Here you can download an article that describes the development in broadcasting traffic information since the seventies.
RDS is a milestone in this development with special features for spoken messages and RDS-TMC for coded messages still very widely used for navigation systems on all five continents.
RDS2 has the potential to offer a much-increased capacity without changing anything in the already existing international standards.
The future trend is however to distribute coded messages over the mobile internet using TPEG. The advantage is that information needed for the messages can then also be collected over a feedback channel directly from the devices used in modern cars.