Amtrak plans for substantial speed upgrades on the NICTD from Michigan City as far as Hegewisch. Lengthy stretches of 90 to 110 MPH. Probably raised speeds east of Michigan City as well, I haven't come across any detailed plan for that yet.
The curves from Gary to Kensington cannot be improved significantly. And don't underestimate the potential delays at Kensington.
Even if Amtrak relaid the NYC from Englewood to Whiting, that does nothing to resolve the freight interference from there to Elkhart. Those delays alone likely exceed any problematic curves on an upgraded NICTD-- and at any rate Amtrak's engineering department has already done the calculations to show it!
Agreed. The South Shore Line should be a faster route from Gary through South Bend. It's only possible once the South Shore Line finishes their double tracking project (still in progress); trying to fit Amtrak in on the single-track line would have messed up the schedule way too badly.
Unfortunately, the currently-funded double-tracking is only as far as Michigan City; so the Michigan trains could use the South Shore Line as soon as it's done, but the LSL and CL can't until double tracking is done from Michigan City to South Bend.
Unfortunately, a lot of NS's dispatching mess is *east* of South Bend, for which none of this will help. The extension of passenger-exclusive tracks to Elkhart would be necessary, and probably further east, too.
Anyway, buy the tracks whenever possible...