Most CSX freights through Pittsburgh do not run through the city itself on the former B&O, but bypass the city to the south and west by means of the former Pittsburgh & Lake Erie. This leaves the main line at New Castle, then crosses to the west side of the Ohio River at Beaver Falls, some 25 miles from Pittsburgh, runs southeast past downtown along the Ohio River and then Monongahela River, and eventually crosses back to the east side, rejoining the former B&O in the midst of the steel mills at Braddock.
The former B&O jogs to the south to pick up the double track route of the former Pittsburgh & Lake Erie, coming across the river from the west to a junction and crossover at Rankin-Braddock (MP 319.0/9.1), on the river side of a portion of the Edgar Thompson Works at Braddock. The Union Railroad connector crosses above(?) the line and heads across the river to the southwest bank, while the P&LE route continues southeast along the northeast bank, with speed limit 35 mph, past Port Perry (MP 10.5), under the bridges carrying a Union Railroad line and the former Conrail Mon Line across the river and east to the ex-CR Pittsburgh line on the hillside to the east, past the Union Railroad yard on the east side of the line Demmler (MP 11.6), where a 12,600 ft. siding begins, there is a crossover and the north end of the Demmler Yard along the east/south side of the line that now turns south and then west to the south end of the yard at a signal bridge and grade crossing at Riverton (MP 14.3), where both siding and yard end, the speed limit drops to 25 mph, and a line trails in from the northeast (i.e., on the "west" side of the line), across the river. There are signals "east" of the junction, a grade crossing, a street alongside to the south/east, and a grade crossing.
The line passes McKeesport (MP 15.3), where the line crosses the Youghiogheny River mouth on a through truss bridge (as the line turns), the ex-P&LE Mon subdivision continues straight ahead on a different bridge, and the Pittsburgh subdivision, with speed limit now 30-25, turns south, and then south-southeast, along the west bank of the Youghiogheny, with a street alongside to the "east", i.e. between the line and the river, past Port Vue, an acute angle grade crossing, a road bridge overhead (and across the river), and extra track on the river side, trailing in, to reach B&O Junction at Sinns (MP 16.8), where the connection to the original route of the B&O heads east across the river on a deck girder bridge to pick up its original route.