Interestingly the ferry which is currently used to transport trucks is only at roughly half capacity.
It is a prestige project and I will have to move to some other place as I live next to the train tracks. These are used very sparingly today and are mostly not even electrified and one-tracked. Many wildlife refuges are on the way to move for the sake of the new tunnel.
Sometimes the existing solution doesn't need to be bursting at the seams to justify building something better. A better solution can induce its own demand.
By distance from Malmö to Hamburg is a bit farther than to Gothenburg and Berlin is a bit closer than Stockholm, with the forced dogleg of going through the Fehmarn Belt. By air it would be like Leipzig. That is how far into Germany you get.
It is simply ridiculous that the only way I could think of to get to the larger cities in northern Germany would be to fly. Take the train to Copenhagen airport and likely Ryanair or something similarly awful costing less than the ticket to the airport.
Sure I could look up some train travel with a multitude of changes through Denmark, likely taking the train on the ferry. Or an over night sleeper style, if they even run. I know there's been talk of them starting again.
It's 2022, there should be high speed links.
The new-ish night train runs direct from Malmö, but only in some months of the year. (A seats-only overnight train runs all year from Copenhagen. But that was not fun the one time I used it.)
There's a rail noise map for some lines in Denmark. Activate Temavælger - Jernbanerstøj - Større Jernbaner 1,5m, and start at Copenhagen Airport, the Øresund line might be similar.
In Denmark this project would have been built in a year, in time and in budget. But unfortunately this involved Germany, so now they have another huge stinking overcost project. Denmark is angry
About construction delays and politicians getting in the way etc., I can only think of BER as a catastrophic project. Do you have more in mind?
In Cologne a tunnel collapsed during construction, killing two people: https://en.wikipedia.org/wiki/Cologne_Stadtbahn#Tunnel_colla...
https://www.tunnel-online.info/en/artikel/tunnel__3596417.ht...
But apparently it's again stopped: https://www.dredgingtoday.com/2022/01/19/leipzig-court-tempo...
Overview: https://en.wikipedia.org/wiki/Fehmarn_Belt_Fixed_Link
There should be better articles about the cost overruns.