If there's one actually deployed on a public road in California, I for one haven't come across it in the past decade or so. I do recall, as a kid, that a portion of I-80 between Sacramento and Roseville, just east of the Madison Ave. interchange -- when it was still 2 lanes per side (pre '73) -- had a "test section" like this, with multiple paint colors and thicknesses painted across both eastbound and westbound lanes. While most of the "stripes" were variations on white and yellow, occasionally a green or red stripe would be part of the mix. IIRC, there was a small white sign in either direction immediately before the test section stating that it was a "Pavement Marking Test Area".