 During duplication an additional signal box was opened at Neath.Additional signal boxes were later opened at Mt Dee, Bee Siding, Aberdare South Junction, Aberdare Central Junction and Bellbird Junction on the main line, and Kalingo Junction on the Kalingo branch.The Bellbird branch from Bellbird Junction to Bellbird Colliery, and the Pelton branch from Bellbird Colliery to Pelton were worked by electric staff instruments.