AHS research at the California PATH program and future AHS research needs

The conceptual basis for automated highway systems (AHS) was established 70 years ago, long before it was technologically feasible. The historical context of thinking about AHS since then is reviewed, followed by a focus on the development of PATHpsilas research program on AHS during the past 20 years. The primary contributions to knowledge from the PATH AHS research are summarized, followed by identification of the key remaining issues that need attention.