What is an RPM?
A raised pavement marker (RPM) is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colors. Raised pavement markers include a lens or sheeting that enhances their visibility by reflecting automotive headlights. RPMs can be used to show roadway alignment, or to replac
e or supplement other pavement markings. More frequently, however, retroreflective RPMs are used in conjunction with retroreflective striping for longitudinal delineation. Retroreflective RPMs provide increased visibility at night, especially during rain to provide wet weather visibility.
What is an SPRPM?
A snow plowable raised pavement marker (SPRPM) serves the same purpose as a RPM but is designed to withstand the impact of snow plowing operations. The devices are usually made with a cast iron housing which holds and protects a plastic reflective lens. They are placed into a saw cut reservoir and are secured to the pavement using epoxy adhesive.
Reference: National Transportation Product Evaluation Program www.ntpep.org/Pages/RPM.aspx