On May 16, the Metropolitan Expressway opened to the press the construction site of the Daishi Bridge (Ota-ku, Tokyo to Kawasaki City, Kanagawa Prefecture) on the No. 1 Haneda Line, where bridge renewal work is underway.
The bridge is currently under construction to replace the existing bridge girder with a new one, and the Haneda Line Heiwajima Exit and Tokai JCT to Yokohane Line Daishi Exit will be closed to traffic for two weeks from May 27, 2023 5:00 to June 10, 2023 5:00 (see related article “Metropolitan Expressway Daishi Bridge Renewal. Haneda Line closed to traffic all day for two weeks. Traffic congestion of up to 150 minutes is expected from Namamugi JCT to Daishi Exit”).
Since its opening in 1962, the Metropolitan Expressway network has gradually expanded and now boasts a total length of approximately 327.2 km. However, about 20% of the expressways have been in operation for more than 50 years, and more than 60% (about 217 km) for more than 30 years, and damage due to aging has become noticeable. Therefore, as part of the “Expressway Renewal Project,” large-scale renewal projects are underway for approximately 8.5 km of the No. 1 Haneda Line, No. 3 Shibuya Line, and Central Tokyo Loop Line, and large-scale repair projects for approximately 55 km of the No. 3 Shibuya Line and other lines.
The replacement of the Daishi Bridge is part of this effort. Since the bridge was built when it opened in 1968, it is aging, and due to the high volume of passing traffic and structural weaknesses, more than 1,200 fatigue cracks have developed across the entire bridge, necessitating drastic measures. For more details, please refer to the past article “Metropolitan Expressway Daishi Bridge to be Widened for Easier Driving! I observed the transportation and rotation of bridge girders to be replaced as part of the renewal project.
At the time of the interview for this article (May 2022), the installation of the new bridge girders was underway, and about a year has passed since then. The main event, the relocation of the existing bridge girder and installation of the new bridge girder, is just around the corner.
Prior to the press opening, Mr. Takayuki Noami, General Manager of the Project Promotion Department (Kanagawa and Saitama Regions), Renewal and Construction Bureau, Metropolitan Expressway Company, gave an overview of the construction work. He began by saying, “We apologize for the inconvenience to the customers using the Metropolitan Expressway and the residents living near the closed section,” and asked for their understanding and cooperation in the construction work.
The Highway Daishi Bridge was built in 1968, and “55 years have passed, which means that the bridge is aging,” he said, explaining that “the bridge is under severe use with approximately 80,000 vehicles per day,” that “the distance between the piers is long so that the flow of the Tama River is not blocked,” and that “the economic design of the time made the bridge lighter, so it is prone to bending. The bridge is now in more than 1,200 nonworking locations. He also stated that the bridge was designed to be lightweight at the time, which caused it to flex easily. As a result, more than 1,200 nonworking cracks have now occurred, and although daily inspections and maintenance are being conducted, new fatigue cracks have been observed, leading to the decision to rebuild the entire structure to “ensure its long-term safety.
The section to be renewed is a steel bridge section of approximately 300 m (292 m), weighing approximately 4,000 tons, “almost the same size as the Tokyo Tower. The bridge piers are also being strengthened by replacing the I-shaped piers with gantry piers. The sections before and after the bridge are made of concrete, so “daily inspections and repairs will be sufficient,” according to the company.
© Source travel watch