a second agreement in 1874 saw the b&m agree that its own merthyr branch from morlais to rhydycar junction become a joint line with the l&nwr, with the larger company taking advantage of the smaller company's financial state and repaying half the costs of construction at £25,000 per mile - far less than it would have needed to pay for access to merthyr. to reach the b&m's morlais junction, a short section long, partly in a tunnel, was constructed from penywern, just north of ivor junction. the link opened on 9 june 1879 and services ran through to merthyr (high street) using running powers over of gwr track from rhydycar junction. the junctions at merthyr and dowlais gave the l&nwr access to a number of local industrial tramways, including that of the dowlais ironworks to which it was later to build a more direct connection with the cwm bargoed mineral line.