You are driving a passenger car on an automobile road, and thick fog has cut visibility to only 80 meters. There is no variable speed limit sign. What maximum speed must you keep?
💡 Hint
In bad weather you must reduce the maximum speed by 20/100 or 50/100 depending on the conditions (Article 19(2) of the Enforcement Rule of the Road Traffic Act). For fog, visibility of 100 meters is the threshold, and do not confuse the maximum and minimum speeds of an automobile road.
Answer: ④
Explanation
The maximum speed on an automobile road is 90 km/h (Enforcement Rule Article 19(1)2). When fog or similar conditions limit visibility to 100 m or less, the maximum speed is reduced by 50/100 (Article 19(2)2), so 90 × 0.5 = 45 km/h. 72 km/h reflects only a 20/100 reduction, and 30 km/h is this road's minimum speed.
Legal basis: 도로교통법 시행규칙 제19조 제1항 제2호·제2항 제2호 가목