The Fehmarn Belt fixed link is an under-construction road and rail connection between Germany and Eastern Denmark.
According to the project website, it will be completed and open to traffic in 2029.
This question resolves to true if the project is officially completed before 2030 [1].
In the absence of an official announcement of completion, or in the event that the link is declared completed despite clearly not being capable of full-scale operation, I reserve the right to use a common-sense resolution criteria based on whether or not the link is routinely passable for regular road and rail traffic.
[1] As per the official time in Copenhagen
1,000I created a similar-but-different market that resolves NO as soon as delays to the completion date are announced: https://manifold.markets/ThomasTwenhoven/will-the-fehmarn-belt-tunnel-open-i
This seems interesting to me because it reduces the expected duration of capital lock-up.
Thanks to @kurgan and @marketwise for creating the other markets related to the tunnel project :-)