 Greaves had a history with the slate quarries at Blaenau Ffestiniog, and had proposed a railway to link the quarries with the river wharf at Dwyryd as early as 1836.When the Ffestiniog Railway was opened in 1836, connecting Blaenau Ffestiniog with the sea at Porthmadog, Greaves travelled on the historic first train.In 1843 Greaves was elected the treasurer of the Ffestiniog Railway and in 1844 he became its chairman.