the first sod was turned at abergavenny on 18 june 1860 at the brecon new road by crawshay bailey's wife. work commenced immediately on the line's construction, the contract for the section between abergavenny to brynmawr having been let to william mccormick. a report by chief engineer john gardner in june 1861 gave an upbeat account of progress: the road and railway bridges along the track route were under construction and nearing completion in the lower abergavenny section, cuttings were being excavated and embankments established between abergavenny and brynmawr. rail had been laid where possible and an engine mounted on the tracks to further facilitate the speedy transport of construction materials to the section being laid, with work at this point focusing on the embankment between the monmouthshire and brecon canal, the river usk and the trackbed at gilwern.