Tokyo officials and railway staff conducted water-defence training on the Arakawa bridge to practice flood-prevention measures on the Keisei Main Line [1].
The exercise focuses on a specific section of the Arakawa embankment that is lower than surrounding areas, making it a critical vulnerability during extreme weather. This location is particularly high-risk because the embankment was close to overtopping during a 2019 typhoon, with water levels reaching approximately one meter below the bridge deck [1].
The training began at 1 a.m. [1] on the tracks of the Arakawa bridge, which spans the river between Tokyo’s Katsushika Ward and Adachi Ward [1]. Because the work took place after the last trains had run, staff were able to install temporary stop-boards directly on the railway tracks to simulate the prevention of a river breach [1, 2].
Katsushika Ward Mayor Aoki Katsunori oversaw the operations. He said that residents of Katsushika Ward have a strong sense of crisis regarding water disasters because the town is surrounded by rivers [3].
"For the sake of safety and peace of mind, I want to continue these trainings firmly," Aoki said [3].
While the temporary boards provide immediate emergency protection, the city is working on a permanent solution. Raising the embankment to a safer height is a long-term project with a projected completion year of fiscal year 2037 [1].
In addition to the railway-specific training, the Tokyo Fire Department reported that about 600 people participated in a related large-scale water-defence drill simulating an Arakawa River flood [4].
“The embankment was close to overtopping during a 2019 typhoon, with water levels reaching approximately one meter below the bridge deck.”
The reliance on temporary stop-boards and training exercises highlights a significant gap in Tokyo's infrastructure that will not be fully closed until 2037. By practicing these deployments on the Keisei Main Line, officials are attempting to mitigate the risk of catastrophic transit failure and urban flooding in low-lying wards before permanent engineering projects are completed.
