General Knowledge · Driving in Fog
Why shouldn't a driver in fog assume that a set of taillights visible ahead marks the safe location of the road?
Explanation
A driver should not assume a set of taillights or headlights visible ahead in fog marks the true location of the road, because the vehicle those lights belong to may itself have drifted off the roadway, and following it could lead the following driver off the road as well; roadside reflectors, not another vehicle's lights, are the more reliable guide to how the road curves ahead. Fog is not named anywhere in the required knowledge topic for extreme driving conditions, 49 CFR 383.111(a)(12), whose examples are bad weather (snow, ice, sleet, high wind), hot weather, and mountain driving; the closer match is the broader safe-operations umbrella at 49 CFR 383.111(a)(1)(ii), "procedures for safe vehicle operations," which points generally at driving safely rather than naming any specific hazard, so this fact is standard driver-training guidance rather than a codified federal rule. The other options fail for a shared reason: each invents a rule or condition, a taillight-disconnection requirement, a visibility-only-when-stopped effect, or an automatic tailgating violation, that does not exist and does not explain the actual risk of trusting another vehicle's position in fog.
Source: 49 CFR 383.111(a)(1)(ii)
Related Driving in Fog questions
- Why does the guidance for driving in fog say to slow down before entering a fog bank, rather than waiting until visibility is already reduced?
- Why should a driver use low-beam headlights, not high beams, when driving through fog?
- If fog becomes so dense that a driver cannot see far enough ahead to drive safely, what should the driver do?
- Why should a driver avoid passing other vehicles while driving in fog?