Illinois Rules of the Road Practice Test

A solid white line on the road indicates that changing lanes is discouraged. This marking serves as a warning to drivers that lane changes could be hazardous in that area. It typically appears in situations where the road conditions or the proximity to intersections, pedestrian crossings, or other factors suggest that staying in the current lane is safer. Drivers should be cautious and refrain from changing lanes when they encounter a solid white line to ensure the safety of all road users.

The other options suggest safety or encouragement in changing lanes, which contradicts the purpose of the solid white line. The intent of this marking is to promote caution and discourage sudden moves that could lead to accidents.