the Boolean operators are stated as facts, there is no implication that they are all true. In
fact, the following “contradictions” are significant.
• Not (C): Driver was familiar with the area, thus no confusion.
• Not (D): Trafic controls were standard for this type of highway and speed limit (45 mph)
and were adequate.
* This example is from USDOT, Summary of Multidisciplinary Accident Investigation Reports , 2(4), 143, 1998.
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