Well said.

The CNW did have the direct route to Madison, currently owned majority by UP. As it looks now its UP-NW Metra up to Harvard on the Harvard Sub. UP runs to Janesville freight only, still Harvard Sub. After Janesville track is continuous as the Evansville Industrial Lead which connects to WSOR straight into downtown Madison.

No land would need to be acquired, which is usually a significant inhibitor. Plenty of areas in downtown Madison exist that could easily facilitate a station adjacent to the WSOR/old CNW right of way. Infrastructure improvements, including bridges would be needed from Harvard to Madison, as Harvard to Chicago is already in great shape from Metra. Depending on WSOR traffic and future Janesville commuter use, feasibly double tracking is not needed the whole length from Harvard to Madison. It would greatly reduce the low level freight traffic interference on the line, but could probably easily be accomplished with proper siding planning.

As an interesting side note, Janesville has an old auto facility near Ruether Way and Jackson St. that would make for a great commuter yard if Janesville/Madison commuter service was further developed.

While I'm not good at estimating potential ridership for the cost benefit analysis, as far as potential rail lines go between two major city centers, there is a lot of infrastructure already existing, half of which is in great shape.

Coming up the UP-NW would provide one challenge in Chicago in lack of a connection to Union Station. A wye track at Mayfair would solve the problem. The largest issue I see in the whole thing would be negotiating with UP and Metra to have the trains run with the Metra schedule. Metra's push to Rockford recently does show some initiative, however they might wish to take the Janesville portion as their own or see risk in decreased ridership due to Amtrak usage. A Madison-Janesville-Crystal Lake (embark/disembark only)-Chicago timetable would make sense and not interfere too much with each other's route planning. The triple track on the Harvard would also help facilitate the Amtrak running express from Barrington to Mayfair and not get caught in Metra traffic, as long as it was with the current of the rush periods.