Crash-Prone Section Identification for Mountainous Highways Considering Multi-Risk Factors Coupling Effect

Table 1

Detailed information of the 8 risk factors.

Risk factor	Detailed information
Sharp turns	The radius of the circular curve of the highway is less than the minimum limit value of the circular curve corresponding to its designed speed, which can be seen in [11].
Continuous long downhills	The actual average longitudinal slope and slope length meet the definition standard, which can be seen in [12, 13].
Multiple tunnels	The actual length of the tunnel is more than 1000 m, which can be seen in [14].
	The distance between the actual continuous tunnel openings and the highway design speed meets the criteria, which can be seen in [15, 16].
Dangerous roadside environment	The roadside safety distance is lower than the standard requirement, which can be seen in [2].
	There are dangerous objects within the safe distance of the roadside [2].
	There are unreasonable installations of roadside safety facilities [2].
Rain	It is big rain with water film thickness greater than 0.120 mm [17].
Fog	The fog causes that the visibility is less than 200 m [18].
	The fog causes that the road adhesion coefficient is less than 0.4 [19].
Gale	Wind force is 5 and above [20].
Snow	The snow causes that the friction coefficient is less than or equal to 1/7 of dry road surface [21].
	The snow causes that the braking distance of the vehicle is more than 4 times of dry road surface [21].