Pittsburgh has many bridges, not just these big spans on the big rivers, but small ones, too, that you don’t even realize you’re crossing. This particular span is the West End Bridge, called a “bowstring arch bridge”, one of several crossing the three rivers in Pittsburgh.
If I think too long about crossing a bridge as I’m crossing I’ll start to feel a little panic, especially after seeing the bridge in Minneapolis simply ripple and collapse. After learning about bridges, though, I am comforted by the fact that the slight downward pressure caused by the miniscule weight of my 1995 Ford Escort helps to pull the vertical cords taught taking the pressure with it, pulling the upper arch slightly downward and sending the pressure out the ends toward the earth on either side of the bridge.
If that just confuses you, don’t worry, just remember that you’re relatively safe when crossing the river on one of these bridges.