High Quality Content by WIKIPEDIA articles! Rumble strips, also known as sleeper lines or audible lines, are a road safety feature that alert inattentive drivers to potential danger by causing a tactile vibration and audible rumbling, transmitted through the wheels into the car body. A rumble strip is usually either applied in the direction of travel along an edge- or centreline, to alert drivers when they drift from their lane, or in a series across the direction of travel, to warn drivers of a stop ahead or nearby danger spot. In favourable circumstances, rumble strips are effective (and cost-effective) at reducing accidents due to inattention. The effectiveness of shoulder rumble strips is largely dependent on a wide stable shoulder for a recovery.