The Merthyr Tramroad (sometimes referred to as the Penydarren Tramroad due to its use by Trevithick's locomotive built at that ironworks) was a 9 miles long line that opened in 1802, connecting the private lines belonging to the Dowlais and Penydarren Ironworks with the Glamorganshire Canal at Abercynon, also serving the Plymouth Ironworks along the way.