It can without internet for 30 days, but then you must connect to the internet to make a phone call to home and to receive any updates.. so really TRS19 is not made to run offline, and I don't think DRM free won't come until demaind is high, like extremely high.
If you want to run Trainz offline completely, I would've recommend TANE, but since they aren't selling box versions anymore (well, you can search on 3rd sellers anyway)..
Cheers