I'm asking because I've been in standstil traffic (in my car) on the Lisbon "golden gate" type bridge and that thing was freaking bouncing up and down from traffic on other lanes.
Interestingly, the 25 of April Bridge in Lisbon was made by the American Bridge Company, same as the Bay Bridge, but not the Golden Gate.
And yes, it's normal. That bridge is very well maintained (there's a whole team there working daily, afaik, and I've witnessed many interventions in the past).
Now that you mention it, the diagonal braces on the piers (no idea how they're actually called) look very similar to the Bay Bridge. But to the casual observer, the number of piers and the color look more like the Golden Gate bridge, plus that's by far the better known one, so I'm not surprised it got this nickname...
Trains cross bridges easily as they're either balanced with each half on each side, or half on and half on ground. And other time's just between these stable points. Furthermore, trains run on tracks which reduces chance of turning acceleration.
Railways work well in the center of bridges. One bridge that violates this principle is the Manhattan Bridge; it was built before we had fancy engineering simulations or much experience with railway suspension bridges at all, and so the lower deck is a pair of railway tracks on either side of a roadway.
This unusual design is very stressful on the bridge and has resulted in expensive rehabilitation programs.
The thing about floating bridges is they don't need to span a waterway. The just need to link the part where getting onto the bridge then the bridge itself move to the exit section.
Floating bridges also don't necessarily need to have fixed points to load and unload. With suitable stabilisation and propulsion, they should be able to move to any number of loading and unloading points. We could have a floating bridge per train, vehicle, or any unit or set of users.
there will be a rail link across a floating bridge in seattle opening in 2025.
it was supposed to open earlier, but the contractor messed up the concrete pour and is fixing it at their own cost. but that doesn't have much to do with the fundamentals of the floating bridge itself.
But it's true that big structures are often designed to move as a way to deal with forces. It's much better than something firm that doesn't move until it snaps.
I'm asking because I've been in standstil traffic (in my car) on the Lisbon "golden gate" type bridge and that thing was freaking bouncing up and down from traffic on other lanes.