In 1834 Bald had the idea of opening up a limestone quarry on the Cavehill, near Belfast, and transporting the stone down to Belfast Harbour by a railway. He estimated the work to cost £12,000, but thought it would deliver an annual income of around £2,300. The Cavehill Railway and Quarries company was formed and Bald constructed a double track tram road of 4' 9 gauge, operated by horse and gravity. The track crossed the Ballysillan Road under a twin arched bridge, crossed over the Antrim Road and ran down to the port by way of the Limestone Road. The company continued to trade until 1896 when it became bankrupt.