Right on the money with the cantilever diagnosis and diagram of compression and tension members.
You can confirm it in the photo—the chords along the bottom and the ones angled upwards from the piers are box girders with oval holes—a compression member. The ones angled down from the top of the piers are I beams—tension members.
It’s curious that people call it an “arch” or a “deck truss” when it’s so clearly a cantilever—a truss would have tension members along the bottom, and would be tallest midspan, not around the piers. And arch would need a beefier arch for such a massive bridge. (Like the 494 bridge over the Mississippi or the Cedar Ave Bridges over the Minnesota River elsewhere in town—these are 3 or 4 lane bridges and have much fatter tubular steel arch members.) I can see most people getting it wrong, but surely there must be a few people that the media has found that actually understand bridges. (But, when they keep saying cars fell 64 feet to the river and any dummy can tell it’s more like 100’, I guess I’m overoptimistic)
Note also the views from MS Earth, the on-shore cantilever arms are one segment longer than the arms making the central span. So unlike classic cantilevers that have anchored on-shore ends as a counterweight to a suspended truss in the middle, this cantilever has extended on-shore arms, which probably function as something of a “suspended truss” on shore.
Jeffers—the diagrams from p. 49 and 50 of the MnDOT report—can you tell if the “reversal members” are on the center span or the on-shore arms? I’m guessing the on-shore arms.
On that same note, has anyone found a diagram in the MnDOT report that identifies where all the locations (pier 6, L4, etc.) are on the bridge itself?
There are reversal members on all three truss spans.
Regarding shore-end cantilever counterweights, see my most recrent post above regarding “crossbeams”. In effect, the riverward ends of approach spans functioned as counterweights.