[3] The Dinorwic slate quarry was purchased in 1809 by a group of investors led by Thomas Assheton-Smith and a significant expansion was started.
Until 1812 slate for sale beyond the locality was sent by packhorse ("hampers on horseback") then sometimes by boat across Llyn Padarn then by cart to Caernarfon to be forwarded by sea.
This slow, labour-intensive process could cost more and take longer for the seven miles from quarry to shore than from Caernarfon to Liverpool.
The new railway followed the general route of the Slate Road from the highlands of The Braich[6] northwest to near the coast, where it swung west to approach the creek on its northern side.
The inclines were "balanced" and "self-acting", i.e. the extra weight of a descending rake of loaded wagons lifted a corresponding rake of empties, with the rope, cable or chain passing round a braked drum to enable staff to maintain control.