Today I am suggesting the Washington Metro Yellow Line from Pentagon to L’Enfant Plaza. The characteristics that make this route unique are that the Yellow Line is the only line on the DC Metro to cross over the Potomac River on the Charles R. Fenwick Bridge and it is one of only two sections of track that is not shared with any other lines. This route would be fun because the gradients/curves make for a challenging drive that keeps you focused. The trains that run on this route are: Alstom 6000 Series Kawasaki 7000 Series Hitachi 8000 Series
I would recommend a read of the advice on making suggestions. https://forums.dovetailgames.com/threads/matts-advice-on-tsw-suggestions.86336/ An AI summary isn't really enough. I'd also suggest searching the forums to see if your suggestion has been discussed previous, I seem to recall a number of threads regarding the Circle Line/Hammersmith & City Line. It's also worth noting that there were severe difficulties with the London Bakerloo Line DLC which makes it very unlikely that we'll see another predominantly underground line from anywhere in the world.
Yes. Well, you are pitching an idea to a business. The more eye-catching, detailed, realistic and compelling you make it, the better chance you have of it getting noticed. My advice would be to pick one suggestion at a time and make it an interesting post for us all to read. Rather than just posting 10 new suggestions a day all with what looks like an AI summary, focus on one.