Basically the idea is simple,
*allow our sims to do modification to cars (tuning), custom race stripes
*add railways and functional trains to the game
=> New Job railway worker, that branches at lvl 5 to either => train conductor(lvl10)
=> railway ceo(lvl10)
*update WA neighbourhoods, if WA detected, to include train links, and let sims travel by train to those destinations, for instance TGV to France.
*trains drive at fixed schedules on the map, but work more or less like subway, maybe with a visible train transporting the sims
*new trait: public transport minded, sim prefers to take public transport, gets mood bonus when taking public transport to work or relax area
*add industrial work branch (constructing new cars/trains) with branch at level 3 to either => crew chief(lvl10)
=> company ceo(lvl10)

*train station rabit hole/train station rabit hole with underground connection
*new neighbourhood with lots of train activity
(*new sub neighbourhood to travel to by train)

*update to create a world tool to allow the creation of railways in our neighberhoods

Very cool ideas!!! That'd be somthing cool to throw into an EP. Sadly, I doubt somthing like that will emerge, with the City (Late Night) EP already released :/

I could see railway being added into the game but I don't think that EA will give us something along the lines of an update to the LN subway system. This is what I'm thinking how it could work:

- I would like to expand on your idea about the train connecting to the WA places... I would also like to see it connect to the other neighbourhoods if you have created save-files for them as well. So you could send your families to Riverview (or wherever else) and have them spend a couple of days there in a hotel or at a friend's place. The trains also operate on a fixed schedule like you said.

- When you travel to another neighbourhood, that neighbourhood will operate the way it is set-up when you legitimately play that neighbourhood. Say if you send someone from Bridgeport (which isn't using story progression) to Riverview (which is using story progression), while you are in Riverview the neighbourhood will operate like it is on story progression until you return to Bridgeport.

- The train station is essentially a rabbithole. Sims come here to travel, order items from other neighbourhoods, or ship off gifts to relatives.

- As for the new careers that you mentioned... I agree with them. Up until level 5 they can either be a transportation business wo/man or a train operator.

- I think that the train operator branch could be an Ambitions-like career. They have to maintain the train's repairs, collect items to ship off to new places, receive items from other worlds, and convince people that they should travel by train to somewhere new.

- No new traits in regards to transportation. Maybe an update to Eco-Friendly sims?

These are just some ideas to bounce around though..

Interesting ideas. I like it.