The tramway was worked as two distinct units, between the wharves at Porthmadog and Beddgelert Siding, and the quarry traffic beyond Beddgelert Siding, and the accounts were divided accordingly. Prior to 1872 the western section assumed great importance as it was the connection between the Festiniog Railway, the Ffestiniog quarries and the standard gauge railway, a significant volume of slate traffic was moved over the Tramway to Beddgelert Siding, and in the reverse direction was sent general goods and the coal for the locomotives at Boston Lodge. Much of this ended in 1872 when the exchange sidings at Milford were opened, giving the Festiniog its own interchange with the Cambrian (and later the arrival of the LNWR and GWR at Blaenau Ffestiniog further diluted this traffic). Incidentally the Tremadoc Estate objected to the Minffordd scheme as it would reduce their income from rates levied on tonnage on the FR and Croesor through Porthmadog. Even after 1872 much slate was transhipped at the Beddgelert Siding due to Minffordd yard being congested.
Slate traffic off the Festiniog would be worked onto the quays by the bottom shunter and then taken by horse through the streets to the Siding (there being no through route until the WHR link was built). An unexpected source of traffic in the reverse direction came from goods carried by the Cambrian that was destined to be loaded onto ships at the harbour.
Halfway between the harbour and the Siding was the Portmadoc Steam Flour Mill Company. Most of the flour from the mill was shipped out by sea and carried to the harbour on the tramway.
The eastern section provided slab and finished slates from the quarries along the Croesor valley, destined either for the Cambrian sidings or the quays. Inbound traffic was considerable and included timber, foodstuffs, coal, manure, lime and other materials as required for improvements and repairs in the quarries.
In a similar manner to the FR prior to 1863, the tramway did not provide its own horses. At its height, two hauliers would work the upper level and another two the lower level. Wagons were likewise provided from other sources as required, none being owned by the tramway. It appears that the FR was a regular source of wagons, particularly in the early years. Later the preference seems to have been for the quarries to provide their own wagons and also to hire them to the tramway for its own use, both New Rhosydd and Kellow being creditors for wagon hire at various times. Timber traffic was carried on FR bolster wagons, there being no alternative source.
Once the WHR link was in place, the horse traffic was restricted to the section of line east of Croesor Junction, possibly only beyond the Llanfrothen road crossing. The Baldwin petrol tractor (now 'Moelwyn') bought by Colonel Stephens was 'posted' (on paper only) to the Croesor Tramway and was used to bring runs of wagons down from the road crossing to the harbour, but this was unpopular with the FR as it left Minffordd yard without a shunter for lengthy periods of time. From 1926 an Austro-Daimler tractor was used regularly between Lower Parc and the harbour, being much lighter than the Baldwin.