I read from a few sources that the Steel was Fabricated by Phoenix Iron Co of Phoenixville, PA. Not sure if they erected it as well. Can anyone verify?
Shorpy has a large picture ca. 1912 from the LOC at:
Designed and built by Ralph Modjeski. Carries 4 vehicle lanes on upper level (2 each direction) plus 3 reversible lanes on lower level. 4 subway tracks on lower level plus pedestrian and bicycle lanes on the south and north sides of the lower deck, respectively. B, D, N and Q subway routes use this bridge.
Views of the Manhattan Bridge, including upper and lower levels: