Explanation

• The largest undersea railway tunnel is constructed between France & England
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• The largest undersea railway tunnel constructed between France & England is the Channel Tunnel 
  
• This tunnel was built in 1988.
• The length of this tunnel is 31.4 Miles.
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• The project to build the undersea leg between England and France began in earnest in 1986.
• But as work progressed, the owner, Eurotunnel, and the Anglo-French consortium responsible for the design and construction