The branch line to Neath Colliery left the main line at a junction just to the north of Neath Station. Construction of the branch was complicated by the fact that the mine itself was situation at the top of a hill.
The branch to Neath Colliery original extended from near Abermain Station. When the main line was duplicated in 1909, most of the siding became the Up Main and the junction moved just to the north of Neath Station. A trailing crossover was installed south of this. This made for a time-consuming forward-reverse-forward movement to enter the siding. In 1975 a facing crossover was finally installed on the up side of the branch junction to remove this source of congestion.
The mine opened in 1907 and operated until December 1984. The branch remained in use until the coal washery closed in April 1988. The line was lifted shortly afterwards. Neath was the most recent closure of the South Maitland Railways (only the colliery at Pelton remains open).