Deletion of Tunnel problem

Comment: Appears to be notable, concept discussed in books https://books.google.com/books?id=m28sDwAAQBAJ&pg=PA603https://books.google.com/books?id=N3QzDwAAQBAJ&pg=PT35 and other articles already mentioned. Should satisfy 
Stance: keep
Cited policy: Wikipedia:Notability (WP:GNG)