Study on Evaluation Models of Highway Safety Based on Catastrophe Theory

Table 2

The multilayer index system of first-class highways.

The general safety index	Second-layer index	Bottom-layer index
The safety level of a road section	Intersections	Traffic flows
		Traffic controls
		Channelization
	Road environment	Road surface condition
		Minor access point density
		Roadside design/obstacle
	Geometric designs	Quality of curve
		Sight distance
		Lane width and shoulder width
	Road facilities	Medians
		Barriers
		Street lightings
		Delineation