Japan’s Street Trees to Get Closer Scrutiny After Accidents

The Yomiuri Shimbun

7:00 JST, March 31, 2026

The government will strengthen inspections of street trees after a series of accidents caused by falling, aged trees.

The Land, Infrastructure, Transport and Tourism Ministry will ask local governments to make visual inspections at least once a year on roads where fallen trees or branches have been reported over the past five years, as well as on emergency transport and school routes.

The ministry published its first guidelines on inspecting street trees on Monday and notified local governments.

Street trees experienced a boom across the country in the period of rapid economic growth in the 1960s and ’70s, in a move to improve the landscape through greening and curbing air pollution, according to the ministry. There are about 7.2 million street trees nationwide.

In recent years, the trees have aged, leading to a growing number with hollow trunks caused by fungi or insects. Others have rotten roots. About 26,000 street trees fell between 2018 and 2022, with more than 14,000 toppling over in 2018, when torrential rains hit western Japan, according to the ministry.

Falling street trees often harm people and property. From April 2021 to November 2024, there were 801 incidents involving fallen street trees, with 33 involving injuries, one serious and 32 minor, a ministry survey found. In addition, 70% of municipalities and 30% of prefectures were not conducting regular patrols with close visual inspections, according to a separate survey conducted in fiscal 2024.

The ministry’s new guidelines list three priority levels for inspections based on the risk of a tree collapsing and the impact should an accident occur. The highest-risk category of “A” covers species that have fallen or from which branches have fallen along the same route in the past five years, as well as all trees on emergency transport and school routes. Regular patrols of these trees will be conducted once a year.

During these regular patrols, inspectors will visually inspect trunks, roots and branches from close range to check for cracks, rot and hollow trunks. If signs of increased risk are found — such as a large growth of mushrooms, extreme tilting or roots protruding onto the road — detailed investigations, including percussion tests by arborists, will be conducted. If a tree is viewed as likely to cause an accident, unnecessary branches will be pruned or the tree will be removed and possibly replaced with a sapling.

The second riskiest category, “B,” covers cherry and zelkova trees that are generally 40 years old or older, as well as trees near busy train stations and shopping districts. Inspections are expected to be carried out about once every few years. All other trees are classified as “C,” and they will be checked for abnormalities through visual inspections from vehicles.

“Thorough inspections by local governments are essential for properly assessing risks and responding promptly,” said a senior ministry official. “We want them to begin with major routes in accordance with these guidelines.”