The bridge, as well as other objectives and large pieces of terrain, will be considered "part of the table" and cannot be removed or destroyed.
For better or for worse... 
Whaaaa? I can understand the bridge, but c'mon -- it's part of the fun if objectives, hills, forrests get sucked into the warp by vortex grenades 
Basically, anything that's not a permanent part of the table should be free game to destroy, given the right equipment ;P
c'mon Chase!
I understand what you mean, but when you see the size of some of the pieces of terrain / objectives you’ll understand why we consider them "part of the table." It would take 20 min to remove some of them when you consider the models on or around them.
Most buildings, forests, and smaller terrain features will be removed by the grenades.
The tables are really coming together and by the end of the night tonight they should look really badass. I'm very excited to witness the carnage.
