At Thornton Junction (GTW MP 25.2), there is a flat crossing with the UP (ex-C&EI) line, and a connector in the northeast quadrant from that line to the GTW line heading east (and the CSX line sharing the track from this point), with extra track on the northeast side of the connector, where Amtrak's Cardinal. finally attains its southbound CSX (former Monon) route towards Lafayette, IN.
The double track joint segment with the GTW, speed limit 65 mph for passenger trains, 60 mph for intermodal trains, and 55 mph for general freight trains, heads southeast, has a signal bridge at the east end of the connector (MP 25.53), several grade crossings over north-south streets, a highway bridge overhead, a dual highway bridge overhead (I-80/94), a grade crossing with a north-south street, a grade crossing with an east-west street, past Oakdale, a cemetery on the north side, a grade crossing over an east-west street, a grade crossing over a north-south street, apartments alongside, a grade crossing over an east-west street, a grade crossing over a north-south street, apartments, housing, a grade crossing, the Illinois/Indiana line, and a golf course on the north side, to Maynard (CSX MP 25.5)/Munster (GTW MP 31.1).
Here the north-south Monon line once crossed at grade, and in 2006 there is a connector in the southwest corner of that former crossing, where the CSX line turns away south and the GTW line continues east-southeast. The PRR Chicago to Cincinnati line, that once used the north side of Chicago Union Station, once crossed the Monon and Airline Junction (CSX MP 25.4) and the GTW on the east side of its Munster, just east of the Monon/GTW flat crossing.