The quadruplication involved the relocation of the junction and the construction of a new signal box positioned above the tracks towards Macdonaldtown station, that was opened in 1916.

Further north is the Illawara Dive, where trains from the Illawarra line can crossover to the Main without obstructing any of the other tracks.

In the north-west corner, just north of Macdonaldtown station, there are a number of crossovers allowing trains to switch between the Local, Suburban and Main lines.

There are a complex set of flat junctions allowing trains on all three pairs of tracks to enter Sydney Terminal.

Eveleigh Maintenance Centre lies to the south of all the surface tracks and on top of the Eastern Suburbs line tunnels.

At various stages, especially during the early years of the 20th century, incidents occurred at the Illawarra Junction including the death of fettlers[6][7][8] and other railway workers,[9][10] and derailments.