Crash Trifecta: A Complex Driving Scenario Describing Crash Causation

When determining crash causation, crash databases emphasize a single, unitary critical reason (CR) as the primary proximal cause of a safety-critical event (SCE), which leaves no room for the specification of any other potential contributing factors to the crash/event genesis. This is despite the fact that it is well established in the transportation safety field that crash genesis typically involves a convergence of several factors. The aim of this study was to investigate the crash trifecta concept to determine if the convergence of multiple elements, rather than a single, unitary critical reason, has greater value in explaining the complexities of crash genesis. Specifically, the crash trifecta concept is defined as three separate, but converging, elements: 1. Unsafe pre-incident behavior or maneuver (e.g., speeding, tailgating, unsafe turn); 2. Transient driver inattention (which may be driving related, such as mirror use, or unrelated, such as reaching for an object); and 3. An unexpected traffic event (e.g., unexpected stopping by the vehicle ahead). The value of the crash trifecta concept and convergence concepts in crash causation is that these concepts provide a structure for understanding the complexities of crash genesis. Thus, the crash trifecta concept may help explain the differences between the genesis of a crash and lower-severity SCEs (e.g., near-crashes).