Colors are out and letters are in.

The Metro Board of Directors on Friday approved a plan to overhaul the names of its rail and Bus Rapid Transit lines, starting with the Blue Line.

The expansion of the rail system is estimated to cost $8.9 million for the phased implementation and is deemed necessary since Metro is basically running out of colors to name its rail lines.

With eight lines already using up the basic colors, officials were worried they would have to start naming new lines using shades, which could get confusing—imagine having a “Lavender Line” and a “Purple Line.” The system is expected to double, eventually expanding to 16 total lines with funding from Measure M, passed in 2016.

To prepare for this, Metro wants to pair the colors with a letter to clarify its system and create consistency. The color-letter system is used in other, more transit-famous parts of the world, including New York City and Paris.

Since the Blue Line is in the midst of the New Blue Improvements Project, it’s the first to get the new naming treatment once it debuts to the public at the end of 2019, according to a staff report.

The under-construction Crenshaw/LAX Line will be next, changing to the “C Line,” according to a Metro blog post, since the new naming convention can be incorporated at no extra cost.

The rest of the lines will follow suit—with the exception of the Gold Line, which will actually turn into the Blue/A Line when the Regional Connector Project is finished. This project will connect Long Beach to Azusa for a “one-seat” ride.

The eastern segment of the Gold Line will join forces with the Expo Line (to be called the “E Line”) and will be shown in gold on the map to illustrate another “one-seat” ride between East L.A. and Santa Monica, the staff report said.

According to the report, staff held multiple focus groups before they landed on colors and letters as their recommendation.

“This prevents confusion with the numbering of the bus system and rail station platforms and provides an ample number of letter names to accommodate Metro’s planned transit lines,” the report said.

Colors and numbers had a brief glimmer of possibility, but was ultimately decided against because it would clash with the system’s numbers-only bus network.

As with any big change, the naming convention plan will be accompanied by a “robust public education and marketing program” to prepare riders for any confusion that may lie ahead.