The results of the National Transportation Safety Board investigation excluded many potential causes of the accident: weather; driver's experience and familiarity with his vehicle and area; alcohol; illicit medications; insuffi cient sleep or fatigue; pedal placement or vehicle failure. The report concluded that the driver unintentionally accelerated his vehicle. The driver made an error in response execution, inadvertently accelerating when he intended to brake, that resulted in the collision with the Mercedes. The driver failed to detect his error in response execution, thereby inadvertently accelerating his vehicle and propelling it through the Santa Monica farmers' market. The driver most likely reverted to the habitual response of hard braking or "pumping" the brakes as his stress level increased and the vehicle failed to slow, but because his foot was on the accelerator instead of the brake pedal, this response led to increased acceleration. The ineffectiveness of the driver's efforts to stop his vehicle and the realization that he was striking objects in his path very likely increased the already high level of stress affecting him, thereby impeding his ability to quickly detect and correct his earlier error in response execution.
CASE STUDY ANALYSIS
The accident at the Santa Monica Farmers' Market remains nothing less than a personal and national tragedy. On that perfectly ordinary summer day, an intelligent, grandfatherly 86-year-old man was involved in a horrifi c auto accident. Although no one can ever predict an accident, it turns out that a trained eye might have detected enough warning signs to raise concern about his driving fi tness. He exhibited several of the warning signs detailed earlier in this chapter. The investigative reports of the accident noted: vision impairment (corrected with glasses); mobility issues (history of bilateral hip replacement, spinal stenosis, arthritis of such severity that a disabled parking placard was issued; pain in the right thigh, and cane required for walking); and medication (prescription and overthe- counter) use. Perhaps most striking of all the warning signs was a recent history of minor auto accidents (3 in 10 years). Three weeks after the crash, a cardiologist diagnosed a serious heart problem in George and implanted a dual chamber pacemaker.
Admittedly, hindsight is always 20/20. But in retrospect, it seems that George clearly had enough warning signs to at least raise concerns about his driving fi tness. The truth is that predicting future accident risk is not yet an exact science. It is not clear who is responsible for assessment, either. If an older driver cannot or does not heed warning signs, who should? A state's department of motor vehicles? The police? Physicians? Family members? Neighbors? Research and vigorous debate about these fundamental policy questions is lacking and yet never more urgently needed. Because you are reading this book, I assume that you have more than a passing interest in the topic. I hope that you will push these questions toward the front burner for decision makers.
Determining Driving Fitness: Ability to See, Think, and Move
This section reviews the main skills and functions needed to safely operate a vehicle. As I've mentioned, in order to drive safely, a person must be able to see, think, and move well and with ease. If any of these abilities is limited, the driver could be at risk.