Post-Tensioning Tendons for a new Railroad Bridge on the Nambu Line
In order to save time and minimize cost, it is quite common for extensions of the Japanese railway system to incorporate gated at-grade crossings for road and footpaths.
In the past few years the Japanese railroad company JR East Japan Corporation has worked to eliminate traffic tie ups and increase safety by the increased use of bridges as grade separation structures.
From 2002 to 2005 a total of 15 level interchanges were redesigned over a length of about 4.3 km on the Nambu line between Inadazutsumi and Fuchuhonmachi. The removal of five at grade interchanges was even stipulated in the town planning act.
One bridge built as part of this project is the nearly 60 m long Yanoguchi bridge that was erected at the site where the Nambu line crosses the Tsurukawa expressway. This bridge across the Tsurukawa expressway was designed as a Langer bridge. As the bridge is located in an urban area, prestressed concrete was selected as the construction material to reduce vibration and noise.
To enhance the service life of the Yanoguchi bridge its deck was transversely prestressed using epoxycoated DYWIDAG Prestressing Strands. The bridge was constructed using fixed scaffolding systems. A special feature of the bridge construction was the continuous maintenance of traffic volumes on the railroad line and on the expressway during the construction work. To maintain sufficient overhead clearance during construction the bridge was constructed approximately 2.2 m above its final position and then jacked down after completion.
The bridge was opened to traffic in summer 2005 and takes trains of the Nambu line safely across the Tsurukawa expressway.