The R&SBR line and the GWR (L&OR) line ran parallel and adjacent from Cymmer to Blaengwynfi. In 1960 expensive repairs to Gelli Tunnel and Groeserw Viaduct on the R&SBR line became necessary, and instead a connection between the two routes was made, enabling trains on the R&SBR route to use of the GWR line, by-passing the defective section, which was closed. The L&OR line was connected into the R&SBR station, and east of the station a slue was made back into it. A new junction was made some distance west of Blaengwynfi, where the two routes separated once again. The new arrangement was commissioned on 13 June 1960.