Maybe this thursday new DLC will be released for SPG route. For now there is already extra layer in SPG timetable so there is a chance to use it now. Here is mod which unlock 10 extra services for C40-8W. This mod dont require any extra DLCs as services are added to the 4400 loco for now. List of the services you can see on the screen. You can download that mod here: http://www.trainsim.cz/?mod=article&showid=2422
Interesting. 10 services that's part of the Dash 8 add-on (and some say there weren't gonna be any extra services). One 4-part to/from Shaw Mine and the rest are just through trains. Very interesting indeed.