According to wikipedia
"Japan and the Soviet Union ended their formal state of war with the Soviet–Japanese Joint Declaration of 1956 but did not sign a peace treaty."
It's a little awkward, but what it's trying to communicate doesn't really work well in one sentence.
As a native US English speaker, I would probably write something like "Austria opens the world's sixth longest railway tunnel: 27 year long project arrives on schedule and under budget."
https://hn.algolia.com/?q=https%3A%2F%2Fplato.stanford.edu%2...