| | Other factor group 1 | | Layer | Topics | Rate |
| | Layer 1 | Alignment | Right-curve, right-curve 500 m–1000 m, right-curve 1000 m more, left-curve, left-curve 1000 m more, straight | 7% | | Inclination | Uphill, uphill less than 1%, uphill 1% to 3%, uphill 3% more, uphill less than 500 m, downhill, downhill less than 1%, downhill 1% to 3%, downhill 3% more, downhill less than 500 m, flat | 7% | | Cut and fill | Flatness, fill height less than 2 m, fill height 2 m–5 m, fill height 5 m–15 m, cut part less than 10 m, cut part 10 m more | 7% |
| | Layer 2 | Point of occurrence | Main lane | 1/2, 1/3, 1/4, 2/2, 3/3, 2/4, 3/3, 4/4 | 16% | | Shoulder, accelerate lane | 1% |
| | Layer 3 | Traffic obstacle factors | Non-working section, normal | 15% | | Road environment | Dry, wet | 8% | | Main accident cause | Poor loading, object on roads | 4% |
| | Layer 4 | Accident type | Single accident, shoulder guardrail, rear-end, head-on | 5% | | Vehicle operation just before the accident | Driving, others, overactive handle | 7% | | Main accident type | Vehicle-vehicle, vehicle-structure, others | 7% |
| | Layer 5 | Day and night | Daytime, nighttime | 9% | | Weather | Sunny, cloud | 7% |
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