James,in picture #1 I noticed a N/S and a CSX engine behind the BNSF engine.It's weird to me but there probably is an explanation for 3 different engines hauling freight.
when was this bridge built?
The 1903/13 15' quad shows a single track. In 1945 there is a double track. Probably the original single track used the stone piers, the second track went on the concrete extensions, then the original track was scrapped at some time later than 1945. The 1954 7.5' shows the double track ending at Times Beach just before the bridge and a single track continuing toward St. Louis.
To me, it appears that the existing bridge was added onto an older deck truss that used the double track piers. The old deck truss probably was 30 years or so older than the current truss, and was probably removed when the double track was no longer necessary.
I was just getting ready to ask why this bridge was not double-tracked at the outset. I mean, the builders built the piers for a double-track bridge.
This is the old Frisco, and now BNSF Cuba Sub.
what rr is this on?
This bridge was built with extra wide piers for a possible second track.
Looks like the current trusses were probably built in 1923, judging by the stamp on the abutment in picture #10. In addition, the nearby Valley Park bridge was also built at the same time as part of a double tracking project:
http://bridgehunter.com/mo/st-louis/valley-park-rr/