Hi,
The Rackville Bridge on the Pennsylvania RR (4 tracks and a mile long) was built about 1909 (IIRC). The PRR got the stone masons from Greece. Damned good work. I even met one or maybe the son of one. He ran the Studibaker dealership in Harrisburg in the 1960s. I think the first part of the Rockville Bridge masonry fell off about 2000. The Shocks Mill bridge (miles downstream on the Low Grade) had a few spans in the middle washed away due to a huricane (Agnes I think). The missing span was replaced by a stee truss bridge. Stone arch and steel truss - crazy what happens over time. All the bridges used no mortar or concrete (came to light when the first section of the Rockville bridge collapsed and the inside could be examined).
Stone masonry stands up to the test of time even though it is expensive.
Chinese were imported to build the Central Pacific also.
Maybe overseas is where to look - as an additional option. They have lower wages than ours also.
Doug vV