The main points of the project:
- replacing the aboveground stub-end terminus with an 8 track underground through platforms
- new tunnels and tracks connecting the new station with the various lines entering Stuttgart, as well as new/moved stabling yards, and the new high-speed line via the airport to Ulm (partly finished since last year)
- around the station, some light rail, road and water tunnels had to be diverted and rebuilt
- new housing and parks are planned on the current railway land
- this + the existing S-Bahn tunnel are being equipped with ETCS Level 2 w/o signals and partly ATO
- new signalling means current trains are one-by-one upgraded resulting in old loco-hauled stock running as a replacement
- massively late and over budget (current estimate: December 2026 with some test trains earlier that year)
- massively controversial since violent clashes between protesters and police happened in 2010, and the subsequent close state referendum in 2011 that turned out in favour
- close to capacity already at opening
- the Gäubahn line (Böblingen/Singen/Zürich) will be unconnected to the new station for 7? years while the old line can't reach the new station and the new tunnel to the airport isn't ready yet. It's been replanned and the tunnel has not even started construction at the moment. Current timetable plans see Zürich IC and several RE in that direction terminate at Stuttgart-Vaihingen station in some suburb for those 7 years, with everyone asked to take the S-Bahn into town
Just like the Hamburg Elbphilharmonie and the Berlin BER Airport, this has become one of the big controversial construction projects that everyone has an opinion on.
The very uncomfortable and inconvenient station has been a meme for years. The long corridors through the construction site that lead from the platforms to the outside world and S-Bahn and light rail platforms have been dubbed "Fernwanderweg" - "Long distance hiking trail". Just as an example:
https://www.instagram.com/reel/C-DMrnnsfLV