Shoulder rumble strips (SRS) continue to draw significant research interest around the world, with a particular focus on SRS impact on vehicle operation and maneuvers, driver safety, and road worker safety. Nevertheless, safety research has established since the 1980s the compelling safety value of SRS, and many states have specifications and policies in place for SRS use.
Dimensions and spacing design vary from agency to agency, though synthesis studies show surprising similarity in strip designs between states and even across strip construction methods; whether milled or formed, dimensions and spacing of strips remain fairly similar from state to state. Placement in shoulders varies dramatically, however, from under edgeline paintings to almost three feet from the outer lane edge. While continuous SRS seems favored by practicing agencies, intermittent design has been gaining attention in the last five years both for ease of construction and for providing bicyclists maneuverability on highway shoulders.