Hallandsåsen in south Sweden there is a lovely trainride around the hill. There is planned a tunnel which will shorten the trip with 8-10 minutes.
The planned length is 8.7 km (5.4 mi) (8,722 metres (28,615 ft) in one bore, 8,710 metres (28,576 ft) in the other).
The project was started in 1975 and is still not finished and there were a
scandal when dangerous sealant materials were used causing workers to become ill and killing local fish and cattle. As the hill is not compact stone but enourmous stones it can any time collapse. The water from the wells was running thru the stones down into the tunnel
The cost 2 billion USD as calculated in 2008, before the project is finished. Don´t want to know the costs now.
Here they drill