What does 'white low, yellow high, black suggestion' mean?

[AngelaAnn]

On the road, yellow suggests slowing down, 'high' indicates a highway ahead, white represents a ramp, black means stop, and 'low' refers to low-frequency honking. Driving precautions are as follows: 1. Prevent fatigue driving: Fatigue reduces a driver's judgment, slows reaction times, increases operational errors, leads to untimely or inaccurate gear shifts, and may even cause brief sleep episodes, resulting in loss of vehicle control. 2. Never drive under the influence of alcohol: Alcohol increases blood alcohol concentration, leading to central nervous system paralysis, reduced rationality and self-control, impaired vision, narrowed field of view, lack of concentration, and weakened balance, causing delayed responses and sluggish actions when operating brakes, acceleration, or clutch pedals. 3. The dangers of speeding: Speeding causes mental stress, consumes significant psychological and physical energy, reduces vision, narrows the field of view, and impairs judgment, directly affecting the driver's operational stability.