Longitudinal rumble strips consist of a series of milled roadway, raised traffic buttons or profile markings intended to alert inattentive drivers that their vehicle has left the travel lane by making vibrations and sound. Rumble strips can be placed on roadways with a posted speed limit of 50 mph or more. On undivided highways, rumble stripes can be installed along the shoulder near the travel lane as well as in the centerline. On divided highways, rumble strips can be installed on the median side (left-hand side) shoulder as well as on the outside (right-hand side) shoulder. Transverse rumble strips are intended to alert drivers to special conditions including: rural, high speed signalized or stop-controlled intersections with sight restrictions; unexpected urban intersections; newly installed stop or signalized controlled intersections; toll plazas; unexpected horizontal curves; or railroad crossings.

Shoulder and center line rumble strips illustration

Illustration: Shoulder and Center Line Rumble Strips

Shoulder and center line rumble strips photo

Photograph: Shoulder and Center Line Rumble Strips

A: Shoulder line

B: Center line

C: Rumble strip