Japan transport ministry sets four-level flood risk plan for underpasses
Version 2: The update adds land and transport minister Ibayashi's public statement on the barrier plan and Asahi Shimbun's figures: 3,841 underpasses nationwide, two deaths in the August Chiba rain and one in Iwaki in September, preemptive restrictions already decided at 22 national highway sites, and staffing shortages as an existing problem.
In short
Japan's Ministry of Land, Infrastructure, Transport and Tourism published guidelines on October 6 classifying underpasses nationwide into four flood-risk levels and calling for remotely operated or automatic barriers at the most dangerous sites. Land minister Ibayashi said barriers would be installed at locations with especially high flood risk. The measures follow deaths when vehicles were submerged in August heavy rain in Chiba Prefecture and a fatal accident in Iwaki, Fukushima Prefecture, in September.
Read the full story 2 min read
Japan's Ministry of Land, Infrastructure, Transport and Tourism published guidelines on October 6 on preventing flooding accidents at underpasses, according to Yomiuri Shimbun, Yahoo! News Japan, Nishi-Nippon Shimbun and Asahi Shimbun. The policy requires underpasses nationwide to be sorted into four flood-risk levels and calls for barriers at the most dangerous sites. Jiji Press reported that land and transport minister Ibayashi said barriers would be installed at underpasses with especially high flood risk. [ 1 , 2 , 3 , 4 , 5 , 7 ]
At locations classified as the most dangerous, where deaths or damage have occurred in the past, the ministry asks road managers to install barriers that can be operated remotely, or automatic barriers that activate when they detect flooding, Yomiuri Shimbun reported. It also requests preemptive traffic restrictions when disaster weather information equivalent to warning level 4 is issued, or when hourly rainfall, including forecasts, reaches a set amount, and asks for road information boards and red lights at underpasses regardless of risk level so that closures can be communicated immediately. Existing subsidies can cover the costs, the newspaper said. [ 1 , 7 ]
Nishi-Nippon Shimbun reported that the policy follows deaths when vehicles were submerged during heavy rain in Chiba Prefecture in August, and that a fatal accident also occurred in September on a city road section in Iwaki, Fukushima Prefecture. Asahi Shimbun reported that two people died in the Chiba rain and one in Iwaki in September. [ 4 , 5 , 7 ]
Asahi Shimbun added that the ministry had already decided to introduce preemptive traffic restrictions at 22 national highway locations when heavy rain is forecast, and that a shortage of personnel to enforce the restrictions had been an issue. It put the number of underpasses nationwide at 3,841 and said the measures were included in guidelines aimed at the municipalities and other bodies that manage roads. Nishi-Nippon Shimbun said there are about 3,800 underpasses, managed by the national government or municipalities, and described them as road sections whose height drops sharply because they cross under roads or railways. [ 5 , 7 ]
Yahoo! News Japan reported that the guidelines, addressed to local governments and national regional bureaus, were intended to ensure that cars are not allowed to enter an underpass during flooding, citing ministry officials. The documents do not state how many underpasses fall into the highest-risk category, when installation work will begin, or whether the guidelines are binding on local road managers. [ 4 ]
Why it matters
The guidelines give municipalities and national regional bureaus a common framework for underpasses that flood, after fatal submersion cases highlighted the interval between flooding and road closure. Because the ministry is issuing guidance to road managers rather than announcing binding rules, how quickly barriers and preemptive closures spread depends on local authorities. The documents describe funding through existing subsidies, and Asahi Shimbun reports that staffing for restrictions was already a problem.
Key facts
- The Ministry of Land, Infrastructure, Transport and Tourism published guidelines on October 6 for municipalities and national regional bureaus on underpass flood safety. [ 4 , 5 , 7 ]
- Underpasses nationwide are to be classified into four flood-risk levels according to terrain and past accidents. [ 1 , 4 , 5 , 7 ]
- At the highest-risk locations, the ministry asks for remotely operated barriers or barriers that activate automatically when they detect flooding. [ 1 , 2 , 4 , 5 , 6 , 7 ]
- Preemptive traffic restrictions are requested when disaster weather information equivalent to warning level 4 is issued, or when hourly rainfall including forecasts reaches a set amount. [ 1 , 7 ]
- Road information boards and red lights are requested at underpasses regardless of risk level, with existing subsidies available for the costs. [ 1 ]
- Nishi-Nippon Shimbun put the number of underpasses nationwide at about 3,800, managed by the national government or municipalities, while Asahi Shimbun reported 3,841. [ 5 , 7 ]
- Asahi Shimbun reported that two people died in the August heavy rain in Chiba Prefecture and one in Iwaki, Fukushima Prefecture, in September, and that the ministry had already decided on preemptive restrictions at 22 national highway sites. [ 7 ]
Confirmed by several sources
- The transport ministry published a policy on October 6 to classify underpasses nationwide by flood risk and to require barriers at the most dangerous sites. [ 1 , 4 , 5 , 7 ]
- The most dangerous category covers locations where deaths or damage have occurred in the past. [ 1 , 5 , 7 ]
- The measures follow fatal submersion accidents at underpasses, including during heavy rain in Chiba Prefecture in August. [ 4 , 5 , 7 ]
- A fatal accident also occurred in September on a city road section in Iwaki, Fukushima Prefecture. [ 5 , 7 ]
- Central government minister Ibayashi, the land and transport minister, stated the policy of installing barriers at underpasses with especially high flood risk. [ 2 , 3 , 5 ]
Still unclear
- Whether the guidelines are binding on municipalities or are requests. One document describes the ministry asking road managers to take measures, and another describes requests for equipment; neither states whether compliance is mandatory.
- How many underpasses fall into the highest-risk category, and when classification will be completed. The documents say classification will be carried out but give no figures or completion date.
- How much the barriers and other equipment will cost and when installation will begin. Only the use of existing subsidies is stated; no budget figure or schedule appears.
- Details of the staffing shortage for preemptive restrictions. Asahi Shimbun alone reports that a shortage of personnel to enforce restrictions was an issue, without further detail.
- Details of the September fatal accident in Iwaki. Mentioned by Nishi-Nippon Shimbun and Asahi Shimbun with no further information on the circumstances.
What local media are saying
Timeline, local time
- Yomiuri Shimbun publishes the details of the guidelines, including remote and automatic barriers, preemptive restrictions and the use of existing subsidies. [ 1 ]
- Jiji Press reports that land minister Ibayashi said barriers would be installed at underpasses with especially high flood risk. [ 2 ]
- Jiji Press reports the plan to install barriers at high-risk underpasses ahead of heavy rain. [ 3 ]
- Yahoo! News Japan reports the ministry's decision on four risk levels, remote barriers and preemptive restrictions, with guidelines to be published the same day. [ 4 ]
- Nishi-Nippon Shimbun reports the four-tier classification and remote barriers, and cites the August Chiba deaths and the September Iwaki accident. [ 5 ]
- Tokyo Shimbun carries the four-tier classification and remote barrier report with a photo of a flooded underpass in Chiba City dated August 14. [ 6 ]
- Asahi Shimbun reports the guidelines, the national total of 3,841 underpasses, the death toll in Chiba and Iwaki, and existing preemptive restrictions at 22 national highway sites. [ 7 ]