What feature may be found along the outer boundary of the lane to alert drivers if they drift?

Rumble strips are designed to provide tactile feedback to drivers when their vehicle drifts out of its intended lane. These strips, which can be found along the outer edges of the road or in the center of the lane, create a loud noise and noticeable vibrations when a vehicle drives over them. This auditory and physical feedback serves as an effective alert to help prevent unintended lane departures, improving overall roadway safety.

The other options, while they may sound relevant, do not accurately describe a feature used for this specific purpose. For example, wake-up tracks may refer to various types of alert systems, but they aren't specifically recognized in traffic management as rumble strips are. Belch lines and vehiquakes are not established terms in the context of roadway safety features, making them less applicable to the question at hand. Rumble strips remain the primary and most widely accepted method to alert drivers about lane drifting.