Variations in Naturalistic Driving Behavior and Visual Perception at the Entrances of Short, Medium, and Long Tunnels

Table 1

Test tunnel data.

Number	Name	Length (m)	Radius of horizontal alignment (m)	Gradient (%)
1	Ligongding Tunnel	325	3,200	2.20
2	Xi-an Tunnel	286	2,515	2.45
3	Shimen Tunnel	768	2,550	2.28
4	Fengkeng Tunnel	762	3,720	1.72
5	Nanmuling Tunnel	1,660	3,600	1.60
6	Dajuekeng Tunnel	1,442	2,900	0.50