B12 Prior Evaluation of Preventive Measures using Realtime Simulator
DOI: 10.1299/jsmemovic.2005.9.229
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Summary
This study addresses the high frequency of traffic accidents on the Meihan Highway (National Route 25) in Japan, specifically within the "Omega Curve" section. This area is characterized by complex road geometry, including sharp curves and steep slopes, and accounts for 50–60% of all accidents on the highway. Chronic overspeeding, driven by the highway’s position between two expressways, combined with inadequate road design for actual driving speeds, are identified as primary accident factors. The research focuses on the Nakahata section, a problematic segment featuring consecutive curves with short transition lengths, which induces unstable vehicle dynamics and steering errors. To evaluate preventive measures, the authors utilized a real-time driving simulator equipped with CarSim vehicle dynamics software and RT-Linux for real-time execution. The experimental design involved reproducing the current road shape of the Nakahata section and comparing it against a proposed improved design. The improvement involved replacing the existing "broken-back" curves with a single, smoother curve featuring a larger radius (350 m) and extended transition curves (85 m). Eight participants conducted driving trials at speeds corresponding to the regulatory limit (60 km/h), the average actual speed (90 km/h), and a high speed (120 km/h). Data collected included steering wheel angles and lateral acceleration rates to assess vehicle stability and driver control. The results demonstrated significant differences in driving stability between the current and improved road shapes. At the regulatory speed of 60 km/h, drivers maintained stable trajectories on the current road. However, at the actual average speed of 90 km/h, lateral acceleration rates exceeded safe limits (0.05 G/s) for most participants, indicating unstable and potentially dangerous driving conditions. At 120 km/h, nearly all participants experienced lane departure or loss of control. In contrast, the improved road shape allowed for stable driving at higher speeds. Steering data showed that the current design required frequent, abrupt steering corrections, whereas the improved design enabled consistent steering angles throughout the curve, reducing driver workload and vehicle instability. The study concludes that the current road geometry of the Nakahata section is inadequate for the actual speeds at which vehicles travel, creating a latent risk for accidents. The proposed geometric improvements, specifically extending transition curves and smoothing curvature changes, effectively mitigate these risks by allowing stable vehicle dynamics at higher speeds. This research validates the use of real-time driving simulators for the prior evaluation of preventive measures, offering a cost-effective method to verify the safety efficacy of road shape improvements before physical implementation.
Key finding
Simulator experiments demonstrated that an improved road geometry with extended transition curves and larger radii significantly reduces lateral acceleration and stabilizes steering inputs compared to the current sharp, discontinuous road shape.
Methodology
simulator
Sample size: 8
Provenance
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| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | author_sweep | — | — | 2 | 2026-05-28 |
| archive | success | canonical_url | — | — | 1 | 2026-06-04 |
| extract | success | cached | — | — | 3 | 2026-06-10 |
| clean | success | clean | — | — | 1 | 2026-06-04 |
| chunk | success | chunk | — | — | 1 | 2026-06-04 |
| embed | success | embed | Qwen/Qwen3-Embedding-8B | — | 1 | 2026-06-04 |
| enrich | success | — | — | — | 1 | 2026-05-28 |
| promote | success | — | — | — | 1 | 2026-06-04 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 2 | 2026-06-10 |
| tag | success | vector_similarity | — | — | 15 | 2026-06-11 |
| verify | success | — | — | — | 2 | 2026-06-10 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
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- Methodological Resource: validation psychometrics