In this section, ITARDA's in-depth study database is used to analyze the characteristics of single-vehicle accidents, focusing on pre-crash driver behavior.
1) Data used
ITARDA's in-depth study database is a collection of traffic accidents occurring in the Tsukuba area and its vicinity since 1993, now amounting to about 4,000 cases, examined by ITARDA with emphasis on those involving serious injuries and deaths. Among these, 123 single-vehicle accident cases reported in a recent 3-year period (2003 to 2005) are extracted that meet the following conditions:
- Road type: Highways and public roads
- Road shape: Non-intersection (straight and curved)
- Vehicle type: Standard- and mini-sized/light vehicles (for passengers and cargo)
2) Pre-crash driver behavior
A large proportion of drivers (72%) operated the steering wheel before the crash (Fig. 25), the major behavior among them being "Unconsciously operated" (39%), "Sharply swerved" (12%) and "Failed to negotiate a curve" (8%).
Other inappropriate behavior includes "No operation on a curve" (14%). ("Unconsciously operated" means that the driver was unaware of turning the steering wheel in such a way that the car ran off the road, due to taking his/her eyes off the road, dozing off, being distracted, etc.)
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