Illinois CDL Practice Exam 2026 - Free CDL Practice Questions and Study Guide

Using hazard lights serves a crucial purpose in alerting other road users to potential dangers or unusual situations involving your vehicle. In this context, activating your hazard lights is most appropriate when your vehicle is stationary and poses a hazard to others. This situation can occur if you are experiencing a mechanical failure, have had an accident, or are otherwise unable to move your vehicle safely.

Hazard lights notify approaching drivers that there is a problem that could impede normal traffic flow or introduce a risk. By engaging these lights, you help reduce the chances of accidents by making your vehicle more visible and indicating to others to exercise caution as they approach.

In contrast, using hazard lights during heavy rain might not be necessary if you're driving safely and maintaining control. On the highway, it's generally expected that drivers maintain their lane and speed, so hazards are less relevant unless you're in a situation where you have to stop or slow down unexpectedly. Similarly, while entering a construction zone can warrant caution, there are specific guidelines for signaling in such scenarios that do not typically involve using hazard lights unless explicitly directed by signs or flaggers.