Japan was the first country to build dedicated railway lines for high-speed travel. Because of the mountainous terrain, the existing network consisted of 1,067 mm (3 ft 6 in) narrow-gauge lines, which generally took indirect routes and could not be adapted to higher speeds. Consequently, Japan had a greater need for new high-speed lines than countries where the existing standard gauge or broad gauge rail system had more upgrade potential.
The Shinkansen uses 1,435 mm (4 ft 8 1⁄2 in) standard gauge in contrast to the 1,067 mm (3 ft 6 in) narrow gauge of older lines. Continuous welded rail and Swingnose crossing points are employed, eliminating gaps at turnouts and crossings. Long rails are used, joined by expansion joints to minimize...
more... gauge fluctuation due to thermal elongation and shrinkage.
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