This article reviews R&D activities on automated highway systems (AHSs) since 1950s with emphasis on recent ones. AHSs in the 1950s and 1960s were featured by a cooperative system between roads and vehicles; those in the 1970s and 1980s were by autonomous systems. Intelligent transport system (ITS) projects since 1980s regarded AHS as an important system, not only a single automated vehicle but also an automated platoon were developed. In recent years, the R&D focuses on automated transit buses aiming at precision docking and driving along a narrow lane and automated truck platoons aiming at energy saving. The automated driving can be common ground of automobiles and robots.