What is the reason for slippery conditions in tunnels during Subject 4?
2 Answers
The reason vehicles tend to skid inside tunnels is due to slippery road surfaces. Since tunnels are not exposed to sunlight, they remain relatively dark, and combined with water dripping from the mountain walls, the ground becomes slippery. The Subject 4 exam consists of 50 questions, presented in the form of case studies, images, animations, etc., with a total score of 100 points, and a passing score of 90. Subject 4, also known as the Subject 4 theory test or driver's theory test, is part of the motor vehicle driver's license assessment. After the implementation of the Ministry of Public Security's Order No. 123, the Subject 3 test was divided into two parts: the road test and an additional safety and civics knowledge test, commonly referred to as "Subject 4," which evaluates "driving ethics." Because this test is conducted after Subject 3, it is colloquially called the Subject 4 exam. Officially, however, there is no "Subject 4." Failing Subject 4 does not require retaking previously passed subjects (Subject 1, Subject 2, Subject 3). Candidates can schedule a retake on their own, and no additional fees are required for the retake. There are no restrictions on the number of retakes, but the validity period of the driving skills test permit is three years. If the applicant does not complete the exam within this period, the results of any passed subjects will be invalidated.
In the subject four exam, it's mentioned that tunnels are prone to slipping, mainly because tunnels have high humidity and poor ventilation, with water or dew often accumulating on the ground, making tires more likely to skid when driving over. Additionally, many vehicles tend to brake hard upon entering tunnels, and frequent braking leaves behind rubber marks and oil stains, which accumulate over time and reduce friction on the road surface. In winter, if the temperature difference is large, there's even more moisture, making the road even slipperier. If you take sharp turns or drive at high speeds in such conditions, accidents are bound to happen. Therefore, it's essential to slow down in advance, maintain a safe distance, turn on your lights, and drive cautiously—safety first. I think this is an experience that requires practicing several times during driving lessons to truly understand.
