"The size of a bridge" is an odd metric, since bridges are pretty much linear. "The length of the Golden Gate Bridge" would have given me a somewhat better idea of the threat. Otherwise, I'm just visualizing a long, spindly thing that would break up in the atmosphere.

I mean, all of this is kinda moot, since it's not going to hit Earth. And even if it were I don't really know how destructive this would be, beyond knowing that "over a thousand feet long" sounds pretty bad. And it's not like I have a good suggested alternative for comparing volumes of things -- though maybe mass might be a better unit than volume or area.