A bill was presented to Parliament in January 1793, but after its second reading, the Monmouthshire Canal succeeded in making an amendment, for a somewhat different route which had been surveyed by his brother Thomas.
Although no work on the canal had started, the company began building the Clydach Tramway, with Dadford as engineer.
It is difficult to be certain which sections Dadford was responsible for, with Hadfield describing a tramroad from Gelli-felen colliery to Gilwern, which then crossed the River Usk to reach Glangrwyne, where iron from Ebbw Vale was worked in a forge[3] Skempton describes a 5.5-mile (8.9 km) tramroad from Llangroiney [Glangrwyne] to Gellifelen, and a second section from Gellifelen to Fossalog, near Nantyglo,[2] while Gladwin and Gladwin describe a 1.4-mile (2.3 km) route from Llammarch Colliery to Clydach Ironworks.
The committee were critical of the Dadfords, but when they called in William Jessop to advise them, he suggested that such issues were merely teething problems, and were quite normal on such a project.
Despite the failure of some of his bridges, he was highly regarded, with the Monmouthshire Canal requesting that if anyone was sent down to inspect the works, they would prefer John Dadford to anyone else.