An erstwhile former Southern line from the TRRA Wiggins #5 Yard and a former Southern location on the east bank of the Mississippi River below the current MacArthur Bridge once passed a flat crossing at Southern Crossing on the TRRA Eads Conologue District, passed beneath the east approach to the MacArthur bridge, turned northeast, and made flat crossings with the two former IC lines between their East St. Louis yard and Hole-in-the-Wall before reaching the current end-of-track on the Dyke Branch. Another erstwhile former Southern line left the cureent TRRA line off the MacArthur bridge in the opposite direction at the location of the erstwhile East St. Louis Union Station, curving south and then southeast, where the MetroLink light rail line now crosses the route, and made a wye with the line from Wiggins #5 Yard at 10th Street (MP 3.6), where the St. Louis District now starts.
The single track line heads southeast, Yard Limits, maximum speed 10 mph, past the west leg of the wye on the north side with the former Venice & Carondelet Belt at W-Line Switch Coapman Yard (MP 4.3), the east leg of that wye trailing in, the flat crossing with the TRRA Illinois Transfer District, with east quadrant connector at Southern Interlock (MP 4.4), another connector from the same TRRA district trailing in on the north side at TRRA Connection (MP 4.8), where Yard Limits end and Automatic Block Signals start, with the maximum speed rising to 20 mph, and the flat crossing with the Alton & Southern, with western and southern quadrant connectors at A&S Junction (MP 6.3), after which the maximum speed rises to 35 mph.