完全に自動化された無人バスの実現へ向けての第一歩　　　　　　　　　　　　気ままなリライト６９

無人運転バス、定着挑む　「レベル4」公道走行解禁 - 日本経済新聞

As a hoped-for solution to the transportation challenges faced by people in areas with limited public transportation options, level 4 autonomy is gaining attention as a significant milestone in the development of self-driving technology, with the ultimate goal of achieving level 5 autonomy enabling vehicles to operate in all driving conditions without any human intervention. Level 4 autonomous vehicles are still being tested, with many regulatory and technical hurdles to be cleared. In addition, improvements in safety on the roadways and cost-efficiency are required before these vehicles are deployed in real-world driving situations in Japan.

While a level 4 autonomous vehicle is capable of operating without a human driver under limited situations, it still requires human intervention in certain situations. The vehicle navigates a designated route in a specific geographic area, using onboard sensors and systems to handle all aspects of driving, including acceleration, braking, steering, and environmental monitoring. While remote monitoring is used to optimize routes and provide updates on traffic conditions, the vehicle is not fully autonomous in all situations. In cases of severe weather, road construction, or emergencies where the vehicle is unable to navigate safely without human assistance, a human operator may be required.

When it comes to introducing level 4 autonomous vehicles as alternative public transportation, the narrow roads characteristic of the Japanese landscape are creating a barrier to safe operation of these vehicles without traffic accidents. According to the Ministry of Land, Infrastructure, Transport and Tourism, nearly 80% of roads across the country have an average width of only 3.8 meters. That leaves only 30% of roads with enough space for two large-sized vehicles to go through in opposite directions without a scrape. To minimize the risk of colliding with vehicles approaching from the opposite direction, integrating numerous high-powered sensors into level 4 autonomous vehicles is inevitable. The safer the vehicle needs to be for passengers, the more costly it tends to be.

When the government is aiming to expand level 4 autonomous mobility services to 50 locations by fiscal 2025,　funding problems could stand in the way of introducing level 4 autonomous vehicles on a larger scale in municipalities. While the government is providing subsidies to encourage municipalities to promote level 4 autonomy projects, it is not willing to cover the full cost of such projects with public funds. That could make it difficult for cash-strapped municipalities to secure alternative sources of funding for the implementation of an advanced sensor-equipped level 4 autonomous vehicle costing tens of millions of yen. A government-designated model project being carried out in Eiheiji Town, Fukui Prefecture, is an exception to this principle. During the period between April 2022 and December 2022, the local municipality tested a seven-seater autonomous vehicle on a public road with a two-kilometer straight line and carried a total of 600 passengers without any accident. The entire cost associated with the introduction and maintenance of the vehicle is being covered with public funds. Considering the potential for successful implementation of level 4 autonomous vehicles in the right circumstances, the municipality is planning to apply for operational approval for the vehicle within fiscal 2023.