As a side question... it seems like this work has been going on for years now... and it has. When are we going to see more than just 18 miles of 110mph trackage? I have searched for an actual timeline without success,
While IDOT doesn't provide a specific answer, browsing through a number of online articles would indicate that one could expect 110-MPH max speed available on the Lincoln Service, from Joliet to Alton, anyway (save for Springfield), to begin in Fall, 2017.
In addition to the track work, there is also bridge work (the Kankakee River bridge in Wilmington comes to mind), and many at-grade crossings that require upgrading, along with quad gates and perimeter fencing.
There are a number of stops along the line that are receiving new stations or upgrades to current facilities. New stations are being constructed in Dwight (to be completed Fall, 2016), Pontiac (to be completed Fall, 2017), and Alton (Good luck, Alton. They received a $14 million TIGER grant in 2011 for the station. The money must be spent by December 31, 2016, and I don't believe brick one has been laid.). Joliet should have the rail portion of its multi-modal station completed by Fall, 2017. Lincoln restored its historic depot to its original footprint and Iowa Pacific removed several vintage rail cars to de-clutter the area. Lincoln officials are finalizing details on enhancing the depot and passenger amenities; completion is expected Spring, 2017. Normal is in the process of adding a second platform and some improvements to its waiting room, to be complete by March, 2017. Springfield's station is due for some unspecified improvements. Carlinville has plans for a new depot, but no money at the moment to put those plans into action.
Delivery of the Siemens Charger locomotives are scheduled for 2017. The new Nippon Sharyo bi-level rail cars were scheduled for 2017 delivery as well; of course, we all know how THAT has been turning out.
So, adding all that together, it seems as if IDOT's strategy has been to flip a switch, so to speak, in Fall, 2017, providing what is hoped to be a greatly improved rail experience all at once, as opposed to less noticeable incremental improvements.
Unfortunately, progress on the Tier 2 EIS reports for both the Chicago-Joliet and Granite City-St. Louis segments are currently on hold, possibly enjoying the same "under review" development hell that Rauner has placed the Rockford and Quad Cities corridors. If November's elections provide the nation with a more rail-friendly President and Congress, IDOT won't be ready to stand in line for the cash.