From the wye junction that the GWWR calls Church (MP 287.2), on the northeast side, with the Alton & Southern line to its Gateway Yard (and onward to Granite City) and the Cotton Belt's Valley Yard, both of which run parallel along the north side of the line, and continues northwest along the south side of the Gateway Western yard in E. St. Louis, the Two Main Track line, with Track 1 in Yard Limtis and Track 2 CTC, continues northwest, past flat crossings with an Alton & Southern connector and then the UP/SP (Cotton Belt)/TRRA main line at Valley Junction (MP 283.6)—these mileposts are from Chicago via the former Alton/GM&O/ICG, and now SPCSL—the two tracks separate, and Track 1, in Yard Limits, and continues northwest, past a former west quadrant connector with the UP/SP (Cotton Belt) line southwest, a former flat crossing with an erstwhile Alton & Southern line, and a former flat crossing with the erstwhile East St. Louis, Columbia & Waterloo interurban.
The line turns north-northwest, and then north, passing beneath the eastern approaches of the MacArthur bridge, and then passing the location of a former flat crossing with an erstwhile Southern line to the east bank of the Mississippi River, and the former location of an erstwhile crossover with Track 2, running parallel about a quarter mile further east, then splitting in two at M&O Junction (MP 282.1/TR 1.1), where ownership passes to the TRRA, with a connector turning west-northwest to a TRRA line to the riverbank (and once also continuing ahead to the erstwhile M&O Yard), the northeast approaches to the MacArthur bridge passing overhead, a connector from a TRRA line from the south trailing in on the west side as the line turns northeast alongside the descending bridge approaches, a former connector west into the erstwhile IC yard towards the river, Trendley Avenue (MP TR0.7), where Track 2 trails in on the east side, and once spawned a connector westward that made a flat crossing with Track 1, and runs parallel to Track 1 as both bridge over the St. Louis Metrolink light rail line, to Q Tower (MP TR0.0/281.0).
At Q Tower (MP 281.0), the TRRA Yard Limits single track line coming northeast from M&O Junction (and the TRRA CTC single track line coming north from Trendley Avenue) join with the Two Main Tracks, Traffic Control System, line northeast from the TRRA MacArthur Bridge District, where a number of lines coming east from the river bank used to cross at grade, and today's line splits into a TRRA line heading north-northwest to Bridge Junction, a TRRA line heading north-northeast (the Eads Conologue District), a Gateway Western (formerly PRR) line heading northeast and a CSX (formerly B&O) line heading northeast, all past the former location of Relay station just north of Q Tower.