A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, ceramic, thermoplastic paint, glass or occasionally metal, and come in a variety of shapes and colors. Raised reflective markers, such as plastic, ceramic, or metal ones, include a lens or sheeting that enhances their visibility by retroreflecting automotive headlights, while glass road studs gather automotive headlights with a dome shape and reflect the lights with a reflective layer within. Some other names for specific types of raised pavement markers include convex vibration lines, Botts' dots, delineators, cat's eyes, road studs, or road turtles. Sometimes they are simply referred to as "reflectors". Convex vibration marking line The surface of this type of vibrating coating line is distributed and scattered with raised bumps. Some bumps are coated with high-refractive-index glass beads. When a speeding vehicle runs over the raised road lines, it produces a strong warning vibration to remind the car driver of deviation from the lane. Perpendicular to driving directions, these marking lines are used for settled mainline toll plaza, ramp entrances, mountainous areas, continuous sharp turns, downhill sections and the end of the highway (intersection of highway exit and the plane of the common roadway), gates and entrances of enterprises, institutions, and school. In the same direction of traffic driving direction, they are mainly settled in the median strip, edge lines, and dangerous sections of the road. Reflective raised pavement markers In the United States, Canada, Mexico, some countries of South America, Thailand and Australia, these plastic devices commonly have two angled edges facing drivers and containing one or more corner reflector strips. The marker is generally held in place using butyl pads, epoxy glue, or bitumen. In areas with little snowfall, reflective raised pavement markers are applied directly on top of the road surface. The device's retroreflective surface enables the device to be clearly visible at long distances at night and in rainy weather. The devices come in multiple colors which vary in usage depending on local traffic marking standards. In 1965 San Diego Police Motorcycle Officer Kenneth Grant Maine, improved upon, applied for a patent pending, and then submitted the white epoxy-resin reflective raised pavement markers to the California Bureau of Highways, the predecessor to the California Department of Transportation, now known as Caltrans. In areas where snowplowing is frequent, conventional markers are placed in a shallow groove cut in