Bott’s Dots Have Made Driving Safer throughout the World

Dr. Botts and Botts’ Dots

Dr. Elbert Dysart Botts worked with the California Department of Transportation or Caltrans where he oversaw research concerned with road markings and paint stripes. Caltrans began research on raised pavement markers as far back as 1936, but the research assumed real significance only after the war years. 1953, spurred by the increasing number of accidents that accompanied the economic boom, marked a watershed in the use of raised pavement markers. Prior to this, markings on road pavement were done with painted lines which tended to be obscured by dirt and to become almost invisible in rain.

The first of Botts’ dots were made of glass and attached to the road with nails. Once the dots got loose under traffic, the nails became a danger as they punctured tires. Further development led to the dots being made of ceramic materials and polyester. The problem of fixing them to pavement led to further research, which then came up with strong epoxy adhesives which replaced the nails and eliminated possible traffic hazards from them. While this epoxy is also credited to Caltrans, it is not known whether Dr. Botts was closely associated with this discovery, though with his being the head of research, credit would accrue to him as well.


Image Source: Frank Chan : Flickr

The Development of Botts’ Dots

Dr. Elbert Botts was a chemical engineer who used to teach at San Jose State College before he was inducted by Caltrans to head their research division Translab. His initial research concentrated on developing paints that would outlast concrete and also remain visible in poor light conditions. He had a background of having worked for a paint company for three years before moving to teaching. He even included glass beads in the paint to improve visibility through headlight reflections, but was unable to meet the standards required. This is when he switched to reflective pavement markers that stuck up above the road surface.

Most of the field work using various types of raised pavement markers was conducted on a new freeway in West Sacramento. The main idea of using raised pavement markers came from the fact that paint lines disappeared under water when it was raining, and the raised markers did allow for better visibility. Unfortunately Dr Botts died in 1962, two years after retirement at the age of 69, and his work was actually filed away, with even Translab failing to acknowledge it in connection with Dr. Botts. It was only in 1964 that the new head of Caltrans revived the research and developed the present day trend of using square reflectors between groups of the polyester dots.

The Application of Bott’s Dots

The system got tacit recognition when the state legislature made the use of Botts’ Dots mandatory in 1966. Botts’ Dots are now being used in various colors and in conjunction with painted and other reflective markers which make roads safer. Yellow dots indicate a split in the road, whereas red markers indicate lines that cannot be crossed. They are also used across the road as rumble strips warning motorists to slow down. Blue dots are used to indicate areas around fire hydrants.

Botts’ Dots come in two different basic types. These are either reflective or plain. The plain ones are white or amber colored and are made of ceramic or plastic material in a dome shape. The reflective ones are made of polyester that can take high impact and are square in shape. White dots indicate parallel lanes while center markers are amber. Red dots are an indication that the driver is in the wrong lane and needs to get off immediately.

There is a difficulty in using these dots in areas with heavy snowfall as they can be dislodged by snow clearing equipment. These markers are then put on divots in the road. One aspect of the dots that has led to its acceptance was the discovery that they made a thumping noise when tires passed over them, and that, along with the bumping motion that they created, served notice to drivers that is especially helpful when driving conditions are poor on rainy days.


California Department of Transportation

Botts’ dots

Raised Pavement Markers