TOKYO -- Japan aims for self-driving vehicles to account for more than 30% of new-car sales by 2030 as the country works to maintain its technological edge and narrow Europe's lead in forging rules for the field.

Those cars will run autonomously except in emergencies, achieving the so-called third level of automation out of five under international standards. The sales target will be part of a national growth strategy due in June from Prime Minister Shinzo Abe's government.

The strategy also entails rolling out self-driving transportation services in limited regions by 2020, with expansion to 100 locations nationally by 2030, as Japan aims to promote the technology and keep public transport running in depopulated areas. The installation of sensors to gather driving data, a must for this technology, will be discussed during fiscal 2018.

The 1968 Vienna Convention on Road Traffic, ratified by Germany and other European peers, has been updated to allow for autonomous-driving technology in situations where human operators can take over immediately. Those countries have an advantage over Japan, whose law is based on the 1949 Geneva road traffic convention -- an accord that has yet to address the issue.

Japan aims to revise its rules by fiscal 2020, including by assigning responsibility for accidents caused by self-driving cars. In March, the government set a policy to hold vehicle owners responsible for damages in such accidents, and discussions on criminal liability will proceed this fiscal year. Japan's insurers are getting ready to provide coverage for such accidents as well.

Artificial intelligence, a crucial technology in autonomous driving, also plays into broader measures to raise productivity. About 300 Japanese localities plan to use AI by the end of fiscal 2020 for handling such administrative processes as changes of address, death certificates and inheritance.

The Abe government's strategy also will seek greater use of data in health and medical care to extend healthy lifespans more rapidly than overall average life expectancy.

Other goals in the growth plan, the sixth under the current Abe administration, include boosting productivity at small and midsize businesses. The plan also will call for producing 20 companies with market caps of at least $1 billion -- known as "unicorns" -- over the next five years, as well as using robots and sensors in all checkups on aging infrastructure by 2030.