Japan decided Tuesday to allow highly autonomous "level-4" self-driving vehicles for use in transit and delivery services from April 2023.

Private cars will not be subject to the changes next year, with the automated vehicles intended to lead to the technology's use in unmanned bus services in regions with falling populations and in self-driving delivery robots.

File photo taken on Sept. 27, 2021, shows a "Level 3" vehicle driving autonomously with the driver taking his hands off the wheel on an expressway in Tokyo. (Kyodo)

Self-driving automation is classified into five levels starting at level-1, which allows either steering, brake or acceleration support.

At level-4, set to be permitted on April 1, a vehicle can conduct driving tasks without human intervention within a limited area, while a level-5 vehicle can drive itself anywhere under all conditions.

Private vehicles, classified as level-3, are already available, with Honda Motor Co.'s revamped Legend sedan becoming the world's first to reach the market in March 2021. Under certain conditions, including in congested traffic and on expressways, the car can operate itself while the driver engages in other activities.

Companies running transit services with level-4 automation will need permission from prefectural public safety commissions.

They will also be required to install long-distance surveillance systems for regular vehicle checks, and cybersecurity measures to ensure an unauthorized third party cannot take control of them.

In a push for greater use of automated vehicles, the Japanese government has set a target for more than 40 areas nationwide to use level-4 automated transit systems by fiscal 2025.

Firms operating automated delivery robots carrying goods and people driving level-4 vehicles will have to notify prefectural public safety commissions. The units are classified as small vehicles capable of operating remotely.

Their maximum speed is capped at 6 kilometers per hour, and they will operate on sidewalks and be subject to the same rules as pedestrians. The units will need to display a recognizable identifying mark and include a built-in emergency stop button.