What is the purpose of a rumble strip on the edge of a roadway?

Rumble strips are designed specifically to alert drivers they may be drifting out of their lane. These grooves or patterns on the roadway create a noticeable vibration and noise when a vehicle drives over them, which serves as an effective warning system. The primary goal is to help prevent accidents by drawing the driver's attention back to the road, particularly in situations where they might be distracted or drowsy. Their strategic placement along the edges of the roadway is intended to improve overall safety by catching the attention of drivers before they veer off course.

The other options suggest functions that rumble strips do not serve. For example, while stop zones and speed limit indicators contribute to road safety, they involve signage rather than tactile feedback. Similarly, while traction in rain is an important concern for roadway design, that function is typically addressed through road surface materials and not rumble strips.