I've seen an NJ Transit loco operate to and from the quarry. Usually around midnight, they will run a train across Rt 22 into the quarry. Although the 22 crossing is signaled, there is always a flag man. The stone cars are also stenciled NJT.
On a tangential note, the quarry is on the site of one of the key defensive positions of the Revolution. When Washington was in Morristown, Continental pickets held Chimney Rock pass against the British, who occupied New Brunswick. The quary has basically chopped down the 400 foot hill that kept the British at bay for half the war. And just about a mile further east is the site of Middlebrook encampment, where the Stars and Stripes flew for the first time. So endeth today's history lesson.
"One tequila, two tequila, three tequila, floor." George Carlin