The spillway elevation was raised from 187' to 300' in 1963. Prior to this time there was a crossing of the upper lake at the bottom of section 22, so a possible earlier location for this bridge. The earlier, lower level lake did not have a road across the spillway.
I agree Luke, I don't see anything to suggest the endposts extend down to create truss legs.
Doubtful, as a bedstead has legs that function as support/substructure, and this appears to be more of a case of vertical endposts.
I feel like this could technically be reclassified as a bedstead Pennsylvania through truss - perhaps the only on on the site - because the end posts do act like those of a traditional bedstead in this relocated single-span scenario.
Because of the vertical end posts, this bridge appears to me to have been one span of a multi span bridge when first installed at the original unknown location.
Yeah I've done a bit more research & a second site visit and you're right about the legs not being bedsteads. Sorry, premature conclusion. I thought maybe they extended down into the concrete abutments, since many bedsteads have their legs encased in concrete, but that's clearly not the case.