Botts dots, otherwise known as raised pavement markers, are being phased out by Caltrans and many local agencies.  These dots, named for long-retired Caltrans engineer Elbert Botts who invented them about 50 years ago, have been the primary warning device since then for drivers who were drifting out of their lanes.  Now, two factors are behind the change to reflective and wider lane lines:  1. elder drivers have an easier time seeing the reflective paint, and 2. self-driving cars can't see the dots-only lane lines.  See https://www.sacbee.com/news/local/transportation/article127811959.html for more.