Hi HN, I'm Anton, founder of Luna Rail.

I've always thought night trains are a fantastic, sustainable alternative to short-haul flights, but they're often held back by a lack of privacy, comfort, and poor economics due to low passenger capacity.

I became overly fascinated with this puzzle. I view it as a kind of night train Tetris (my wife less charitably calls it "sardinology"). I spent way too much time learning about and sketching various layouts, trying to figure out how to fit the maximum number of private cabins into a standard railcar, while making them attractive for both day and night travel.

This eventually led to a physical workshop (in Berlin) and a hands-on rapid prototyping process. We've built a series of full-scale mockups, starting with wood and cardboard and progressing to high-fidelity versions with 3D-printed and CNC-milled parts, with various functional elements.

Hundreds of people have come in to test our various iterations, because you can't test ergonomics or comfort by looking at renderings (although we did create a bunch of nice ones).

The link goes to our home page showing our approach and some of the thinking behind them. It’s been a lot of fun working on this puzzle, and we're excited to share what we've come up with. We hope you think it's cool too and would love to hear your thoughts.

What do you see as the benefits over Nightjet’s Mini Cabins?

Also, interesting to see just after the launch of https://noxmobility.com/ which is targeting the same market.

  * night only
  * 40 pods per car
  * implemented

  * day and night
  * 65 pods or 40 single rooms
  * in physical, iterative development for more than a year
  * team focused on product development

  * day and night
  * virtual concept
  * team very strong on marketing

What's up with the super high carbon intensity estimate of your trains? Is it because they're running at night and can't use solar? Does it include embedded carbon in the train? Or is Germany's grid just that dirty?

I love the concept and the renders, but I wonder... is the spatial optimization really what's holding train travel back? If you decrease passenger density in order to increase privacy and comfort, do you then have a corresponding increase in ticket prices?

In places with good train travel, it seems like they already have several cabin classes, from sardine seats (still luxurious compared to air travel) to private cabins (at several multipliers of price). Pod style rooms would presumably be cheaper than that, but still a lot more expensive than a seat?

Then in places without high speed passenger rail, like the US, this wouldn't really be able to address the major problems with train travel (slowness, lower priority than freight, low reliability, etc.).

Under what scenarios would using pods instead of cabins be more economically viable? And could these be retrofitted into existing sleeper cars, or would they have to build entirely new trains?

I've long joked that modules should be made easy to swap with a forklift. Trains are usually full of small defects that aren't serious enough to take them out of service.

If they are comfortable you could rent out the cabins when not in use either fitted on the train or not. You could also retire the units there.

You could make a platform only and make it easy for others to design modules in a broad price range. Maybe most modules should be in storage until booked.

You could park the "hotel" module on the destination and put it back on the train for the return trip.