Which is correct about where this sign is installed?
To give advance warning, most caution signs are placed on the right side of the road a set distance BEFORE the hazard (Enforcement Rule, Appendix 6). First recall what kind of traffic flow two arrows pointing up and down in opposite directions announce, and do not mix it up with the placement rules of other caution signs.
Answer: ④
Explanation
The two arrows pointing in opposite directions form a caution sign warning that two-way traffic is in effect (Enforcement Rule, Appendix 6, No. 115). It is installed where a one-way road joins a two-way road, on the right side of the road 50-200 meters before two-way traffic begins. When you see it, expect oncoming vehicles and keep to the right. The other options describe the installation criteria of the right-lane-ends, median-begins, and keep-right signs.
Legal basis: 도로교통법 시행규칙 별표6 115 2방향통행표지