| | Vehicle factor group 1 | | Layer | Topics | Rate |
| | Layer 1 | Alignment | Left-curve, left-curve 1000 m more, straight | 5% | | Inclination | Downhill, downhill less than 1%, downhill 1% to 3%, downhill 3% more, downhill less than 500 m, flat | 3% | | Cut and fill | Flatness, fill height less than 2 m, fill height 2 m–5 m, fill height 5 m–15 m | 6% |
| | Layer 2 | Point of occurrence | Main lane | 1/2, 1/3, 1/4, 2/2, 2/3, 2/4, 3/3, 3/4, 3/5, 4/4, 4/5, 5/5 | 15% | | Shoulder | Shoulder, 2/2 | 1% |
| | Layer 3 | Traffic obstacle factors | Non-working section, stopped vehicle, normal | 15% | | Road environment | Dry | 8% | | Main accident cause | Tire damage, problem of device | 10% |
| | Layer 4 | Accident type | Side collision, single accident, shoulder others, shoulder guardrail, rear-end, head-on, angle | 7% | | Vehicle operation Just before the accident | Driving, others | 10% | | Main accident type | Vehicle-vehicle, others | 5% |
| | Layer 5 | Day and night | Daytime, nighttime | 8% | | Weather | Sunny, cloud | 7% |
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