tubechallenge.com

The Space Train and S-stock are entirely different concepts. The S-stock designed for the SSLs will have conventional carriages, but with continuous walkways between cars. The Space Train concept for tube profile lines was an articulated train, which is where car ends share a bogie, and the car lengths are much shorter (approx 11m instead of 15-18m). The shorter car lengths would have allowed for a wider car body, thus significantly increasing internal space. It would of course also have had a continuous walkway between cars.

Thanks for the info.

To try and save credibility, you'll notice I only wondered whether they were the same or similar, I did not state it!