California Department of Transportation


Q What are those little bumps in between the lanes on the freeway?

Those are known as raised pavement markers, or "Botts’ Dots." In 1953, Dr. Elbert D. Botts, working in the Caltrans materials testing lab in Sacramento, came upon the idea of using a raised pavement marker to help make the painted lines separating lanes last longer. After a many refinements, the use of Botts' Dots were mandated for all California freeways, except in areas where they would be damaged in snow-removal operations. The ubiquitous little buttons have since been adopted around the world. In addition to making lanes easier to distinguish, the markers also had an additional -- and originally unintended -- safety benefit: to alert motorists when they drift out of their lane. There are an estimated 20 million Botts” Dots in place today on California freeways and highways -- a lasting legacy to Mr. Botts, who passed away in 1962.