On December 21, Nobuhiro Maeda, president and representative director of Metropolitan Expressway, held a press conference to explain the renewal plan.
On December 22, 2021, exactly one year ago, the company established the “Technical Review Committee for Large-Scale Renewal, Repair, and Enhancement of Metropolitan Expressways,” chaired by Professor Koichi Maekawa of Yokohama National University, to discuss structural damage, the need for renewal, and new findings. The committee has now compiled a summary of its findings.
Currently, of the approximately 327 km length of the Metropolitan Expressway, approximately 64 km are undergoing renewal projects, and since FY2014, the company has been conducting close visual statutory inspections once every five years, and after the first round of these inspections, it was found that there were areas over approximately 22 km where damage was more pronounced than expected, making drastic measures necessary. The company estimates the cost to be approximately 300 billion yen. In addition, there is a possibility that damage similar to the 22 km that required renewal may become apparent in the other approximately 241 km, and in that case, the company will consider additional projects.
New areas requiring renewal include the Haneda Tunnel and the Arakawa Bay Bridge, among others.
In the former case, approximately 60 years have passed since the opening of the road, and the structural joints (joints) have become weak points, causing seawater intrusion, partial loss of rebar due to corrosion on the road and duct floors, and concrete delamination on the upper surface of the middle slab, etc. Although repairs have been made repeatedly, the road is facing problems such as increased frequency of emergency traffic control. Although repairs have been made repeatedly, the project is facing problems such as an increase in the number of emergency traffic restrictions.
As for the latter Arakawa Bay Bridge, although it was sound at the time of the 2010 inspection, in 2020 it was found that the members had broken off due to corrosion. The chlorinated rubber-based paint used had lost most of its adhesive strength, exposing the steel plates, which led to the corrosion.
Similar steel corrosion due to coating deterioration has also been found to be occurring on other bridges (Ikebukuro Line, Mukojima Line, Komatsugawa Line, Yokohane Line, Kariba Line, etc.).
Furthermore, the slab thickness was thin in comparison to the 1972 and later standards, and although the slab was supported by reinforcement from below, the reinforcement was damaged and corroded due to deflection.
The Haneda Tunnel will be reinforced, the walls repaired, and the joints replaced, while the Arakawa Wangan Bridge and other bridges will have their existing paint removed and repainted (related article: “Tokyo Metropolitan Expressway Haneda Tunnel to be Revamped with Three Lanes of Elevated Tunnels and Tunnel Exclusively for Downbound Traffic. (Related article: “Tokyo Metropolitan Expressway Haneda Tunnel to be reexamined to make it three lanes up and a tunnel dedicated to down traffic.)
Regarding the allocation of the 300 billion yen budget and the specific timing of the start of the project, he explained that there is no immediate time frame because of the need to secure financial resources and approve the project plan, but that since damage has become apparent, he would like to proceed with the project as soon as possible, including close examination of each section.
© Source travel watch
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