Actually, the tunnel itself was only 17 years:
1998: Start of construction of the Koralm Railway
2008: Start of construction of the Koralm Tunnel
2018: Breakthrough Koralm Tunnel
2020: Final Koralm tunnel breakthrough
2025: This announcement (https://orf.at/stories/3414173/ in German)
https://infrastruktur.oebb.at/en/projects-for-austria/railwa...
Given the terrain and the amount of tunneling needed, completing such a project in 17 years isn't that bad.
Seems software neckbeards on HN are equally as guilty of underestimating the difficulty of other people's work like the managers they complain about.
Yeah, the submitted page misses the real news: Ordinary traffic will start tomorrow, Sunday.