8B USD for 11 miles
CACHSR IOS 36B USD for 171 miles.
The Merced to Bakersfield IOS looks like a bargain on a distance basis. I have no idea of the carbon offset or passenger time saving versus flying of course
Fehmarnbelt tunnel sections are concrete. I couldn't find how they are connected by concrete would make sense.
The Transbay Tube sections were built in the Bethlehem Steel shipyards in San Francisco. A museum opens this month to commemorate that shipyard. It's in Dogpatch in SF, if you know the area. The shipyard still has a submersible drydock, but it hasn't worked in ten years and will be demolished soon, hopefully before it sinks.
The SF Bay Area once had far more heavy industry than most people realize.
I'm curious what the lifetime of those gaskets might be and how you might maintain them.
(german source ... and very critical of the project)
https://www.nabu.de/umwelt-und-ressourcen/verkehr/verkehrsin...
Personally I like the concept of having a more direct access to scandinavia and see lots of other positive long term effects.
https://www.latimes.com/california/story/2026-05-07/los-ange...
[0] https://www.trelleborg.com/en/marine-and-infrastructure/medi...
[1] https://www.trelleborg.com/marine-and-infrastructure/-/media...
[2] https://www.sciencedirect.com/science/article/abs/pii/S08867...
[3] https://dailygalaxy.com/2026/03/rubber-used-in-undersea-tunn...
This is a tunnel for Sweden, Norway and Copenhagen, it's moving the center of everything in Denmark closer and closer to the center of Copenhagen, completely disconnecting the rest of the country. A few days ago a new train start running Copenhagen to Oslo, a seven hour trip. That's the same time it takes me to get to Copenhagen by train within Denmark. Everyone is happy that you can "Get on the train and just pop to Hamburg, Berlin or Prag", but you can't, only if you happen to live in a few select spots does that work. It's a multi-day journey with a layover within the country if I want to leave by rail.
Internationally this is a great project, internally in Denmark, it's going to make international train travel worse for the majority of the country.
And then there is this tried and true tradition of commissioning studies with the sole intent to support a predefined viewpoint rather than taking an unbiased approach. This makes it so hard to trust any information when political arguments become heated.
To make the connection back to the tunnel: it consumes a huge amount of concrete and that releases the associated amount of CO2. Thisnpart is fairly easy to estimate. But estimating the impact on traffic emissions is fraught with issues. There are so many assumptions about lifetime, amount of traffic, types of vehicles that I can easily imagine the error bars to stack up to the point where a little tuning of model parameters gives just about any desired result.
> completely disconnecting the rest of the country
If there's some secret plan to demolish the bridges to Fyn and rip up the roads and railway tracks on Jutland do inform us.
Otherwise, the Århus to Hamburg train will continue to exist.
> It's a multi-day journey with a layover within the country if I want to leave by rail.
No, it isn't.
The first tunnel segment of the Fehmarn Belt Tunnel has been successfully immersed. This marks an important milestone in the European mega-project connecting continental Europe and Scandinavia.
With a length of 18 kilometres, the Fehmarnbelt Tunnel is set to be the longest immersed tunnel in the world – over three times as long as the current frontrunner the 5.8-kilometre Transbay Tube in San Francisco.The immersion of the first tunnel element on the Danish side of the Fehmarnbelt Tunnel is an enormous operation that has been prepared in detail and requires extensive expert knowledge.
Engineers from several European countries are working closely together through the RAT Joint Venture of technical consultants, bringing together the complementary expertise of Ramboll, Arup and TEC. The RAT Joint Venture has been working with the client Sund & Bælt since 2008, providing expert advice in a range of technical disciplines.
The 18-kilometre-long Fehmarnbelt Tunnel provides commuters with a much faster and weather-independent journey. The tunnel is designed as a highway and a double railway, making the switch from freight lorries to environmentally–friendly trains much more attractive.
The Fehmarnbelt Tunnel will complete the high-speed rail connection between Stockholm and Hamburg.
There are three important civil engineering contracts for the Fehmarnbelt Tunnel, each to be considered a separate project.
The TPR contract (Tunnel Portal and Ramps) focuses on the tunnel entrances and approach structures. It includes the cut‑and‑cover sections, the portal buildings, and the access ramps, forming the crucial transition between land and water in the polder area.
The TDR contract (Tunnel Dredging and Reclamation) covers the preparation of the site. This included dredging the tunnel trench—now completed—as well as creating land reclamations, building temporary working ports, and rerouting the sea dike to make construction possible.
The TUX contract (Tunnel) involves the immersed tunnel itself. Tunnel elements are constructed in factories on land by contractor Femern Link Contractors (FLC), then transported via basins to the working port. From there, the elements are towed to their final position and carefully lowered into the prepared trench.
The numbers