Where would I find typical concrete column tolerances for bridge column tolerances? These will be about 6' tall, rectangular in shape. Rail application.
It has a section for cast in place bridges. Not sure if there's anything specifically about rail, but I would think the only thing that matters there is the rail elevation, slope, and alignment - as long as those meet the railroad's specs and the structure is designed to carry the loads and built to whatever tolerances the engineer chooses, I don't see why it would be a problem. But I've never designed a rail bridge, so take that for what it's worth.
American Railway Engineering and Maintenance-of-Way Association (AREMA) "Manual for Railway Engineering" covers essentially all aspects of work on railroads.
Check with the railroad company, some have their own specifications.