Effects of Safety Facilities on Driver Distance Perception in Expressway Tunnels

Table 1

Installation setups in 5 experimental conditions.

Condition	Information Board	Flashing Light	Human-voice Broadcast	Siren Broadcast
1	×	×	×	×
2	√	×	×	×
3	×	√	×	×
4	×	×	√	×
5	×	×	×	√

Note: “√” means “activated”; “×” means “deactivated”.