Crash causes, countermeasures, and safety policy implications.

Area of Science:

• Traffic Safety Research
• Accident Analysis
• Public Policy

Background:

• Established notions of crash causation, particularly the "90 percent human error" paradigm, are based on flawed assumptions and investigator bias.
• The seminal 1979 Indiana University "Study of Accident Causes" has perpetuated these inaccuracies, hindering effective policy development.
• Current approaches to defining crash causes and developing countermeasures lack a balanced perspective.

Purpose of the Study:

• To critically examine the definition of crash causes and their relationship with countermeasures.
• To challenge the prevalent assumption that approximately 90% of crashes are due to human error.
• To advocate for a more balanced and effective approach to traffic safety policy.

Main Methods:

• Analysis of existing literature on crash causation and countermeasures.
• Critique of the "Study of Accident Causes" and its impact on current assumptions.
• Exploration of alternative frameworks for understanding crash causality.

Main Results:

• Investigator bias significantly influences the classification and prevalence of crash causes.
• The "90 percent human error" statistic is a result of threshold bias, not necessarily accurate causation.
• Directly linking 90% of countermeasures to "human error" is based on an erroneous assumption.

Conclusions:

• A re-evaluation of how crash causes are defined is essential for effective safety interventions.
• The "safe system approach" offers a promising framework for developing balanced and effective crash countermeasures.
• Overcoming ingrained assumptions is critical for advancing traffic safety policy.