Look for the part where Godzilla is walking across the Brooklyn Bridge. Godzilla breaks all the cables on the bridge as she walks on it. The Brooklyn Bridge is a suspension bridge, which means the cables are what hold it up. If the cables broke, the bridge would fall down.
Well, the bridge does start to fall down, that is why the cab nearly doesn't make it. It is not going to collapse instantly as it is supported by the central pillars as well.
I'm not a bridge expert, but doesn't the bridge have to be planted on the ground somewhere. and the suspension cables attach TO the BRIDGE. Earthlings have something called "gravity" so either the bridge is levitating or you are wrong