I noticed that many railroad bridges as well as older PA highway overpasses have a only two main girders that are built to the side of the overhead structure while the deck is supported on small beams that cross between the two main girders and smaller parallel beams. Also this one that carries CR 537 over US 30 in Camden, NJ has the same principal.
https://www.google.com/maps/place/Camden,+NJ/@39.9437111,-75.1067749,3a,75y,323.44h,79.68t/data=!3m4!1e1!3m2!1s31etEQdEtthPaGOkxQS0BA!2e0!4m2!3m1!1s0x89c6c9192e360043:0xdfe36b76a1938686
You can see how the bridge only has two large girders to support the load instead of a whole bunch of long thick girders to support the upper road like usual. I am curious to know the name of this type of structure.
That is called a Thru Girder bridge.
What about this type, with vertical members that are integral with the spans? And that often aren't vertical? They're nonexistent in my own state, but quite common in Tennessee:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FgDWN2kO.jpg&hash=9182054e9ae872d81789e704abc839218d2d73e9)
And, while I'm asking ignorant bridge questions, what about this type?
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FiMvD3Cw.jpg%3F1&hash=cb17383d09c296e31581cf4320ee1a96aaf04402)
Steel deck girder and looks like a reinforced concrete deck girder, but could be different without an underneath shot of the bridge.
The unusual piers don't change that.