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Different Types of Reflective Pavement Markers

January 7, 2020

Pavement markers come in many forms and are usually easy to spot by drivers. The type that includes raised reflectors are helpful in snowy climates and can also serve as speed bumps. Here are explanations why reflective pavement markers (RPMs) are common across the United States and why there are a variety of different markers.

Cat’s Eyes and Bott’s Dots

The earliest use of RPMs on roads started in the Great Depression era with “Cat’s Eyes” made of glass and rubber. They were designed to help drivers see the road better and proved to be useful during World War II blackouts. Over time, these colored reflectors grew in meaning and evolved to include different materials such as aluminum and ceramics.

The invention led to a refined version in California called “Bott’s Dots” in the 1960s, except these raised dots were not reflective but were accompanied with reflective material. By that point, cars had become omnipresent on roads, and it became clear that painted lines were difficult for drivers to see in the rain.

Since then, Bott’s Dots expanded to other states including Arizona and Washington, although Arizona went with Stimsonite reflectors in the nineties. Stimsonite markers are raised with reflectors and are made of plastic, ceramic, glass or metal. California announced in 2017 that it would discontinue using Bott’s Dots as the key indicator dividing lanes due to issues of cost and worker safety. The state aims to make reflective pavement markers wider and thicker, so that they are more easily detected by self-driving vehicles.

Over 20 million Bott’s Dots have been installed in California, but will be replaced over time with cheaper markers that are safer to install. The new solution involves thermoplastic white striping melted onto pavement.

Modern RPMs are commonly made of aluminum in a round shape with a three inch diameter. They are designed to last many years while the FHA does not have a current standard for minimum reflectivity. It’s up to each local jurisdiction to determine how much reflectivity is needed for public safety.

Enhancing Visibility with Retroreflectivity

The concept of retroreflectivity involves using lens that make car headlights more visible, reflected by glass domes. These markers are color-coded to help drivers understand them better. Orange markers are placed outside of double-yellow lines and are used to separate two-way traffic. A blue marker means there is a nearby fire hydrant. Green markers indicate an entrance for emergency vehicles while red markers mean the area is closed for traffic.

A further visibility enhancement is the use of solar-powered LEDs on pavement markers, which improve intersection safety, according to the Federal Highway Administration. These devices have built-in sensors that switch on automatically when ambient light is reduced. Similar pavement markings can also be wired to a traffic signal controller and detect traffic.

LED RPMs provide greater visibility than conventional RPMs, particularly in adverse weather conditions and in rural areas. But hard-wired LED RPMs have proven to give off more light than solar versions. In construction zones and other places where safety is an issue, plastic and fiberglass raised pavement markers are effective. These RPMs work well on concrete pavements, are easy to install and provide enormous savings.

Ultimately, RPMs are useful in alerting drivers of lane divisions when visibility is low. Not only do they help drivers in rainy and slippery conditions, they help the elderly see roads better.


RPMs are helpful for increasing visibility in dark areas, especially at intersections used regularly by pedestrians. Contact Zumar at our Arizona, California or Washington location to learn more about reflective pavement markers and other traffic control devices.

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